Jul 08, 2011

What's a dynamically-expanding drive? Is it better than a fixed-size drive?

When building a VM, I'm asked if I want to use a dynamically-expanding drive or a fixed-size drive. Is one better than the other?


I have mine set up as a fixed-drive because I've had issues in the past with the dynamic drives.


Because dynamic drives expand as needed, sometimes you get error messages when you try to save something large to the existing drive. I've had it tell me the drive was out of room. But if I added a smaller file, it seemed to expand a bit more after that.  It seems that the flexibility of the dynamic drives don't expand "on demand" as you would think that it should.


If I were you, I'd go with the fixed-size drive to save yourself some headaches.


There used to be some performance benefits to using a fixed-size drive in an VM because you don't have to worry about the drive size changing while the VM server is running. That's probably not the case though with updated VMWare and Microsoft virtualization products, which are better optimized for dynamic allocation.

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