RAID-5 and Oracle Performance

Agreed... combinations of RAID-5 with a write-back Hardware RAID controller and RAID-1 work good. Of course, RAID 0+1 is the absolute best all around RAID configuration but it's expensive because every disk is mirrored besides being striped. No write penalty because there is no parity kept. Especially when restoring a 50GB database and a VP with a stopwatch is looking over your shoulder wondering when the production database will be ready. Also, no degradation when a single RAID-5 disk goes bad or is offline from the Raidset.
We are using DEC Alpha 4100 based servers with HSZ-40 (32MB Cache) and HSZ-70 (128MB) RAID controllers.

We just received the DEC HSZ-70 Enterprise Storage Array with about 54GB of 9GB disk. (7 - 9GB disks) We were eating 2GB and 4GB disk up as if they were candy.

/diskA-r5 - 54GB (9GB x 7 Disks) - Oracle data and indexes - tablespaceA -
DatafileA

My UNIX admin wants to throw our Oracle Manufacturing database on one single giant 54GB RAID-5 array. I don't really agree. Because Oracle data and indexes won't really be separated from disk drive heads. I would rather have 2 separate 27GB RAID-5 arrays. Example:

/diskA-r5 - 27GB (9GB x 4 Disks) - Oracle data - tablespaceA - datafileA
/diskB-r5 - 27GB (9GB x 4 Disks) - Oracle indexes - tablespaceB -
datafileB

Therefore when queries touch both the data and indexes - Physically separate drive heads on 2 separate arrays will not contend with one another. They will execute more in parallel.

Does this make sense to anyone? What do you all think?

jeff.sherveynospam_at_us.landisstaefa.com
Take the nospam off my username to reply...

Jeff Shervey
Landis and Staefa - Buffalo Grove, IL
Oracle/Ingres DBA - Oracle Financials Received on Thu Jan 29 1998 - 00:00:00 CST