Dallas Data Center

IT professionals know that server disks fragment. As server disks fragment, the performance and file access can slow down. Most administrators just set a schedule to defrag the server when usage is low and keep moving. Virtualization has brought another problem into the mix. We can defrag our virtual machines, but what about the host drives?

Eric Siebert wrote a blog that explains the pro’s and con’s of defragging the host drives vs. the virtual machine drives. It seems as the best solution to defragging is timing. Defragging causes high I/O on the host and the storage attached. If you defrag multiple virtual machines at the same time then it can cause serious lag time in the servers and possibly lockups. Another time to avoid the defragmenting time is during a snap. If the VMDK is being snapped or cloned at the time, there is an excessive amount of changes happening and the snap will grow larger than needed. Scheduling during off-time without any other maintenance being performed is the best time to defrag the virtual machine.

Defragging the host platform is not necessary because the way the files are written, into the folders, the OS itself does not fragment. Additionally, there are no defragmenting tools on the market for the host OS.

As our server OS’s change and become more efficient, the defrag argument will diminish, but until then, proper maintenance planning of your virtual environment will deliver success.

References

http://itknowledgeexchange.techtarget.com/virtualization-pro/defragmenting-virtual-machine-disk-files/?track=NL-921&ad=690189&asrc=EM_USC_5929440&uid=8473735