Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

looking for recommendations on ESX4 OS - VMFS version3:

RAID-5 : matching the stripe size with VMFS block size? (64K, 128K etc)

RAID controller options: "adaptive read ahead, write-back" on PERC 6i

i have read that smaller stipes are good for writes and larger for reads. Since this is virtual env, not sure whats good.

what impact if any has aligning VMFS & data disks in Virtual machines? Appreciate your comments.

share|improve this question

I think that it's more important to know what the vm's will be doing. Are they heavy IO, especially writes?

ESX can be very heavy on disk IO, in fact it's usually the biggest bottleneck. You end up doing a lot of big file copies (creating new guests, cloning and vmotion) and you are combining the disk IO of several servers onto a envirmonment usually reserved for a single server.

SQL Server is particularly write heavy, so on that alone I'd try to use RAID 10.

share|improve this answer
mostly balanced reads, writes this is a test VM server. So not really many big file copies, no vmotion. it is the usual load of Windows OS plus some writes to SQL Server. – John-ZFS Apr 25 '10 at 14:50

If you're using 2003 server, make sure your NTFS partitions are aligned with the underlying storage. Look at for one method. I tend to be lazy and partition 2003 server disks with a Vista, 7 or 2008 server install DVD ISO, and then populate the resulting partitions having booted from the 2003 install media.

If you're going to be running write heavy workloads, I'd benchmark RAID 5 against RAID 10 before you enter production. RAID 5 with multiple concurrent writes can be a performance challenge.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.