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Need sata I or Sata II info

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September 1, 2007 11:40:22 PM

Still confused about external 2bay hd enclosure.
I have a choice to buy a raid 2xhd enclosure Sil 3512 that is sata 1.5gb/s or another make that uses Sil 3132 sata 3.0gb/s using 2x wd4000kd's in raid 0 .

How much will the hd's slow down using sata 1.5gb/s ?
Supposedly the sata card can do 140MB/s .

Should I even be concerned at slowing the hd's down ?

Thanks for the help.

More about : sata sata info

a b G Storage
September 2, 2007 12:28:07 AM

No difference. Today's hard drives cannot even come close to using all of the bandwith of SATA 1, hell the fastest drives you can buy can barely use 10% of the theoretical bandwidth of SATA 1, let alone SATA 2.
Think about it, 1.5gb per second interface speed, the fastest drives today can only read/write at maybe 120mb per second (in bursts) sustained speed is even much lower.
SATA 2 is purely marketing hype to sell more drives.
September 2, 2007 1:38:56 AM

Thank you.
I thought it was this but was not sure.
Related resources
September 2, 2007 2:06:15 AM

One Gb (gigabit) = 125 MB (megabytes).
SATA 1 (1.5 Gb/sec) = 187.5 MB/sec.
SATA 2 (3.0 Gb/sec) = 375 MB/sec.
September 2, 2007 3:55:07 AM

Thanks so the 2x wd4000kd should get to 100MB/s or upto 140MB/s at most and still be in the safe zone for sataI 1.5Gb/s -> I will get it and test it if slowing them down return it to newegg and get the bit more expensive sata 3.0Gb/s one. Thanks for the help.
a b G Storage
September 2, 2007 4:24:09 AM

Quote:
The computations above are not correct:

SERIAL ATA ("SATA") uses a SERIAL protocol,
which includes one start bit and one stop bit
for every 8 data bits i.e. 10 bits per byte.

Thus, 1.5Gb / 10 bits per byte = 150MB/second

3.0Gb / 10 bits per byte = 300MB/second


> Today's hard drives cannot even come close to using all of the bandwith of SATA 1, hell the fastest drives you can buy can barely use 10% of the theoretical bandwidth of SATA 1, let alone SATA 2.


This latter statement is also not correct:

Western Digital's newest WD10EACS is rated
at 1,156 Mb/second (buffer-to-disk),
which is 77.0% of the bandwidth of the SATA-I
150MB/second interface (not 10%):

http://www.wdc.com/en/products/products.asp?driveid=336&language=en


Sincerely yours,
/s/ Paul Andrew Mitchell
Webmaster, Supreme Law Library
http://www.supremelaw.org/


Whoops, typo on my part. That was meant to be 50% not 10......which in real life is much closer to the actual read/write rates you will get.
a b G Storage
September 2, 2007 4:37:12 PM

Quote:
> SATA 2 is purely marketing hype to sell more drives.

It's NOT "purely marketing hype" [sic].
For that to be true, there would be absolutely
no differences between the two standards,
and that idea is easily disproven.

SATA-2.5 supports a number of features that are
just not available at all in SATA-I HDDs e.g.
Native Command Queuing, Staggered Spin-Up,
and Hot Swap, to name just a few.

There is plenty of documentation already on the
Internet about SATA-II and SATA-2.5.


Humans need to read before they write;
hard drives need to write before they read.


Sincerely yours,
/s/ Paul Andrew Mitchell
Webmaster, Supreme Law Library
http://www.supremelaw.org/


All completely and totally useless, no benefit what so ever to desktop users.

!