Ok to leave slave HD cable connected with power off?

Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

I want to use a slave hard drive occasionally as a Drive Image backup disk.
I don't like the idea of the backup hard drive always being powered on
because hard drives are rated for a certain number of on/off cycles. Can I
just unplug the power cable and leave the flat ribbon cable connected when I
don't need to use the backup drive or will that create some reliability
issues with my master hard drive on the end of the cable?
44 answers Last reply
More about leave slave cable connected power
  1. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "Mark" wrote:
    > I want to use a slave hard drive occasionally as a Drive Image
    > backup disk. I don't like the idea of the backup hard drive
    > always being powered on because hard drives are rated for
    > a certain number of on/off cycles. Can I just unplug the power
    > cable and leave the flat ribbon cable connected when I don't
    > need to use the backup drive or will that create some reliability
    > issues with my master hard drive on the end of the cable?


    This has been discussed several times in the past year, and
    although there are the usual specification freaks, no one had
    any verifiable reason or data to indicate that having a "dead"
    HD at the intermediate position of an IDE cable would hurt
    the data in any way. I can't think of an obvious reason not
    to have the "dead" HD at the *end* of the cable, either, since
    I can't see why the "dead" circuitry (i.e. unpowered circuitry)
    at the end of the cable would cause less or more signal
    reflections than "live" circuitry.

    The question does arise, though, why you can't unplug
    the intermediate connector from the HD as well as the
    power connector? Are you planning on controling the
    HD power with a switch? If so, make that switch hard
    to reach! :-)

    *TimDaniels*
  2. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    A neater solution would be a removeable HDD caddy - about £15 - fits into 5
    1/4" bay and the HDD caddy slides in and out. You can't hot-swap ofcourse,
    but when you wanted to access the drive you've only got to slide it in
    before booting.
    Will not cause any probs for your bootdrive.
    "Mark" <news1@IntelligentSoftwareSystems.com> wrote in message
    news:10dsl0j4i6q6n2c@corp.supernews.com...
    > I want to use a slave hard drive occasionally as a Drive Image backup
    disk.
    > I don't like the idea of the backup hard drive always being powered on
    > because hard drives are rated for a certain number of on/off cycles. Can
    I
    > just unplug the power cable and leave the flat ribbon cable connected when
    I
    > don't need to use the backup drive or will that create some reliability
    > issues with my master hard drive on the end of the cable?
    >
    >
  3. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    Timothy Daniels wrote:

    > "Mark" wrote:
    >
    >>I want to use a slave hard drive occasionally as a Drive Image
    >>backup disk. I don't like the idea of the backup hard drive
    >>always being powered on because hard drives are rated for
    >>a certain number of on/off cycles. Can I just unplug the power
    >>cable and leave the flat ribbon cable connected when I don't
    >>need to use the backup drive or will that create some reliability
    >>issues with my master hard drive on the end of the cable?
    >
    >
    >
    > This has been discussed several times in the past year, and
    > although there are the usual specification freaks, no one had
    > any verifiable reason or data to indicate that having a "dead"
    > HD at the intermediate position of an IDE cable would hurt
    > the data in any way. I can't think of an obvious reason not
    > to have the "dead" HD at the *end* of the cable, either, since
    > I can't see why the "dead" circuitry (i.e. unpowered circuitry)
    > at the end of the cable would cause less or more signal
    > reflections than "live" circuitry.
    >

    What about potential harm to the unpowered drive's interface
    circuits?

    > The question does arise, though, why you can't unplug
    > the intermediate connector from the HD as well as the
    > power connector? Are you planning on controling the
    > HD power with a switch? If so, make that switch hard
    > to reach! :-)
    >
    > *TimDaniels*


    --
    The e-mail address in our reply-to line is reversed in an attempt to
    minimize spam. Our true address is of the form che...@prodigy.net.
  4. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "GTS" <gts123NOSPAM@ntlworld.com> wrote in message
    news:cGDDc.469$m32.2@newsfe6-win...
    > A neater solution would be a removeable HDD caddy - about £15 - fits into
    5
    > 1/4" bay and the HDD caddy slides in and out. You can't hot-swap ofcourse,
    > but when you wanted to access the drive you've only got to slide it in
    > before booting.

    Before power-on actually.

    > Will not cause any probs for your bootdrive.
    > "Mark" <news1@IntelligentSoftwareSystems.com> wrote in message
    > news:10dsl0j4i6q6n2c@corp.supernews.com...
    > > I want to use a slave hard drive occasionally as a Drive Image backup
    > disk.
    > > I don't like the idea of the backup hard drive always being powered on
    > > because hard drives are rated for a certain number of on/off cycles.
    Can
    > I
    > > just unplug the power cable and leave the flat ribbon cable connected
    when
    > I
    > > don't need to use the backup drive or will that create some reliability
    > > issues with my master hard drive on the end of the cable?
    > >
    > >
    >
    >
  5. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "Timothy Daniels" <TDaniels@NoSpamDot.com> wrote in message
    news:c8ydnShARJWHnELdRVn-sQ@comcast.com...
    > "Mark" wrote:
    > > I want to use a slave hard drive occasionally as a Drive Image
    > > backup disk. I don't like the idea of the backup hard drive
    > > always being powered on because hard drives are rated for
    > > a certain number of on/off cycles. Can I just unplug the power
    > > cable and leave the flat ribbon cable connected when I don't
    > > need to use the backup drive or will that create some reliability
    > > issues with my master hard drive on the end of the cable?
    >
    >
    > This has been discussed several times in the past year, and
    > although there are the usual specification freaks, no one had
    > any verifiable reason or data to indicate that having a "dead"
    > HD at the intermediate position of an IDE cable would hurt
    > the data in any way.

    Of course it will not proactively do anything since it's powered-off.

    > I can't think of an obvious reason not
    > to have the "dead" HD at the *end* of the cable, either, since
    > I can't see why the "dead" circuitry (i.e. unpowered circuitry)
    > at the end of the cable would cause less or more signal
    > reflections than "live" circuitry.

    Middle of the cable, as what's being discussed is a slave drive. The
    question is will unpowered circuitry behave well on an active/powered cable.
    Will it load something or draw current...I don't know.
  6. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "CJT" <abujlehc@prodigy.net> wrote in message
    news:40DF17C3.8060904@prodigy.net...
    > Timothy Daniels wrote:
    >
    > > "Mark" wrote:
    > >
    > >>I want to use a slave hard drive occasionally as a Drive Image
    > >>backup disk. I don't like the idea of the backup hard drive
    > >>always being powered on because hard drives are rated for
    > >>a certain number of on/off cycles. Can I just unplug the power
    > >>cable and leave the flat ribbon cable connected when I don't
    > >>need to use the backup drive or will that create some reliability
    > >>issues with my master hard drive on the end of the cable?
    > >
    > >
    > >
    > > This has been discussed several times in the past year, and
    > > although there are the usual specification freaks, no one had
    > > any verifiable reason or data to indicate that having a "dead"
    > > HD at the intermediate position of an IDE cable would hurt
    > > the data in any way. I can't think of an obvious reason not
    > > to have the "dead" HD at the *end* of the cable, either, since
    > > I can't see why the "dead" circuitry (i.e. unpowered circuitry)
    > > at the end of the cable would cause less or more signal
    > > reflections than "live" circuitry.
    > >
    >
    > What about potential harm to the unpowered drive's interface
    > circuits?

    That's the question!
  7. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "Ron Reaugh" wrote:
    > "Timothy Daniels" wrote:
    > > "Mark" wrote:
    > > > I want to use a slave hard drive occasionally as a Drive Image
    > > > backup disk. I don't like the idea of the backup hard drive
    > > > always being powered on because hard drives are rated for
    > > > a certain number of on/off cycles. Can I just unplug the power
    > > > cable and leave the flat ribbon cable connected when I don't
    > > > need to use the backup drive or will that create some reliability
    > > > issues with my master hard drive on the end of the cable?
    > >
    > >
    > > This has been discussed several times in the past year, and
    > > although there are the usual specification freaks, no one had
    > > any verifiable reason or data to indicate that having a "dead"
    > > HD at the intermediate position of an IDE cable would hurt
    > > the data in any way.
    >
    > Of course it will not proactively do anything since it's powered-off.
    >
    > > I can't think of an obvious reason not
    > > to have the "dead" HD at the *end* of the cable, either, since
    > > I can't see why the "dead" circuitry (i.e. unpowered circuitry)
    > > at the end of the cable would cause less or more signal
    > > reflections than "live" circuitry.
    >
    > Middle of the cable, as what's being discussed is a slave drive. The
    > question is will unpowered circuitry behave well on an active/powered cable.
    > Will it load something or draw current...I don't know.


    The question is whether data on its way to the end connector would
    be absorbed or reflected in some way by the dead circuitry at the
    intermediate position. I've tried it. The answer is that the data on
    its way to the end connector is not corrupted.

    *TimDaniels*
  8. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "CJT" asked:
    > Timothy Daniels wrote:
    >
    > > "Mark" wrote:
    > >
    > >>I want to use a slave hard drive occasionally as a Drive Image
    > >>backup disk. I don't like the idea of the backup hard drive
    > >>always being powered on because hard drives are rated for
    > >>a certain number of on/off cycles. Can I just unplug the power
    > >>cable and leave the flat ribbon cable connected when I don't
    > >>need to use the backup drive or will that create some reliability
    > >>issues with my master hard drive on the end of the cable?
    > >
    > >
    > >
    > > This has been discussed several times in the past year, and
    > > although there are the usual specification freaks, no one had
    > > any verifiable reason or data to indicate that having a "dead"
    > > HD at the intermediate position of an IDE cable would hurt
    > > the data in any way. I can't think of an obvious reason not
    > > to have the "dead" HD at the *end* of the cable, either, since
    > > I can't see why the "dead" circuitry (i.e. unpowered circuitry)
    > > at the end of the cable would cause less or more signal
    > > reflections than "live" circuitry.
    > >
    >
    > What about potential harm to the unpowered drive's interface
    > circuits?


    Why should they be harmed when unpowered and not harmed
    when powered?

    *TimDaniels*
  9. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "Ron Reaugh" wrote:
    >
    > "CJT" wrote:
    > > Timothy Daniels wrote:
    > >
    > > > "Mark" wrote:
    > > >
    > > >>I want to use a slave hard drive occasionally as a Drive Image
    > > >>backup disk. I don't like the idea of the backup hard drive
    > > >>always being powered on because hard drives are rated for
    > > >>a certain number of on/off cycles. Can I just unplug the power
    > > >>cable and leave the flat ribbon cable connected when I don't
    > > >>need to use the backup drive or will that create some reliability
    > > >>issues with my master hard drive on the end of the cable?
    > > >
    > > >
    > > >
    > > > This has been discussed several times in the past year, and
    > > > although there are the usual specification freaks, no one had
    > > > any verifiable reason or data to indicate that having a "dead"
    > > > HD at the intermediate position of an IDE cable would hurt
    > > > the data in any way. I can't think of an obvious reason not
    > > > to have the "dead" HD at the *end* of the cable, either, since
    > > > I can't see why the "dead" circuitry (i.e. unpowered circuitry)
    > > > at the end of the cable would cause less or more signal
    > > > reflections than "live" circuitry.
    > > >
    > >
    > > What about potential harm to the unpowered drive's interface
    > > circuits?
    >
    > That's the question!


    Here's the answer: There's no harm. I've tried it.

    *TimDaniels*
  10. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    Timothy Daniels wrote:

    > "CJT" asked:
    >
    >>Timothy Daniels wrote:
    >>
    >>
    >>>"Mark" wrote:
    >>>
    >>>
    >>>>I want to use a slave hard drive occasionally as a Drive Image
    >>>>backup disk. I don't like the idea of the backup hard drive
    >>>>always being powered on because hard drives are rated for
    >>>>a certain number of on/off cycles. Can I just unplug the power
    >>>>cable and leave the flat ribbon cable connected when I don't
    >>>>need to use the backup drive or will that create some reliability
    >>>>issues with my master hard drive on the end of the cable?
    >>>
    >>>
    >>>
    >>> This has been discussed several times in the past year, and
    >>>although there are the usual specification freaks, no one had
    >>>any verifiable reason or data to indicate that having a "dead"
    >>>HD at the intermediate position of an IDE cable would hurt
    >>>the data in any way. I can't think of an obvious reason not
    >>>to have the "dead" HD at the *end* of the cable, either, since
    >>>I can't see why the "dead" circuitry (i.e. unpowered circuitry)
    >>>at the end of the cable would cause less or more signal
    >>>reflections than "live" circuitry.
    >>>
    >>
    >>What about potential harm to the unpowered drive's interface
    >>circuits?
    >
    >
    >
    > Why should they be harmed when unpowered and not harmed
    > when powered?
    >
    > *TimDaniels*

    Who knows what state they're in when they're unpowered?

