Well, I guess you would expect Raxco Software to tell the world that disk defragmentation and free space consolidation in guest systems reduce disk latency and therefore helps improve your virtualization performance. After all, that’s the goal of PerfectDisk vSphere and PerfectDisk Hyper-V running in virtualization environments.
But did you know that VMware recommends doing this?
Even Storage I/O Control (SIOC) cannot thoroughly alleviate the disk latency problem. SIOC improves latency by throttling throughput. However, placing limitations on the HBA-LUN queues treats the symptoms of latency but not the root cause.
#2 After Increasing VM Memory
Defrag is actually high on VMware’s list, too, the second point of its recommendations for improving disk I/O performance in the VMware vSphere 5.1 Documentation Center:
“Defragment the file system on all guests.”
Disk latency is the lag time between when a read/write operation is requested and when it completes, and VMware and EMC tell their customers that defragmenting can go a long way to improving virtual guest performance.
We have a new whitepaper that details all this in more detail. Download whitepaper: VMware Recommends Defragmenting Guest Systems to Reduce Disk Latency