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I am considering expanding my single ESXi server set-up with a SAN and another ESXi server, because I am planning to update the Windows Server 2003 virtual machines to Windows Server 2008. The servers will run 20 virtual machines together.

  • NAS: X3450, 4GB, 8x1TB Software RAID ZFS, FreeNAS on USB disk
  • ESXi: X3450, 8GB, flash disk
  • ESXi: X3450, 8GB, flash disk

What raid should I use for this purpose? RAID 6, 10 or 50? Would fault tolerance work with this set-up? And is such a SAN/NAS-setup recommend for usage with ESXi servers?

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up vote 1 down vote accepted

I personally would use RAID10. Assuming since they are 1TB drives they are SATA drives its the only way you're going to get the performance you're going to need to run 20 VM's concurrently. I'd say 8 drives is a bare minimum, but at some point you may outpace them. RAID 10 is going to be N (number of drives) / 2 and will probably yield about 3.6-3.7TB usable space for VM's.

Am I also seeing here that you're going to try and run 10 Windows 2008 VMs per ESXI host with only 8GB of RAM? I think you're going to see a larger performance issue there then in contention for disk.

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To more directly answer your question... I think you'll be pushing it, and this setup will not work too well if any of those VM's is disk intensive. Your ESX hosts are also short on memory. – SpacemanSpiff May 27 '11 at 1:53
Wow, yeah. I wouldn't put anything less than 4GB of RAM in any Win2K8 server, regardless of role or purpose. – gravyface May 27 '11 at 2:07
@grayface - I agree, I've gone lower (2GB) for a secondary domain controller, but if it holds any significant role, 4GB minimum, 48-64GB of RAM would be the sweet spot here. VMware should do memory swapping, but its not THAT good. – SpacemanSpiff May 27 '11 at 2:09

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