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analyst7
Contributor
Contributor

Defragmenting .vmdk files and virtual machines

I'm running Vi3 3.01.

What are the best practices for defragmenting the following:

LUNS - VMFS-3 volumes specific commands or rely on SAN vendor defrag tools?

.vmdk files - (is vmware-vdiskmanager still applicable?)

Windows virtual machines - Run Defrag within the windows hosts?

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MR-T
Immortal
Immortal

You don't defrag VMFS volumes. Because you're dealing with such big files, they don't become fragmented in the same way as Windows boxes.

You can still run defrag inside Windows guests to get the best out of the vm's.

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acr
Champion
Champion

As MR-T say's leave the VMFS Partition, but you can and we do run defrag tools for the VM's..

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RParker
Immortal
Immortal

OK, after doing some research on this subject, I can tell you..

There isn't a defrag tool for Linux. Or for Unix either for that matter. Contrary to popular belief \*ALL* file systems (not even going to address an argument here, you are wrong even before we get started) get fragmented. \*ALL*.

Now, the deal is with VMFS, they don't get fragmented as often BECAUSE the files take up space initially, and grab a contiguous file space. Then they don't move. Windows gets fragmented, because they change a lot and move around, and they are much smaller files, so in essence you shouldn't \*NEED* to defragment. However, over time, months or years, as you delete VMDK files, resize, move them to other places, etc.. the VMFS volume \*WILL* be subject to fragments..albeit, even after a few moves minimal fragmentation.

It would take lots and lots of moves, and by then there will be ESX 5 or whatever, and you will be migrating to a new machine or ESX by then anyway.

In short: Don't worry about defragmenting VMFS, only concentrate on Windows NTFS volumes.