[CentOS] HA Storage Cookbook?

Ray Van Dolson rayvd at bludgeon.org
Fri Nov 7 22:52:23 UTC 2008


On Fri, Nov 07, 2008 at 05:46:36PM -0500, Joshua Baker-LePain wrote:
> On Fri, 7 Nov 2008 at 2:35pm, nate wrote
>
>> Gordon McLellan wrote:
>>
>>> I guess I'm saying, if you interpret the name "Serial Attached Scsi"
>>> literally, then the Seagate ES.2 is not an SAS drive - it is not a
>>> scsi drive with a serial interface.  However, if you interpret SAS as
>>> an interface standard, then the interface board determines what the
>>> drive is, more so than its mechanical construction.
>>
>> SAS and SATA use the same physical interface, the drive mentioned
>> is most definitely SATA. Largest SAS drive I have heard of
>> myself is 400GB, same as the max size for FC drives.
>
> No.  No it isn't.  It's SAS.  The platters etc are the same hardware used 
> in the SATA part, but the interface circuitry is native SAS.  Note that 
> they offer the drive in both SATA and SAS variants.
>
> While SATA and SAS are *supposed* to be able to be mixed freely, my vendor 
> has warned me that it doesn't always work out that well.  They have seen 
> compatibility issues using SATA drives on SAS controllers.  So for 
> applications where you want/need a SAS controller but still need big 
> capacity, these are the drives they recommend.
>

Hehe, I think the somewhat confusing part about SAS is that you expect
it to be a SCSI disk and have the corresponding performance level, but
that won't necessarily be the case if its got SATA innards. :)

Ray


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