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RAID 0 and the formatting of Partitions - Crossposted

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September 20, 2004 5:59:50 PM

Archived from groups: alt.comp.hardware.homebuilt,microsoft.public.win2000.hardware,microsoft.public.windowsxp.general,microsoft.public.windowsxp.hardware (More info?)

Thank you for reading. I know this will seem fussy on my part but I like to
see what I can do here.

I've set up a RAID 0 with a pair of Maxtor SATA drives on an Intel P4 mobo.
It works very well. But some questions came to mind during the setup
process.

I had to establish the striped *before* installing the OS. This involved
going into the bios, selecting the drives for the stipe and interestingly
enough selecting the --size-- of the stripe i.e. one of 32, 64, or 128 kB!
This is before either partitioning or formatting! The process turned two
harddrives into one 'drive'.

So I choose 128 for performance then started the Windows install process.

Through the facilities Windows provides I was able to change the active
partition and get Windows onto something other than a 4KB cluster formated
NTFS partition. Windows got installed on an NTFS partition formatted with
32KB clusters on my 128 KB striped RAID 0 'drive'.

To be honest, I do not have a clue as to what is going on. Does each 32KB
cluster take up 128KB of harddrive space? Should I have arranged for the
NTFS partiton to be formatted with 128KB clusters [ the Disk Management
option however only allows up to 64KB].

How are the 32KB clusters 'split' across the RAID 0 stripe?

Maybe I should have chosen a 64KB RAID 0 stripe then formatted NTFS with
64KB clusters?

BTW because the RAID 0 was set up *before* Windows was installed I didb't
have to upgrade the disks to dynamic.

Any insights welcome - and thanks.

Stephen
Anonymous
a b B Homebuilt system
September 20, 2004 5:59:51 PM

Archived from groups: alt.comp.hardware.homebuilt,microsoft.public.win2000.hardware,microsoft.public.windowsxp.general,microsoft.public.windowsxp.hardware (More info?)

On Mon, 20 Sep 2004 13:59:50 +0000, Stephen wrote:
> Thank you for reading. I know this will seem fussy on my part but I like to
> see what I can do here.
>
> I've set up a RAID 0 with a pair of Maxtor SATA drives on an Intel P4 mobo.
> It works very well. But some questions came to mind during the setup
> process.
>
> I had to establish the striped *before* installing the OS. This involved
> going into the bios, selecting the drives for the stipe and interestingly
> enough selecting the --size-- of the stripe i.e. one of 32, 64, or 128 kB!
> This is before either partitioning or formatting! The process turned two
> harddrives into one 'drive'.
>
> So I choose 128 for performance then started the Windows install process.

Based on what? This means (to me) that you will not see any read
performance improvements for small files, since they will be coming
entirely from one of your disks. Bigger is not necessarily better, in this
case, but it all depends on what you do.

> Through the facilities Windows provides I was able to change the active
> partition and get Windows onto something other than a 4KB cluster formated
> NTFS partition. Windows got installed on an NTFS partition formatted with
> 32KB clusters on my 128 KB striped RAID 0 'drive'.
>
> To be honest, I do not have a clue as to what is going on. Does each 32KB
> cluster take up 128KB of harddrive space? Should I have arranged for the
> NTFS partiton to be formatted with 128KB clusters [ the Disk Management
> option however only allows up to 64KB].

No they are independent.

If you have no clue, then why are you even screwing around with RAID0?
Looking for trouble? You can definitely find it. For example, did you
realize that you just doubled the probability that you will lose all of
your disk files? If one disk fails, you lose it all! Make sure you are
backing up your good stuff regularly. You don't want an "oh, no!" moment.

> How are the 32KB clusters 'split' across the RAID 0 stripe?

They are laid down sequentially. The first 4 32KB clusters are on the 1st
disk (1st 128KB). Then the second 4 32KB clusters are on the 2nd disk.
Then back to the 1st disk (2nd 128KB), etc.

> Maybe I should have chosen a 64KB RAID 0 stripe then formatted NTFS with
> 64KB clusters?

The strips and cluster size are really independent. I don't have enough
experience with NTFS to know whether they benefit from being identical.
Others may tell us. I have not seen any notes to that effect.

Who knows? It really depends on how your system will be used. These are
tuning parameters. The usual way to tune a system is to find some tests
(aka benchmarks) that are similar to your intended operation. Then you can
measure the performance of your setup as you change the parameters and
pick the best combination for you. Note that this is extremely time
consuming. You have to configure with a set of parameters, install
software, run tests, record values. Repeat for every combination of
parameters that you want to consider. Then look at the recorded values and
pick the "best" (different for different people/uses) one (for you).

The other way to go is to Google around and find someone else who has
already done this kind of tuning on their system, verify that they use
their system in a similar way to your usage. Use their parameters.

