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We're setting up a SQL2008 system with the following virtual disks (not including the OS/Apps volume):

RAID10 Data
RAID1 Logs
RAID1 TempDB

Any recommendations as to how we should setup the RAID controller cache settings for each of these three VDs? The options are:

Write: write-back(WB) / write through(WT)
Read: read ahead(RA) / adaptive read ahead(ARA) / No Read ahead(NRA)

The RAID controller (512MB cache) has a battery backup unit.

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Why RAID 1 for TempDB? If you're allocating a RAID volume to it, you want it to be fast... but you shouldn't care about losing it, since it's only used for temporary operations. That's one of the few cases where RAID 0 would make sense. –  Massimo Jun 21 '10 at 22:22

3 Answers 3

Definitely use write cache for transaction logs; they're always written and almost never read.

And, if they get actually read, this is done sequentially, so a read cache would be completely pointless.

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I'd say.

Logs: NRA & WB
Database: (ARA or NRA) & WB
tempdb: (ARA or NRA) & WB
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I'd be tempted to switch off write caching altogether but use 100% of your cache for ARA - but then again I'm quite paranoid about transactional integrity and don't fully trust BBWC - you may have more faith.

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