    --
    The e-mail address in our reply-to line is reversed in an attempt to
    minimize spam. Our true address is of the form che...@prodigy.net.
  11. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    Timothy Daniels wrote:

    > "Ron Reaugh" wrote:
    >
    >>"CJT" wrote:
    >>
    >>>Timothy Daniels wrote:
    >>>
    >>>
    >>>>"Mark" wrote:
    >>>>
    >>>>
    >>>>>I want to use a slave hard drive occasionally as a Drive Image
    >>>>>backup disk. I don't like the idea of the backup hard drive
    >>>>>always being powered on because hard drives are rated for
    >>>>>a certain number of on/off cycles. Can I just unplug the power
    >>>>>cable and leave the flat ribbon cable connected when I don't
    >>>>>need to use the backup drive or will that create some reliability
    >>>>>issues with my master hard drive on the end of the cable?
    >>>>
    >>>>
    >>>>
    >>>> This has been discussed several times in the past year, and
    >>>>although there are the usual specification freaks, no one had
    >>>>any verifiable reason or data to indicate that having a "dead"
    >>>>HD at the intermediate position of an IDE cable would hurt
    >>>>the data in any way. I can't think of an obvious reason not
    >>>>to have the "dead" HD at the *end* of the cable, either, since
    >>>>I can't see why the "dead" circuitry (i.e. unpowered circuitry)
    >>>>at the end of the cable would cause less or more signal
    >>>>reflections than "live" circuitry.
    >>>>
    >>>
    >>>What about potential harm to the unpowered drive's interface
    >>>circuits?
    >>
    >>That's the question!
    >
    >
    >
    > Here's the answer: There's no harm. I've tried it.
    >
    > *TimDaniels*

    Does the standard contain language requiring that they be designed to
    not be harmed that way? Anecdotal evidence is just that -- it doesn't
    necessarily carry over to drives on which it was not observed.

    --
    The e-mail address in our reply-to line is reversed in an attempt to
    minimize spam. Our true address is of the form che...@prodigy.net.
  12. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "CJT" wrote:
    > Does the standard contain language requiring that they
    > be designed to not be harmed that way? Anecdotal
    > evidence is just that -- it doesn't necessarily carry over
    > to drives on which it was not observed.


    The "standards" don't say anything about that situation
    that I know of. Of more importance to me is that it's
    a "don't care" for my hard drives (Maxtor DiamondMax
    Plus 9s). You are free to care and to fear as much as
    you desire. For others, it's an easy experiment.

    *TimDaniels*
  13. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "CJT" wrote:
    > Who knows what state they're in when they're unpowered?


    1) Is there a "state" when the circuits are unpowered?
    2) How is the "state" of an unpowered circuit going to
    affect the signal passing by?
    3) Why don't you try it and see?

    *TimDaniels*
  14. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "Timothy Daniels" <TDaniels@NoSpamDot.com> wrote in message
    news:c8ydnShARJWHnELdRVn-sQ@comcast.com...
    > "Mark" wrote:
    > > I want to use a slave hard drive occasionally as a Drive Image
    > > backup disk. I don't like the idea of the backup hard drive
    > > always being powered on because hard drives are rated for
    > > a certain number of on/off cycles. Can I just unplug the power
    > > cable and leave the flat ribbon cable connected when I don't
    > > need to use the backup drive or will that create some reliability
    > > issues with my master hard drive on the end of the cable?
    >
    >
    > This has been discussed several times in the past year, and
    > although there are the usual specification freaks, no one had
    > any verifiable reason or data to indicate that having a "dead"
    > HD at the intermediate position of an IDE cable would hurt
    > the data in any way. I can't think of an obvious reason not
    > to have the "dead" HD at the *end* of the cable, either, since
    > I can't see why the "dead" circuitry (i.e. unpowered circuitry)
    > at the end of the cable would cause less or more signal
    > reflections than "live" circuitry.
    >
    > The question does arise, though, why you can't unplug
    > the intermediate connector from the HD as well as the
    > power connector? Are you planning on controling the
    > HD power with a switch? If so, make that switch hard
    > to reach! :-)
    No switch. I just don't want to wear out the connector/pins.

    >
    > *TimDaniels*
  15. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "GTS" <gts123NOSPAM@ntlworld.com> wrote in message
    news:cGDDc.469$m32.2@newsfe6-win...
    > A neater solution would be a removeable HDD caddy - about £15 - fits into
    5
    > 1/4" bay and the HDD caddy slides in and out. You can't hot-swap ofcourse,
    > but when you wanted to access the drive you've only got to slide it in
    > before booting.
    > Will not cause any probs for your bootdrive.
    I have a StarTech removable drive caddy (DRW115ATA) already on the end of
    the cable. After reading prior discussions on this group, I would be
    worried about signal reflections caused by a removable caddy in the middle
    of the cable and making the total cable length too long.

    > "Mark" <news1@IntelligentSoftwareSystems.com> wrote in message
    > news:10dsl0j4i6q6n2c@corp.supernews.com...
    > > I want to use a slave hard drive occasionally as a Drive Image backup
    > disk.
    > > I don't like the idea of the backup hard drive always being powered on
    > > because hard drives are rated for a certain number of on/off cycles.
    Can
    > I
    > > just unplug the power cable and leave the flat ribbon cable connected
    when
    > I
    > > don't need to use the backup drive or will that create some reliability
    > > issues with my master hard drive on the end of the cable?
    > >
    > >
    >
    >
  16. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    Timothy Daniels wrote:

    > "CJT" wrote:
    >
    >>Who knows what state they're in when they're unpowered?
    >
    >
    >
    > 1) Is there a "state" when the circuits are unpowered?

    Of course.

    > 2) How is the "state" of an unpowered circuit going to
    > affect the signal passing by?

    Who knows unless it's specified by the designer?

    > 3) Why don't you try it and see?

    Because it's an engineering question. Would you just build a
    bridge and see if it stays up? If it stays up the first time
    a car goes over it, is that good enough?

    >
    > *TimDaniels*


    --
    The e-mail address in our reply-to line is reversed in an attempt to
    minimize spam. Our true address is of the form che...@prodigy.net.
  17. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "CJT" wrote:
    > Timothy Daniels wrote:
    >
    > > "CJT" wrote:
    > >
    > >>Who knows what state they're in when they're unpowered?
    > >
    > >
    > >
    > > 1) Is there a "state" when the circuits are unpowered?
    >
    > Of course.
    >
    > > 2) How is the "state" of an unpowered circuit going to
    > > affect the signal passing by?
    >
    > Who knows unless it's specified by the designer?
    >
    > > 3) Why don't you try it and see?
    >
    > Because it's an engineering question. Would you just build a
    > bridge and see if it stays up? If it stays up the first time
    > a car goes over it, is that good enough?


    Relax and live life, CJT. Not everything is specified.

    *TimDaniels*
  18. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "Mark" <news1@IntelligentSoftwareSystems.com> wrote in message
    news:10e0lhk8g88558f@corp.supernews.com...
    > "GTS" <gts123NOSPAM@ntlworld.com> wrote in message
    > news:cGDDc.469$m32.2@newsfe6-win...
    > > A neater solution would be a removeable HDD caddy - about £15 - fits
    into
    > 5
    > > 1/4" bay and the HDD caddy slides in and out. You can't hot-swap
    ofcourse,
    > > but when you wanted to access the drive you've only got to slide it in
    > > before booting.
    > > Will not cause any probs for your bootdrive.
    > I have a StarTech removable drive caddy (DRW115ATA) already on the end of
    > the cable. After reading prior discussions on this group, I would be
    > worried about signal reflections caused by a removable caddy in the middle
    > of the cable and making the total cable length too long.

    The reflection issue appears more severly when there's nothing powered at
    the end of the cable. The middle of the cable is much less important. The
    design must include keeping the overall cable length in check.

    > > "Mark" <news1@IntelligentSoftwareSystems.com> wrote in message
    > > news:10dsl0j4i6q6n2c@corp.supernews.com...
    > > > I want to use a slave hard drive occasionally as a Drive Image backup
    > > disk.
    > > > I don't like the idea of the backup hard drive always being powered on
    > > > because hard drives are rated for a certain number of on/off cycles.
    > Can
    > > I
    > > > just unplug the power cable and leave the flat ribbon cable connected
    > when
    > > I
    > > > don't need to use the backup drive or will that create some
    reliability
    > > > issues with my master hard drive on the end of the cable?
    > > >
    > > >
    > >
    > >
    >
    >
  19. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "Ron Reaugh" wrote:
    > The reflection issue appears more severly when there's
    > nothing powered at the end of the cable.

    You are correct in that there should be a device
    connected at the end of the cable to avoid the
    reflections (and the timing of those reflections as
    they reach the intermediate device), but of what
    significance is there in the end device being
    powered or not? Implicit in your statement is
    the assumption that the impedance looking into
    the device from the connector is different
    according to whether it was powered or not.
    Why should the input impedance change with
    power?

    *TimDaniels*
  20. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    Mark wrote:

    > I want to use a slave hard drive occasionally as a Drive Image backup
    > disk. I don't like the idea of the backup hard drive always being powered
    > on
    > because hard drives are rated for a certain number of on/off cycles. Can
    > I just unplug the power cable and leave the flat ribbon cable connected
    > when I don't need to use the backup drive or will that create some
    > reliability issues with my master hard drive on the end of the cable?

    It won't always, but it _can_.

    First DVD burner I ever had was an HP. At one point I had it installed in
    the machine and had forgotten to attach the power cable. I ended up with
    corrupted data on every disk in the machine, not only the slave but also
    the ones on the other channel--the isolation there is not as great as one
    might assume, or at least it wasn't with the Intel BX chipset.

    This got me curious, so I reformatted everything and did some tests and
    found out that with the DVD burner plugged into the signal cable but with
    no power I did indeed get data corruption on the other attached drives, but
    with it not plugged into the signal cable or with it connected to both the
    signal and the power cables everything worked fine.

    That's the only time I've ever had that happen or heard of it happening, so
    it's unusual, but it _can_ happen and the only way to know for sure would
    be to test.

    --
    --John
    Reply to jclarke at ae tee tee global dot net
    (was jclarke at eye bee em dot net)
  21. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "Timothy Daniels" <TDaniels@NoSpamDot.com> wrote in message
    news:iYWdndvfn7DfIn3d4p2dnA@comcast.com...
    > "Ron Reaugh" wrote:
    > > The reflection issue appears more severly when there's
    > > nothing powered at the end of the cable.
    >
    > You are correct in that there should be a device
    > connected at the end of the cable to avoid the
    > reflections (and the timing of those reflections as
    > they reach the intermediate device), but of what
    > significance is there in the end device being
    > powered or not?

    Depends on what's there. Unpowered it may not supply what's needed to keep
    the reflections down.

    > Implicit in your statement is
    > the assumption that the impedance looking into
    > the device from the connector is different
    > according to whether it was powered or not.

    Exactly and frequently that is the case and there could also be a bias
    issue.

    > Why should the input impedance change with
    > power?

    Active devices may be involved.
  22. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "Ron Reaugh" wrote:
    >
    > "Timothy Daniels" asked:
    > > but of what
    > > significance is there in the end device being
    > > powered or not?
    >
    > Depends on what's there. Unpowered it may not supply
    > what's needed to keep the reflections down.


    What might that be? That is, what active device might
    there be that would function to suppress reflections from
    itself or what it controlled?

    *TimDaniels*
  23. Archived from groups: comp.sys.ibm.pc.hardware.storage,aus.computers (More info?)

    In article <a4idnRH42_jJ0X3d4p2dnA@comcast.com>,
    "Timothy Daniels" <TDaniels@NoSpamDot.com> wrote:
    >"CJT" wrote:
    >> Who knows what state they're in when they're unpowered?
    >
    > 1) Is there a "state" when the circuits are unpowered?
    > 2) How is the "state" of an unpowered circuit going to
    > affect the signal passing by?

