Windows Aligment - VMDKs

[kopper27]

hi

I've been reading*** about Windows alignment especially Windows 2003 since it looks like Windows 2008 does not need it anymore and the offset is already 1024KB which is good

My questions are:

I am kinda confused is there a recommended offset? 64KB or 1024KB it is much better? or it depends on the app I will run on my windows 2003?

Can I have any # of VMs in my enviromet using different offset 64KB - 1024KB?

thanks a lot guys

***

http://www.tcpdump.com/kb/os/windows/disk-alignment/new-volume.html

http://www.yellow-bricks.com/2010/04/08/aligning-your-vms-virtual-harddisks/

[RParker · Accepted solution]

I am kinda confused is there a recommended offset? 64KB or 1024KB it is much better? or it depends on the app I will run on my windows 2003?

Offset alignment means one thing, that everybody starts on the same foot.

Disk space alignment is chunks of data. If your offset is not the same place where the SAN is, then you have overlap. Overlap causes more writes more reads.

Also Windows 2008 uses GPT disks, different from Windows 2003, that's why the offset is different.

So no you don't NEED to change it, just leave it at 64kb. It just has to be EVENLY divisible by 64K, you remember math class don't you..

[kopper27]

thanks a lot

so basically if my SAN is 64KB I will use VMDKs 64KB right?

still can I have different offset in the same VMFS?

[PaulSvirin]

IMHO, you can use the 64*n KB offset.

In your 2nd link it's written: "For most though, the 2048 sector offset is a safe bet." Here is the key.

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iSCSI SAN software

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