My Windows Home Server was up and running for a while. Only recently due to itchy fingers, I decided that a defrag may do it some good. Of course, I remembered MS has warned not to use the build in defrag. So there is 2 obvious choices out there with the Made for WHS label. Diskeeper 2008 and PerfectDisk 2008. Ok, the mistake I made was using the Server Edition trial instead of using the WHS version. What happened?
Due to the VSS or shadow copy function, when the defrag tries to move the file, VSS thinks the files has been changed and tries to keep track of the changes. Now you see the problem? So much so that the WHS actually locks up due to a deadlock.
But searching on the MS Forum :
"As all defragmenters use Microsoft's defrag APIs, until MS makes changes in those APIs or changes how VSS works so that it can detect defrag activity on 4k cluster size drives as they do with 16k> cluster size drives, you will always run the risk on Vista, 2003, 2008 and Home Server of restore points/shadow copies being purged when you defragment. The best that defrag vendors can try to do is work around this by detecting if a VSS enabled drive has a "non-optimal" cluster size and try to do something to mitigate file movement..."
Wow! Ok, just all the mumbo jumbo. The conclusion is that until something can be done about 4k cluster, its not advisible to defrag it at all. And you can change it to 32k cluster, but all hell WILL break loose making your whole WHS crash.
Conclusion. DO NOT USE A DEFRAG software in your WHS. Not until it can fully support the VSS and 4k cluster. The so-call WHS version of these software just skips the drive which are 4k cluster, which is not really what you wanted in the first place (or paid for).