Align your partitions with VMware Converter 5.0 Beta

Update: VMware released the GA version of 5.0 and you can download it here.

A few days ago VMware released a significant update to their standalone converter utility, Converter 5.0 beta (download here). One of the cool new features is the ability to re-align partitions. By default Windows Server 2003 and Windows XP do not have properly aligned partitions. This can cause addition IOs and poor VM performance. Windows Vista and Server 2008 and later are smarter and automatically align partitions on a 1MB boundary.

So I decided to try out the new feature and verify that a conversion process did in fact align the partitions. To perform the test I already had a Server 2003 VM in VMware Workstation 7 that had an improperly aligned partition:

Here you can see a starting offset of 32,256 bytes which is 31.5KB. No good! You ask how did I get that information? Simple…from a command prompt type:

wmic partition get blocksize, startingoffset, name, index

Next I fired up Converter 5.0, ran through the wizard to convert it to an ESXi VM, and saw this nifty screen:

The ‘create optimized partition layout’ appeared when I selected a volume copy option. Whoohoo! I ran through the rest of the wizard, waited 4.5 hours (gotta be a beta bug to take this long), and viola, ended up with a newly converted VM on my ESXi host. Now did the converter actually work? Let’s see:

By George, yes the starting offset is now divisible by 32K. You can now sleep better knowing that your disk subsystem is working as efficiently as it can. This tweak can be really important in a Windows XP VDI environment where there’s a lot of disk IO and any savings can be substantial when multiplied by hundreds or thousands of VMs.

If you want to get really fancy and change the NTFS cluster size during the conversion process, you can click on the Advanced button in the figure above and tweak as shown below: