[K12OSN] SATA vs SCSI
Chris Kacoroski
ckacoroski at nsd.org
Mon Sep 20 18:10:29 UTC 2004
Liam,
I did several tests with SATA and SCSI and found out that the controller
card is a limiting factor. The fundamental difference between the two
technologies is that SCSI drives queue up the requests and the optimize
the path of the r/w head across the disk. SATA do not have this ability
so the r/w head wanders all over the disk handling the requests in a
first come, first serve basis.
What this means, is that if you are reading or writing one large file,
SATA perform as good as SCSI (if they have the same spindle speed). If
you have several different processes r/w to multiple files on disk, SCSI
out performs SATA by a large margin. The new SATA standard out sometime
next year is suppose to include queueing, but until then SCSI is
definitely worth it for small installations like yours.
If you have a large installation (e.g. 2TB+ of disk), you can use a
device like the EonStor raid which connects SATA disks to a scsi
controller and performs very well. I have one of these and plan to get
another one for a different application. I tried 3ware cards, but they
failed in my application (I still use them to mirror the system disks
and they work great for that).
cheers,
ski
Liam Marshall wrote:
> this is my current hard drive situation, which will probably have to
> stay until next year.
>
> 1 - small regular ide drive for the system to boot off of. I
> t holds the /boot partition and does nothing else
> 1 - 8 GB ibm SCSI drive, holding /root /usr etc
> 1 - 18 HB Seagate SCSI holding /home /opt and the /swap partition
>
> no raid
>
> In an earlier thread, someone mentioned using SATA drives successfully
> with a large number of users, 25+
> When I go to configure next years server(we will upgrade) can I use SATA
> drives in a raid 0 configuration? I want to increase performance hence
> the raid 0, but heard that SATA drives might not handle a class of 25+
> workstations
>
> any advice?
>
> SATA is cheaper, I assume, than SCSI, so that would be a preferred path
> if true
>
>
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--
"When we try to pick out anything by itself, we find it
connected to the entire universe" John Muir
Chris "Ski" Kacoroski, ckacoroski at nsd.org, 425-489-6263
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