Hello
Here are the answers to your questions :
First:
Q: VMFS3 does NOT need to be aligned :
A: The default offset of VMFS3, when created with the Virtual Infrastructure Client or VMware vSphere Client, is 128 blocks by default, which does not result in misaligned I/O. But keep in mind that here we are talking about the alignment of the VMFS file system on top of NetApp file system WAFL
Q:Windows 2008 VMs do NOT need to be realigned?
A: Windows 2008 VM's use GPT disks instead of MBR. So They do not need to be realigned after being created, but if you are moving a 2k8 VM from VMFS 2 or doing a P2V you probably need to realign your VMs
Second :
There are three levels of alignment -
1 - Guest OS
2 - VMFS
3 - Netapp
Q: When you run the MBRAlighn tool - does the tool work at layers 2 and 3?
A: Actualy it works on the -flat.vmdk file (Guest OS HDD) trying to fix the starting offset for your VM
Three :
Q:Would the following solution be valid to align disks
- Create a New VMFS using the VS Client
- VMotion off the VMs to the new datastore
A: No , thats not a resolution for realigning the disks . Alignment should occure on the starting offset of the guest OS (-flat.vmdk files)
Four :
Q: There are many posts about the true benefit of aligning disks. It would appear that only high IO VMs would benefit from Disk Alignment? Is this true?
A: No , Aligning misaligned VM's will increase the overall performance of the storage system not just the VM's with high I/O
Five :
Q: How can I confirm which of my VMs have alignment issue and how can I also validate that the Netapp [3270] does indeed have IOP overhead BECAUSE of disk alignment?
A: Using NetApp MBRAlign tools you can find out which VMs are misaligned ( MBR tools are no part of the VSC 2.1.1 which you can download from the NOW site for free)
Also here is a link to Best Practices for File System Alignment in Virtual Environments