As an example, a machine that is a news bulletin server (many, many tiny
files) would be tuned differently from one that is an apache web server
serving up large .pdf files. YMMV

> BTW because the RAID 0 was set up *before* Windows was installed I didb't
> have to upgrade the disks to dynamic.

--
Juhan Leemet
Logicognosis, Inc.
September 21, 2004 5:22:36 AM

Archived from groups: alt.comp.hardware.homebuilt,microsoft.public.win2000.hardware,microsoft.public.windowsxp.general,microsoft.public.windowsxp.hardware (More info?)

"Juhan Leemet" <juhan@logicognosis.com> wrote in message
news:p an.2004.09.20.14.48.15.159217@logicognosis.com...
| On Mon, 20 Sep 2004 13:59:50 +0000, Stephen wrote:
| > <clip>
|
| --
| Juhan Leemet
| Logicognosis, Inc.
|

Thanks, yes I do back up my 'data' so I'm not worried *too* much. It's just
that I decided I want to learn about this a bit. I figured the way to do it
is to dive right in and have some fun.

Stephen
Related resources
Anonymous
a b B Homebuilt system
September 21, 2004 6:00:32 AM

Archived from groups: alt.comp.hardware.homebuilt,microsoft.public.win2000.hardware,microsoft.public.windowsxp.general,microsoft.public.windowsxp.hardware (More info?)

"Juhan Leemet" <juhan@logicognosis.com> wrote in message
news:p an.2004.09.20.14.48.15.159217@logicognosis.com...
> On Mon, 20 Sep 2004 13:59:50 +0000, Stephen wrote:
> > Thank you for reading. I know this will seem fussy on my part but I like
to
> > see what I can do here.
> >
> > I've set up a RAID 0 with a pair of Maxtor SATA drives on an Intel P4
mobo.
> > It works very well. But some questions came to mind during the setup
> > process.
> >
> > I had to establish the striped *before* installing the OS. This involved
> > going into the bios, selecting the drives for the stipe and
interestingly
> > enough selecting the --size-- of the stripe i.e. one of 32, 64, or 128
kB!
> > This is before either partitioning or formatting! The process turned two
> > harddrives into one 'drive'.
> >
> > So I choose 128 for performance then started the Windows install
process.
>
> Based on what? This means (to me) that you will not see any read
> performance improvements for small files, since they will be coming
> entirely from one of your disks. Bigger is not necessarily better, in this
> case, but it all depends on what you do.

Yes, I'd have chosen 32K but there is an IF.

The classic definition of stripe size is the element that spans the stripe
set before starting over at the first drive again. If the size he set in
initially is classic and two drives then there is 64K per drive. You have
to read each RAID manual carefully as often they hide that or don't include
that and SOMETIMES even their TS doesn't know. I've been waiting for over 4
years for Promise to answer how they define stripe size. So I'd chose 32K
'stripe units' per drive.
Anonymous
a b B Homebuilt system
September 21, 2004 6:02:55 AM

Archived from groups: alt.comp.hardware.homebuilt,microsoft.public.win2000.hardware,microsoft.public.windowsxp.general,microsoft.public.windowsxp.hardware (More info?)

"Stephen" <replies@newsgroups.thnx> wrote in message
news:qnB3d.97506$Q7D.48337@twister01.bloor.is.net.cable.rogers.com...

> BTW because the RAID 0 was set up *before* Windows was installed I didb't
> have to upgrade the disks to dynamic.

That's expected as the dynamic part arises for the OS's intrinsic SW RAID
functionality and not 3rd party add-on cards.
Anonymous
a b B Homebuilt system
September 25, 2004 1:42:37 AM

Archived from groups: alt.comp.hardware.homebuilt,microsoft.public.win2000.hardware,microsoft.public.windowsxp.general,microsoft.public.windowsxp.hardware (More info?)

On Tue, 21 Sep 2004 01:22:36 +0000, Stephen wrote:
> "Juhan Leemet" <juhan@logicognosis.com> wrote in message
> news:p an.2004.09.20.14.48.15.159217@logicognosis.com...
> | On Mon, 20 Sep 2004 13:59:50 +0000, Stephen wrote:
> | > <clip>
> |
> | --
> | Juhan Leemet
> | Logicognosis, Inc.
> |
>
> Thanks, yes I do back up my 'data' so I'm not worried *too* much. It's just
> that I decided I want to learn about this a bit. I figured the way to do it
> is to dive right in and have some fun.

OK, that is the right attitude. I also like to learn about things by
doing. That is how you really "fix" (as in photographic development) your
"book learning". Didn't mean to be harsh or discouraging. Good luck!

--
Juhan Leemet
Logicognosis, Inc.
!