[CentOS] RAID5 or RAID50 for database?

Thu May 22 16:12:24 UTC 2008
Guy Boisvert <boisvert.guy at videotron.ca>

Jason Clark wrote:
> You're going to need two RAID controllers and 6 drives to do RAID 50.
> RAID 50  will be faster, but costs more in drives and controllers.
> Jason
> www.cyborgworkshop.org
> mcclnx mcc wrote:
>> we have DELL 6800 server with 12 internal disks in it.  O.S. is CENTOS
>> 4.6 and SCSI control card is PERC 4e/di.
>> We plan to configure 4 disks (5,8,9,10) as RAID5 or RAID50.  This
>> logical volume will be use as file systems and store database backup files.
>> Can anyone tell me which one is better on performance?

1st, Jason, please do not top post!  It makes life harder in mailing lists.

(item 2, "Guidelines for CentOS Mailing List posts")

You do not need two (2) raid controllers unless you want to have
redundancy at the controller level.  Adaptec, 3Ware, etc do RAID 50.
For RAID 50, you need at least 6 disks.


For database, i'd go with RAID 10.  As pointed out Joseph in a previous
post, RAID 5 rebuilding would slows the array down.

As for RAID 10, i didn't make extensive benchmarks but here are the
rough results i got with Adaptec 3405 and four (4) Seagate 15K SAS drives:

RAID 5: Read = 170 MiB/s
	Write =  135 MiB/s

RAID 10: Read = 170 MiB/s
	 Write = 160 MiB/s

And the difference gap (write) should increase in favor of RAID 10 as
one add disks (provided that the controller use more PCI-e lane than the
Adaptec 3405 which use 4 lanes or even using the PCI-X bus).  RAID 5
uses XOR calculation.

Guy Boisvert, ing.
IngTegration inc.