Array controller Settings

[ghosking]

Hi

We are having issues with our Exchange 2003 server and have seen high disk activity and also RPC spikes. One thing the Microsoft technet pages has indicated is to look in to the caching options on the array controller.

Currently with have a 50:50 read write cache ratio (see picture). Is there any specific recommendations for Exchanger 2003 server?

[Oleg Koroz]

Server model?
Are any additional cards on the same bus?
Cache size?
Backplane split for duplex? Channels?
And firmware Updates for Controller and HDD

[Andrzej Kowalik]

Hmmm, Microsoft not speak directly to disable write cache, but:
"Reliability
Exchange Server uses a transaction log and associated recovery logic to make sure that there is database consistency if a system failure or an unmanaged shutdown occurs. When the database manager writes to its transaction logs, the database manager must depend on the return of a successful completion code from the operating system as a guarantee that the data has been secured to disk, not just to a volatile cache that will be lost if there is a system failure.

Additionally, the limits of recoverability are determined by the ability of the disk system to make sure that data written to the disk is stored and retrieved reliably. Microsoft recommends that you use disk systems that can detect imminent failures and salvage or relocate affected data when you use Exchange Server.

Microsoft continues to work with other vendors to identify and resolve problems that affect the integrity and recoverability of Exchange Server data. Exchange Server includes several internal mechanisms for detecting and isolating file-level damage to an Exchange Server database. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
314917 (http://support.microsoft.com/kb/314917/) Understanding and analyzing -1018, -1019 and -1022 Exchange database errors"

http://support.microsoft.com/kb/317173/en-us

regards,
Andrzej Kowalik

[ghosking]

many thanks for information so far, attached is a spreadsheet with server config details.

[Igor Karasik]

I guess Microsoft recommend turning off write-back caching, but that was
a long time ago.
I think 50:50 cache ration is good (we use 50:50 on our ML370 G4 servers/SA 6400 Exchange 20003 servers).
I also see recommendations to set 100 percent write
http://www.msexchange.org/tutorials/Optimize-Exchange-2003-Performance-Part1.html
"If your RAID controller has a mirrored, battery-backed, write-back cache, set the ratio to 100 percent write."