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vSphere 5 Top 10: VMFS-5 at #3

If you've been reading this blog long enough, you know by now that I'm a big fan of VMFS. So, it should come as no surprise that VMFS-5 landed in the No. 3 spot on this countdown.

VMFS is a purpose-built file system optimized to run virtual machines. One of the big drawbacks of VMFS-3 was its size limitation of 2TB. With the introduction of the vSphere APIs for Array Integration, it was simply a matter of time before that limitation was lifted. VAAI has several useful features, but one in particular is more relevant to our current discussion: VAAI offloads SCSI reservation from the hypervisor onto the storage array, thereby significantly enhancing the performance of the VM in general.

VMFS-5 now supports datastores of up to 64TB in size, thereby stripping NFS from its only strategic advantage as far as I am concerned. The other feature enhancement that is now enabled within VMFS-5 is the ability to leverage VAAI with thin provisioning and deliver automatic free space reclamation. This is huge. Prior to this version of VMFS, many did not know that when you use thin provisioning and as you start deleting data, you need to go back and reclaim that free space. Well, the problem was that it had to be done manually. And so for those who did know about the free space that could be reclaimed probably had some manual methodologies or scripts that reclaimed the free space. Now, you will be happy to know that another annoying task has been removed from your to-do list and has been automated.

Now, I am sure the last two features in the countdown are probably going to be easy to guess. So, this time a new question: Between Storage DRS and the new High Availability, which one is your top feature and why?

Posted by Elias Khnaser on 08/18/2011 at 12:49 PM


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