    Going back a few years, ISTR that the manual for the TRS-80 Model I
    stated that peripherals should all be powered up before (or at least
    simultaneously with) the computer to avoid damage to unpowered
    circuits. Don't ask me why this was recommended; but I *assumed* it
    had something to do with signal current paths that were perhaps "open"
    when they shouldn't have been, and thus more susceptible.

    > 3) Why don't you try it and see?


    Cheers, Phred.

    --
    ppnerkDELETE@THISyahoo.com.INVALID
  24. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    Timothy Daniels wrote:

    > "Ron Reaugh" wrote:
    >
    >>"Timothy Daniels" asked:
    >>
    >>> but of what
    >>> significance is there in the end device being
    >>> powered or not?
    >>
    >>Depends on what's there. Unpowered it may not supply
    >>what's needed to keep the reflections down.
    >
    >
    >
    > What might that be? That is, what active device might
    > there be that would function to suppress reflections from
    > itself or what it controlled?
    >
    > *TimDaniels*

    transistors


    --
    The e-mail address in our reply-to line is reversed in an attempt to
    minimize spam. Our true address is of the form che...@prodigy.net.
  25. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "CJT" wrote:
    > Timothy Daniels wrote:
    > > That is, what active device might
    > > there be that would function to suppress reflections from
    > > itself or what it controlled?
    >
    > transistors


    Any idea how transistors would control their input impedance?

    *TimDaniels*
  26. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "Timothy Daniels" <TDaniels@NoSpamDot.com> wrote in message
    news:3JOdnaFBDoiJP3zdRVn-vg@comcast.com...
    > "CJT" wrote:
    > > Timothy Daniels wrote:
    > > > That is, what active device might
    > > > there be that would function to suppress reflections from
    > > > itself or what it controlled?
    > >
    > > transistors
    >
    >
    > Any idea how transistors would control their input impedance?

    Have you ever studied the impedance of a diode. What do you think the input
    of a transistor is and then the possibilities get more complicated from
    there. You're outa your depth.
  27. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "Ron Reaugh" wrote:
    >
    > "Timothy Daniels" wrote:
    > > Any idea how transistors would control their input impedance?
    >
    > Have you ever studied the impedance of a diode. What do you
    > think the input of a transistor is and then the possibilities get more
    > complicated from there. You're outa your depth.


    You're saying the input side of a transistor is a diode?

    *TimDaniels*
  28. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    Timothy Daniels wrote:
    > "CJT" wrote:
    >
    >>Timothy Daniels wrote:
    >>
    >>> That is, what active device might
    >>> there be that would function to suppress reflections from
    >>> itself or what it controlled?
    >>
    >>transistors
    >
    >
    >
    > Any idea how transistors would control their input impedance?
    >
    > *TimDaniels*

    Sure. Ever hear of a virtual ground?


    --
    The e-mail address in our reply-to line is reversed in an attempt to
    minimize spam. Our true address is of the form che...@prodigy.net.
  29. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "CJT" wrote:
    > Timothy Daniels wrote:
    > > Any idea how transistors would control their input impedance?
    >
    > Sure. Ever hear of a virtual ground?


    Is a virtual ground how an IDE device controls signal reflections?

    *TimDaniels*
  30. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    Timothy Daniels wrote:

    > "CJT" wrote:
    >
    >>Timothy Daniels wrote:
    >>
    >>> Any idea how transistors would control their input impedance?
    >>
    >>Sure. Ever hear of a virtual ground?
    >
    >
    >
    > Is a virtual ground how an IDE device controls signal reflections?
    >
    > *TimDaniels*

    Not likely, although I haven't reviewed the input circuitry of every IDE
    device and controller, so I can't rule out that possibility. It was
    presented as one example of how a circuit might change impedance via
    active circuitry, in response to your question (which had drifted away
    from the original discussion, so maybe I shouldn't have bothered).

    This wasn't just about impedance, or even reflections; at issue was
    possible circuit damage to the unpowered drive.

    --
    The e-mail address in our reply-to line is reversed in an attempt to
    minimize spam. Our true address is of the form che...@prodigy.net.
  31. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "CJT" wrote:
    > This wasn't just about impedance, or even reflections;
    > at issue was possible circuit damage to the unpowered drive.


    Right. And circuit damage is even less likely than
    data corruption. And before you dredge up some
    arcane exception, let me restrict the following
    comment to my own Maxtor DiamondMax Plus 9s:
    It worked for me - no circuit damage!! I hooked 'em
    up dead, first at the intermediate position, then at the
    end position, and they both are still working.

    *TimDaniels*
  32. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    Timothy Daniels wrote:

    > "CJT" wrote:
    >
    >>This wasn't just about impedance, or even reflections;
    >>at issue was possible circuit damage to the unpowered drive.
    >
    >
    >
    > Right. And circuit damage is even less likely than
    > data corruption. And before you dredge up some
    > arcane exception, let me restrict the following
    > comment to my own Maxtor DiamondMax Plus 9s:
    > It worked for me - no circuit damage!! I hooked 'em
    > up dead, first at the intermediate position, then at the
    > end position, and they both are still working.
    >
    > *TimDaniels*

    Good for you. I'm going to refrain from that sort of thing,
    except perhaps with a drive that's spec'd for hot plugging.
    Call me overly cautious if you like, but my data is important
    to me.

    --
    The e-mail address in our reply-to line is reversed in an attempt to
    minimize spam. Our true address is of the form che...@prodigy.net.
  33. Archived from groups: comp.sys.ibm.pc.hardware.storage,aus.computers (More info?)

    Phred <ppnerkDELETETHIS@yahoo.com> wrote
    in message news:2kdbfmFugvvU2@uni-berlin.de...
    > Timothy Daniels <TDaniels@NoSpamDot.com> wrote
    >> CJT wrote

    >>> Who knows what state they're in when they're unpowered?

    >> 1) Is there a "state" when the circuits are unpowered?
    >> 2) How is the "state" of an unpowered circuit going to
    >> affect the signal passing by?

    > Going back a few years, ISTR that the manual for the TRS-80 Model
    > I stated that peripherals should all be powered up before (or at least
    > simultaneously with) the computer to avoid damage to unpowered circuits.

    It was always much more complicated than that.

    RS232 was designed right from the start to not only
    handle that fine, but to hand shorts in the cable fine too.

    In spades with USB and firewire now too.

    > Don't ask me why this was recommended; but I *assumed* it
    > had something to do with signal current paths that were perhaps
    > "open" when they shouldn't have been, and thus more susceptible.

    To some extent. Not relevant now tho.

    >> 3) Why don't you try it and see?
  34. Archived from groups: comp.sys.ibm.pc.hardware.storage,aus.computers (More info?)

    In article <2kej0lF18gr2U1@uni-berlin.de>,
    "Rod Speed" <rod_speed@yahoo.com> wrote:
    >
    >Phred <ppnerkDELETETHIS@yahoo.com> wrote
    >in message news:2kdbfmFugvvU2@uni-berlin.de...
    >> Timothy Daniels <TDaniels@NoSpamDot.com> wrote
    >>> CJT wrote
    >>>> Who knows what state they're in when they're unpowered?
    >>> 1) Is there a "state" when the circuits are unpowered?
    >>> 2) How is the "state" of an unpowered circuit going to
    >>> affect the signal passing by?
    >
    >> Going back a few years, ISTR that the manual for the TRS-80 Model
    >> I stated that peripherals should all be powered up before (or at least
    >> simultaneously with) the computer to avoid damage to unpowered circuits.
    >
    >It was always much more complicated than that.

    It always is. :-)

    >RS232 was designed right from the start to not only
    >handle that fine, but to hand shorts in the cable fine too.
    >In spades with USB and firewire now too.
    >
    >> Don't ask me why this was recommended; but I *assumed* it
    >> had something to do with signal current paths that were perhaps
    >> "open" when they shouldn't have been, and thus more susceptible.
    >
    >To some extent. Not relevant now tho.

    Getting back to the OP's original question then, I assume you're happy
    to have a 2nd HDD unpowered but not unplugged? Or, perhaps more to
    the point for convenience, which way would you do it -- disconnect the
    power, or disconnect the interface? Or both?


    Cheers, Phred.

    --
    ppnerkDELETE@THISyahoo.com.INVALID
  35. Archived from groups: comp.sys.ibm.pc.hardware.storage,aus.computers (More info?)

    "Phred" wrote:
    > Getting back to the OP's original question then,
    > I assume you're happy to have a 2nd HDD
    > unpowered but not unplugged? Or, perhaps more to
    > the point for convenience, which way would you do
    > it -- disconnect the power, or disconnect the interface?
    > Or both?


    For convenience, of course, put the power through
    an externally operable switch. Arrange it so you can't
    bump it accidentally and where you'd have to stop and
    think before flipping it - maybe a rocker switch with
    guards on either side of the rocker. Leave the data
    connector permanently in place to avoid it getting loose
    with wear and to avoid putting the signals through
    another interface.

    *TimDaniels*
  36. Archived from groups: comp.sys.ibm.pc.hardware.storage,aus.computers (More info?)

    Phred <ppnerkDELETETHIS@yahoo.com> wrote
    in message news:2kfvk2F1kfedU2@uni-berlin.de...
    > Rod Speed <rod_speed@yahoo.com> wrote
    >> Phred <ppnerkDELETETHIS@yahoo.com> wrote
    >>> Timothy Daniels <TDaniels@NoSpamDot.com> wrote
    > >>> CJT wrote

    >>>>> Who knows what state they're in when they're unpowered?
    >>>> 1) Is there a "state" when the circuits are unpowered?
    >>>> 2) How is the "state" of an unpowered circuit going to
    >>>> affect the signal passing by?

    >>> Going back a few years, ISTR that the manual for the TRS-80 Model
    >>> I stated that peripherals should all be powered up before (or at least
    >>> simultaneously with) the computer to avoid damage to unpowered circuits.

    >> It was always much more complicated than that.

    > It always is. :-)

    You're getting there, grasshopper |-)

    >> RS232 was designed right from the start to not only
    >> handle that fine, but to hand shorts in the cable fine too.
    >> In spades with USB and firewire now too.

    >>> Don't ask me why this was recommended; but I *assumed* it
    >>> had something to do with signal current paths that were perhaps
    >>> "open" when they shouldn't have been, and thus more susceptible.

    >> To some extent. Not relevant now tho.

    > Getting back to the OP's original question then,

    Tad radical.

    > I assume you're happy to have a 2nd HDD unpowered but not unplugged?

    Nope, I dont think THAT is a good idea.

    It usually does work, but not always, you can see some
    problems with the bios working out what drives are present etc.

    Thats a different issue to the damage question tho.

    > Or, perhaps more to the point for convenience,
    > which way would you do it -- disconnect the
    > power, or disconnect the interface? Or both?

    I always disconnect both.

    And I dont like the major kludge that removable drive bays
    involve, I prefer to use a proper formal standard like USB
    or firewire or SATA that defines that behaviour fully.
  37. Archived from groups: comp.sys.ibm.pc.hardware.storage,aus.computers (More info?)

    In article <2kghjiF239vnU1@uni-berlin.de>, "Rod Speed" <rod_speed@yahoo.com> wrote:
    >
    >Phred <ppnerkDELETETHIS@yahoo.com> wrote
    >in message news:2kfvk2F1kfedU2@uni-berlin.de...
    >> Rod Speed <rod_speed@yahoo.com> wrote
    >>> Phred <ppnerkDELETETHIS@yahoo.com> wrote
    >>>> Timothy Daniels <TDaniels@NoSpamDot.com> wrote
    >> >>> CJT wrote
    >
    >>>>>> Who knows what state they're in when they're unpowered?
    >>>>> 1) Is there a "state" when the circuits are unpowered?
    >>>>> 2) How is the "state" of an unpowered circuit going to
    >>>>> affect the signal passing by?
    >
    >>>> Going back a few years, ISTR that the manual for the TRS-80 Model
    >>>> I stated that peripherals should all be powered up before (or at least
    >>>> simultaneously with) the computer to avoid damage to unpowered circuits.
    >
    >>> It was always much more complicated than that.
    >
    >> It always is. :-)
    >
    >You're getting there, grasshopper |-)
    >
    >>> RS232 was designed right from the start to not only
    >>> handle that fine, but to hand shorts in the cable fine too.
    >>> In spades with USB and firewire now too.
    >
    >>>> Don't ask me why this was recommended; but I *assumed* it
    >>>> had something to do with signal current paths that were perhaps
    >>>> "open" when they shouldn't have been, and thus more susceptible.
    >
    >>> To some extent. Not relevant now tho.
    >
    >> Getting back to the OP's original question then,
    >
    >Tad radical.
    >
    >> I assume you're happy to have a 2nd HDD unpowered but not unplugged?
    >
    >Nope, I dont think THAT is a good idea.
    >
    >It usually does work, but not always, you can see some
    >problems with the bios working out what drives are present etc.
    >
    >Thats a different issue to the damage question tho.
    >
    >> Or, perhaps more to the point for convenience,
    >> which way would you do it -- disconnect the
    >> power, or disconnect the interface? Or both?
    >
    >I always disconnect both.
    >
    >And I dont like the major kludge that removable drive bays
    >involve, I prefer to use a proper formal standard like USB
    >or firewire or SATA that defines that behaviour fully.

