Kenneth.Fisher (1/11/2012)
GilaMonster (1/11/2012)
Best is 10 everywhere. If that's too expensive, then 1 or 10 for log and 5 for data (and 10 for TempDB)RAID 5 is terrible for logs because it has a high write overhead. Tran logs are write-heavy, not read-heavy.
I had thought that RAID 5 had better write performance than RAID 0? Although I have been reading comments in both directions.
No. RAID 5 has about the worst write performance of the common RAID levels because of the need to compute and then write parity. (though no one would ever consider RAID 0 for a database)
RAID 0, a write operation is a single operation. RAID 5 (let's say 4 stripes), a write operation is a write, potentially 1 or 2 reads and then a second write for the parity stripe)
There's a good overview of the RAID levels and more in chapter 2 of this: http://www.simple-talk.com/books/sql-books/troubleshooting-sql-server-a-guide-for-the-accidental-dba/
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability