SOURCE: Diskeeper Corporation

February 19, 2009 13:40 ET

Virtual Machine Fragmentation: Impact on System Performance

BURBANK, CA--(Marketwire - February 19, 2009) - It's the twenty-first century, and all around us are the signs. Computing power that used to occupy whole floors of buildings now fits in the palm of your hand. A transcontinental phone call that used to take half an hour to connect and cost fifty dollars can now be made instantly for a dollar. A letter to home that used to take a week to arrive can now be sent in seconds. And, servers that used to take up valuable floor space in the computer room can now be made invisible, and several of them can now fit inside a single server box.

Thanks to many novels and movies on the subject over the years, the term "virtual" conjures up images of imaginary worlds made seemingly real, or of created environments floating before us in the air. And in the case of virtual machines, it's seemingly true -- the entire machine exists as an application. How could such a thing be affected by something as backwards as file fragmentation?

The answer is that virtual machines must still make use of that ancient twentieth century hard drive technology. Hard drive partitions are made to appear as entire drives dedicated to the virtual machines, but underneath the "virtual" layer, the hardware is storing files the way it always has, utilizing an entire disk and fragmenting files from all partitions across the whole disk.

Virtual machines have their own I/O requests which are passed along to the host system. Hence, multiple I/O requests are occurring for each file request -- minimally, one request for the guest system, then another for the host system. But in a common fragmentation scenario, especially with virtual servers creating high amounts of disk activity, files will be fragmented into tens, hundreds or even thousands of fragments. Imagine the frantic activity with multiple I/Os for each fragment of each and every file requested. The impact on performance is horrendous.

Many sites have become aware of this problem, and are utilizing fully automatic defrag from Diskeeper Corporation to address it.

Daniel Wagner of Zebra Network Security stated, "Our biggest performance increase was of course seen on our fileservers, including a NAS that stores about 15 virtual servers. If you are going to be running any virtualization on a NAS or direct storage, Diskeeper is a must."

Diskeeper Corporation's proprietary InvisiTasking® technology allows sites to keep up with the hectic fragmentation rates of virtualization. Utilizing only otherwise-idle resources, Diskeeper® software defragments in the background. There is never a negative performance hit from defrag, and performance is always maximized.

So while space-age virtual machines must be tied to ancient hard drive technology, utilize a very modern solution: Diskeeper software with InvisiTasking technology.

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