    And you reckon *I'm* a tad radical! 8-)

    Incidentally, does the SATA spec make such things simpler than the
    older ATA?


    Cheers, Phred.

    --
    ppnerkDELETE@THISyahoo.com.INVALID
  38. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    CJT wrote:
    > Timothy Daniels wrote:
    >
    >> "CJT" wrote:
    >>
    >>> This wasn't just about impedance, or even reflections;
    >>> at issue was possible circuit damage to the unpowered drive.
    >>
    >>
    >>
    >>
    >> Right. And circuit damage is even less likely than
    >> data corruption. And before you dredge up some
    >> arcane exception, let me restrict the following
    >> comment to my own Maxtor DiamondMax Plus 9s:
    >> It worked for me - no circuit damage!! I hooked 'em
    >> up dead, first at the intermediate position, then at the
    >> end position, and they both are still working.
    >>
    >> *TimDaniels*
    >
    >
    > Good for you. I'm going to refrain from that sort of thing,
    > except perhaps with a drive that's spec'd for hot plugging.
    > Call me overly cautious if you like, but my data is important
    > to me.
    >

    Ok, all this talk of reflections on IDE cables has me confused - what should I
    be avoiding to minimise reflections? having a drive attached without power?
    having a single drive in the middle connector of an IDE cable with nothing at
    the end?
  39. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "Alex Hunsley" wrote:
    > Ok, all this talk of reflections on IDE cables has me confused -
    > what should I be avoiding to minimise reflections? having a
    > drive attached without power? having a single drive in the
    > middle connector of an IDE cable with nothing at the end?


    Having an open connector (i.e. infinite and discontinuous
    impedance) at the end of a transmission line (i.e. the data
    cable) produces strong reflections. The open connector
    at a mid-point is not as a drastic change in impedance since
    the transmission line continues on past it. Since any connector
    creates some degree of impedance discontinuity, the fewer
    connectors in the signal path the better - which is an argument
    against slide-in hard drive trays. The question is really how
    far do you think your hardware will let you stray from IDE
    specs before there's a data error problem. If you put a
    removeable HD tray at the end of the cable with another HD
    at the mid-point, the mid-point HD may have error problems
    when the end tray is removed. If the removeable tray has the
    only device on the channel, there probably won't be a problem.
    If the removeable tray is at the mid-point, there probably won't
    be a problem. But "probably" is a function of your hardware.
    Personally, the only situation *I'd* avoid is the one with the
    removeable tray at the end with another device at the mid-
    point.

    *TimDaniels*
  40. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "Alex Hunsley" <lard@tardis.ed.ac.molar.uk> wrote in message
    news:10e887ip9gkaf44@corp.supernews.com...
    > CJT wrote:
    > > Timothy Daniels wrote:
    > >
    > >> "CJT" wrote:
    > >>
    > >>> This wasn't just about impedance, or even reflections;
    > >>> at issue was possible circuit damage to the unpowered drive.
    > >>
    > >>
    > >>
    > >>
    > >> Right. And circuit damage is even less likely than
    > >> data corruption. And before you dredge up some
    > >> arcane exception, let me restrict the following
    > >> comment to my own Maxtor DiamondMax Plus 9s:
    > >> It worked for me - no circuit damage!! I hooked 'em
    > >> up dead, first at the intermediate position, then at the
    > >> end position, and they both are still working.
    > >>
    > >> *TimDaniels*
    > >
    > >
    > > Good for you. I'm going to refrain from that sort of thing,
    > > except perhaps with a drive that's spec'd for hot plugging.
    > > Call me overly cautious if you like, but my data is important
    > > to me.
    > >
    >
    > Ok, all this talk of reflections on IDE cables has me confused - what
    should I
    > be avoiding to minimise reflections? having a drive attached without
    power?
    > having a single drive in the middle connector of an IDE cable with nothing
    at
    > the end?

    A single drive always goes at the far end of the cable(as master).
    >
  41. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "Ron Reaugh" <ron-reaugh@worldnet.att.net> wrote in message news:QOZEc.49337$OB3.35507@bgtnsc05-news.ops.worldnet.att.net
    > "Alex Hunsley" <lard@tardis.ed.ac.molar.uk> wrote in message
    > news:10e887ip9gkaf44@corp.supernews.com...
    > > CJT wrote:
    > > > Timothy Daniels wrote:
    > > >
    > > > > "CJT" wrote:
    > > > >
    > > > > > This wasn't just about impedance, or even reflections;
    > > > > > at issue was possible circuit damage to the unpowered drive.
    > > > >
    > > > >
    > > > >
    > > > >
    > > > > Right. And circuit damage is even less likely than
    > > > > data corruption. And before you dredge up some
    > > > > arcane exception, let me restrict the following
    > > > > comment to my own Maxtor DiamondMax Plus 9s:
    > > > > It worked for me - no circuit damage!! I hooked 'em
    > > > > up dead, first at the intermediate position, then at the
    > > > > end position, and they both are still working.
    > > > >
    > > > > *TimDaniels*
    > > >
    > > >
    > > > Good for you. I'm going to refrain from that sort of thing,
    > > > except perhaps with a drive that's spec'd for hot plugging.
    > > > Call me overly cautious if you like, but my data is important
    > > > to me.
    > > >
    > >
    > > Ok, all this talk of reflections on IDE cables has me confused - what should I
    > > be avoiding to minimise reflections? having a drive attached without power?
    > > having a single drive in the middle connector of an IDE cable with nothing at
    > > the end?
    >
    > A single drive always goes at the far end of the cable

    > (as master).

