CentOS - Mar 2008 - C5 64-bit and software RAID 6?

I have a Dell PowerEdge 2950 with 6 SAS disks and a PERC 5/i controller 
what won't do RAID 6.  I plan to have 2 drives as RAID 1 for the OS, and 
the remaining 4 as RAID 6.  Granted the PERC can do RAID 1, I'm tempted to 
do everything via software RAID.  Thus, if anything goes wrong with the 
controller, I just need to obtain a new SAS controller and I'm back up.

I learned my lesson about not using RAID 0 for important data storage when 
a drive goes bad!

What are peoples' performance and reliability experiences with 64-bit
C5's
software RAID, particularly RAID 6?

Thanks.

Scott

Scott R. Ehrlich wrote:
> I have a Dell PowerEdge 2950 with 6 SAS disks and a PERC 5/i controller 
> what won't do RAID 6.  I plan to have 2 drives as RAID 1 for the OS,
and
> the remaining 4 as RAID 6.  Granted the PERC can do RAID 1, I'm tempted
> to do everything via software RAID.  Thus, if anything goes wrong with 
> the controller, I just need to obtain a new SAS controller and I'm back
up.
4 disks in RAID 6? Isn't this a bit overkill? You would use half
the space for RAID checksums.

If it were me, I would:

Partition all drives identically with a 200M partition 1
and the rest as partition 2

Use sda1 and sdb1 in RAID 1 as /boot
Use sd[cdef]1 as swap in RAID 5
Use sd[abcdef]2 as / in RAID 5

You could use RAID 6 for /, but then you're not 100%
safe if you loose disks 1 and 2 simultaneously.

Mogens

-- 
Mogens Kjaer, Carlsberg A/S, Computer Department
Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark
Phone: +45 33 27 53 25, Fax: +45 33 27 47 08
Email: mk at crc.dk Homepage: http://www.crc.dk