Thank you for your thorough input. In our case this is not a bottleneck I am working on. We are getting ready to upgrade our Exchange 5.5 system to Exchange 2000 on new servers. We have the RAID 0+1, numerous fast fiber-attached spindles, fast log drives, etc. The question came up because if these parameters are going to be modified, now (when I have not yet gone production) is the time to do it.
-----Original Message----- From: Webb, Andy [mailto:[EMAIL PROTECTED]] Sent: Thursday, June 20, 2002 10:08 AM To: Exchange Discussions Subject: RE: Allocation Unit (Cluster) Size Question You might consider the book "Scaling Microsoft Exchange 2000: Create and Optimize High-Performance Exchange Messaging Systems" by Pierre Bijaoui from Comp^h^h^h^hHP. There are also a couple MEC presentations around that he did that dive into this pretty thoroughly. Correct tuning of your disks can result in up to a 4x I/O delta. Now, not all of this is done in stripe size; part of it is in the RAID level you choose and the number of spindles. You may find that just adding a couple more spindles makes more difference than any chunk/stripe size changes. Don't focus as much on the exchange database drive though. Most of the activity there is reads and they're cached pretty efficiently by the OS. You can note that the EDB file grows in 1MB chunks, so perhaps that's a reasonable number to work with. If you want to impact perceivable performance, tune the log drives to improve the synchronous write performance. Also note that if you're bottleneck is not the drives, no amount of I/O improvement will change the user experience. In other words, if your existing disks support N I/O operations per second and your users are only driving it to N/4, improving to 2N makes no difference to the users. ======================================================= Andy Webb [EMAIL PROTECTED] www.swinc.com Simpler-Webb, Inc. Austin, TX 512-322-0071 -- Eating XXX Chili at Texas Chili Parlor since 1989 -- ======================================================= -----Original Message----- From: Martin, Jon [mailto:[EMAIL PROTECTED]] Posted At: Monday, June 17, 2002 11:57 AM Posted To: Microsoft Exchange Conversation: Allocation Unit (Cluster) Size Question Subject: Allocation Unit (Cluster) Size Question Exchange writes to the database in 4k pages. This being the case, does it not make sense to format database drives in 4k Allocation Units (clusters)? And beyond that, since my RAID controller gives me the ability to control the stripe size, shouldn't make this 4k also? Get everyone (database, OS and hardware) in 4k harmony, so to speak. On a similar track regarding transaction logs, if we have valid information as to the average size of messages in our system, would there be a performance boost by configuring the transaction log drive to use clusters and stripes close to (but a little bigger) that the average message size? Or, do I have no clue as to how these things work (always a possibility)? Thanks . . . _________________________________________________________________ List posting FAQ: http://www.swinc.com/resource/exch_faq.htm Archives: http://www.swynk.com/sitesearch/search.asp To unsubscribe: mailto:[EMAIL PROTECTED] Exchange List admin: [EMAIL PROTECTED] _________________________________________________________________ List posting FAQ: http://www.swinc.com/resource/exch_faq.htm Archives: http://www.swynk.com/sitesearch/search.asp To unsubscribe: mailto:[EMAIL PROTECTED] Exchange List admin: [EMAIL PROTECTED] _________________________________________________________________ List posting FAQ: http://www.swinc.com/resource/exch_faq.htm Archives: http://www.swynk.com/sitesearch/search.asp To unsubscribe: mailto:[EMAIL PROTECTED] Exchange List admin: [EMAIL PROTECTED]
