Author: NetworkAdminKB.com
Created: 2010-06-22
Modofied: 2011-11-06
Issue:
Some times the Disk IO of a VM becomes very slow for no apparent reason. This can be especially noticeable during backups using VCB or other utility that backs up the entire VMDK file.
Cause:
Internal file fragmentation of the OS files inside the VMDK has occurred. Also, fragmentation of the VMDK file may have occurred on the VMFS or NFS file system.
Solution:
Just like normal hard drives you should regularly run defragmentation tasks of the hard drives by the OS hosted on the Virtual Machine (VM). You should do a Storage vMotion to defragment the VMDK file.
Steps
1) Run a disk defragmentation utility inside the Guest OS.
a. Schedule this to happen daily, weekly, etc.
2) Use Storage vMotion to create a new VMDK file on a different LUN
a. Repeat the process if you need to get the VMDK back to the same LUN.
Article ID: 443, Created On: 11/6/2011, Modified: 11/6/2011