question regarding defragmentation HP EVA and vmware

[ROBERT LEE]

I'm interested in everyone's take on disk defragmenation(e.g. diskeeper 10) and running defrags on san attached drives.
I've been told by hp's support not to use diskeeper on san attached drives.
Diskeeper says you should..

We are also using vmware esx server using raw lun's . The vmdk files are flat files so I'm not sure if those need to run defrags as well.

There's no 1 specific article from hp on this..
Any suggestions?

[Sheldon Smith]

As long as the free space ratio is "small", and there is a fair degree of file creation/expansion/deletion, I would expect *any* container, whether a HDD, Vdisk or vmdk, would have fragmentation of any files *contained within*. How much performance would be gained by running a defragmenter is the real question. Make a bunch of fragmented files within a Vdisk and then use EVAperf to monitor performance while hitting it with something like IOmeter. Then defrag the files and check performance again. Given the faster transfer rate of a Vdisk compared to an HDD, it may be a non-issue.

I take it from your context, a vmdk file is a container of a virtual system? While the vmdk file itself sounds like a big, flat contiguous file, I take it there are files within? Presumably those could get fragmented. Again, performance improvement before and after defragmenting is the real issue.

[ROBERT LEE]

Thanks sheldon for your feedback.
the vmdk is a flat file which holds the guest v.m's in vmware. the vmdk is resident on a raw l.u.n.
I'll try running commandview evaperf on a low usage server.