I’ve been test driving a script called “mbrscan” for a while now. Today I noticed that this script had already been released a couple of weeks ago. The cool thing about the script is that you can check the alignment of the VM’s filesystem from the outside. The script runs directly on the service console of ESX. NetApp’s Nick Triantos describes it as follows:
There’s a new utility that has been added, called mbrscan. The purpose of mbrscan is to identify whether or not a VM has properly aligned partitions. The script will run successfully under two conditions: a) The VM is powered off b) the VM has VMsnaps. The script will error out if none of the above two conditions are satisfied simply because the VMDK(s) are locked.
This can be very useful to identify possible performance issues within just a matter of seconds. Combine this command with “vmware-cmd” to create and remove snapshots and you’ll have the results for you entire environment within minutes.
Now that you just received your results the real question would be:”How am I going to modify this without destroying the data?”
At this point in time that’s not possible. But I know NetApp is working on a tool called “mbralign”. This tool will make it possible to align the filesystem from outside the VM.
The mbrscan tool is part of the “Unified Host Utilities Kit” which reached version 5. The toolkit isn’t available for everyone, you will need a now.netapp.com/ to be able to download it.
UPDATE: MBRSCAN is a binary not an editable script, and the script version has been floating around for a while now…