Regular readers will know that I normally blog about the technical aspects of storage, as opposed to doing opinion pieces. However there have been a number of articles published recently questioning the value of VMware’s Virtual Volumes, commonly referred to as VVols. In general, the pieces I have read ask whether or not VVols (or to be more accurate, per-VM granularity feature of VVols) adds value when NFS is already doing per-VM granularity in the form of files. The point that was missed in these pieces is that VVols is so much more than per-VM granularity. I’ve just come back…
In some previous posts, I highlighted how VVols introduces the concept of “undo” format snapshots where the VM is always running on the base disk. I also mentioned that this has a direct impact on the way that we do snapshots on VMs that support VSS, the Microsoft Volume Shadow Copy Service. But before getting into the detail regarding how VVols is different, it’s worth spending some time understanding whats going on when VSS is called to quiesce applications when a traditional snapshot is taken. If you try to research this yourself, you’ll find that there is very little information…
I learnt something interesting about Virtual Volumes (VVols) last week. It relates to the way in which snapshots have been implemented in VVols. Historically, VM snapshots have left a lot to be desired. So much so, that GSS best practices for VM snapshots as per KB article 1025279 recommends having on 2-3 snapshots in a chain (even though the maximum is 32) and to use no single snapshot for more than 24-72 hours. VVol mitigates these restrictions significantly, not just because snapshots can be offloaded to the array, but also in the way consolidate and revert operations are implemented.
There are a couple of key concepts to understanding Virtual Volumes (or VVols for short). VVols is one of the key new storage features in vSphere 6.0. You can get an overview of VVols from this post. The first key concept is VASA – vSphere APIs for Storage Awareness. I wrote about the initial release of VASA way back in the vSphere 5.0 launch. VASA has changed significantly to support VVols, with the introduction of version 2.0 in vSphere 6.0, but that is a topic for another day. Another key feature is the concept of a Protocol Endpoint, a logical I/O…
I pushed this post out a bit as I know that there is a huge amount of information out there around virtual volumes already. This must be one of the most anticipated storage features of all time, with the vast majority of our partners ready to deliver VVol-Ready storage arrays once vSphere 6.0 becomes generally available. We’ve been talking about VVols for some time now. Actually, even I have been talking about it for some time – look at this tech preview that I did way back in 2012 – I mean, it even includes a video! Things have changed…