    Nonsense. Can be slave as well.
  42. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "Timothy Daniels" <TDaniels@NoSpamDot.com> wrote in message news:8MmdnTqv6YUv3HndRVn-ug@comcast.com
    > "Alex Hunsley" wrote:
    > > Ok, all this talk of reflections on IDE cables has me confused -
    > > what should I be avoiding to minimise reflections? having a
    > > drive attached without power? having a single drive in the
    > > middle connector of an IDE cable with nothing at the end?
    >
    >
    > Having an open connector (i.e. infinite and discontinuous
    > impedance) at the end of a transmission line (i.e. the data
    > cable) produces strong reflections. The open connector
    > at a mid-point is not as a drastic change in impedance since
    > the transmission line continues on past it. Since any connector
    > creates some degree of impedance discontinuity, the fewer
    > connectors in the signal path the better - which is an argument
    > against slide-in hard drive trays. The question is really how
    > far do you think your hardware will let you stray from IDE
    > specs before there's a data error problem.

    > If you put a
    > removeable HD tray at the end of the cable with another HD
    > at the mid-point, the mid-point HD may have error problems
    > when the end tray is removed.

    So you either do not remove it or replace it with another one.

    > If the removeable tray has the
    > only device on the channel, there probably won't be a problem.

    > If the removeable tray is at the mid-point, there probably won't
    > be a problem.

    A removeable tray at the 'mid-point' is a potential problem when the tray
    is of the kind that uses a small cable between drive and tray connectors.
    That plus maybe an inch (or 2) in tracks and pin lengths on the tray
    connector assemblies will add a substantial stub to the IDE cable (the
    forbidden Y connection) and that may cause reflections by its own.

    > But "probably" is a function of your hardware.
    > Personally, the only situation *I'd* avoid is the one with the
    > removeable tray at the end with another device at the mid-
    > point.
    >
    > *TimDaniels*
  43. Archived from groups: comp.sys.ibm.pc.hardware.storage (More info?)

    "Folkert Rienstra" schreibt:
    >
    > "Timothy Daniels" wrote:
    > > If you put a
    > > removeable HD tray at the end of the cable with another HD
    > > at the mid-point, the mid-point HD may have error problems
    > > when the end tray is removed.
    >
    > So you either do not remove it or replace it with another one.
    >
    > > [.....]
    > > If the removeable tray is at the mid-point, there probably won't
    > > be a problem.
    >
    > A removeable tray at the 'mid-point' is a potential problem when the tray
    > is of the kind that uses a small cable between drive and tray connectors.
    > That plus maybe an inch (or 2) in tracks and pin lengths on the tray
    > connector assemblies will add a substantial stub to the IDE cable (the
    > forbidden Y connection) and that may cause reflections by its own.


    Yup, the stub could be a reflection factory. Whether the timing
    of the reflections over so short a distance would be a problem,
    I have not idea. (That the timing of the reflections may be
    significant may be the reason for the 18"/24" connector
    positioning that is part of the IDE specs.) I guess the answer
    for the removeable tray at the mid-point would be the same as
    the answer for it being at the end - leave a tray with a HD in it
    always plugged in to absorb the signal. But then the question
    again arises about whether the tray (and the HD) must be powered
    in order to absorb signal. If one wanted to limit the wear on a
    removeable HD, the least risky way, IMHO, is to put the tray at
    the end of the cable on a dedicated channel, even if it takes putting
    in a PCI card with an added IDE controller to supply the extra
    channel. Then removal of the tray wouldn't interfere with any
    other device.

    *TimDaniels*
  44. Archived from groups: comp.sys.ibm.pc.hardware.storage,aus.computers (More info?)

    Phred <ppnerkDELETETHIS@yahoo.com> wrote
    in message news:2kilf9F2jnpjU2@uni-berlin.de...
    > Rod Speed <rod_speed@yahoo.com> wrote
    >> Phred <ppnerkDELETETHIS@yahoo.com> wrote
    >>> Rod Speed <rod_speed@yahoo.com> wrote
    >>>> Phred <ppnerkDELETETHIS@yahoo.com> wrote
    >>>>> Timothy Daniels <TDaniels@NoSpamDot.com> wrote
    >>>>>> CJT wrote

    >>>>>>> Who knows what state they're in when they're unpowered?
    >>>>>> 1) Is there a "state" when the circuits are unpowered?
    >>>>>> 2) How is the "state" of an unpowered circuit going to
    >>>>>> affect the signal passing by?

    >>>>> Going back a few years, ISTR that the manual for the TRS-80 Model
    >>>>> I stated that peripherals should all be powered up before (or at least
    >>>>> simultaneously with) the computer to avoid damage to unpowered circuits.

    >>>> It was always much more complicated than that.

    >>> It always is. :-)

    >> You're getting there, grasshopper |-)

    >>>> RS232 was designed right from the start to not only
    >>>> handle that fine, but to hand shorts in the cable fine too.
    >>>> In spades with USB and firewire now too.

    >>>>> Don't ask me why this was recommended; but I *assumed* it
    >>>>> had something to do with signal current paths that were perhaps
    >>>>> "open" when they shouldn't have been, and thus more susceptible.

    >>>> To some extent. Not relevant now tho.

    >>> Getting back to the OP's original question then,

    >> Tad radical.

    >>> I assume you're happy to have a 2nd HDD unpowered but not unplugged?

    >> Nope, I dont think THAT is a good idea.

    >> It usually does work, but not always, you can see some
    >> problems with the bios working out what drives are present etc.

    >> Thats a different issue to the damage question tho.

    >>> Or, perhaps more to the point for convenience,
    >>> which way would you do it -- disconnect the
    >>> power, or disconnect the interface? Or both?

    >> I always disconnect both.

    >> And I dont like the major kludge that removable drive bays
    >> involve, I prefer to use a proper formal standard like USB
    >> or firewire or SATA that defines that behaviour fully.

    > And you reckon *I'm* a tad radical! 8-)

    That aint radical, stupid |-(

    > Incidentally, does the SATA spec make
    > such things simpler than the older ATA?

    Yep, it allows for hot plugging in the formal standard.

    ATA never has.
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