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Re: [school-discuss] Re: use on Dell

Karsten M. Self wrote: 
on Fri, Mar 25, 2005 at 02:47:24AM +0200, Michael Shigorin (mike@xxxxxxxxxxx) wrote:

On Thu, Mar 24, 2005 at 04:55:44PM -0700, cdmiller wrote:

Current Poweredge 2650's use an adaptec RAID card for which the
Linux 2.6 drivers are unstable and slow.


Hm, all the specs a quick search turned up seem to tell it has
"Adaptec 7899" which is perfectly a hardware controller albeit not
RAID-capable on itself IIRC.  Maybe Dell stacked something on top of
that or did a different controller (most likely "HostRAID" junk or
79xx series), if that's the case then just turn off HostRAID option in
its BIOS.

Building software RAID on top of those worked just fine for me even
with 2.4.2x kernels (three years ago 7899, last fall 79xx).  (I still
look forward to build the first production server using 2.6.x series
but that will be done this year if things go right)



A friend suggests that Dell's "PERC" RAID controllers may be an issue.
In part on account that 'PERC' (not sure what it stands for -- 'CERC'
was "cheap electronic raid controller") covers a multitude of sins.


The 7899 is not a RAID controller.

The PERC RAID controllers shipped in recent Poweredge 2650's are Adaptec using the aacraid driver. Older PERC controllers were Megaraid. Dell has indicated they are moving back to Megaraid because of the problems with the Adaptec stuff. We will be pressing them shortly to replace our Adaptec PERC's with Megaraid PERC's, and be looking seriously at other vendors at our next server roll over.

For what it's worth the latest 2.4 kernels are stable on the Adaptec RAID, but performance is abysmal, software RAID performs as well as the Adaptec RAID hardware.

- cameron