A primer on First Class Disks/Improved Virtual Disks

A First Class Disk (FCD), also referred to as Improved Virtual Disk (IVDs), is one of the more recent features in vSphere that may have escaped your notice. FCDs were created to address a particular gap that we have in vSphere at this time. We are well aware that within a vSphere environment, it is currently very difficult to manage virtual disks unless they are associated with a virtual machine. A simple example would be snapshots. Snapshots work at a per VM basis, and to only snapshot a single VMDK rather than all VMDK attached to a VM involves a…

Taking snapshots with vSAN with failures in the cluster

I was discussing the following situation with some of our field staff today. We are aware that snapshots inherit the same policies as the base VMDK, so if I deployed a VM as a RAID-6, RAID-5, or a RAID-1, snapshots inherit the same configuration. However if I have a host failure in a 6-node vSAN running RAID-6 VMs, or a failure in a 4-node vSAN running RAID-5, or a 3-node vSAN running RAID-1, and I try to take a snapshot, then vSAN does not allow me to take the snapshot as there are not enough hosts in the cluster to…

Migrating a VM with snapshots to/from VSAN

In Virtual SAN 6.0, a new snapshot format was introduced called vsanSparse. This improves snapshot functionality by leveraging the new VirstoFS on-disk format used with VSAN 6.0. I had a question recently about what would happen if I migrated a VM with a traditional vmfsSparse/redo log type snapshot. The question was whether or not it would be converted to the new vsanSparse format. Similarly, what if a VM with a vsanSparse snapshot was migrated from VSAN to a traditional VMFS/NFS datastore? Would it also be converted between formats? I decided that the only way was to try it out.

When and why do we “stun” a virtual machine?

This is a question that seems to come up regularly, but I don’t think it appears in any great detail in external facing documentation. The question is “when do we stun (or in other words, quiesce) virtual machines”, why do we do it, and more importantly, how long can a stun operation take? One of our staff engineers, Jesse Pool, put together some really good explanations around the VM stun operation, which I am leveraging for this post. I took some particular interest in this as I wrote a bunch of snapshot posts recently around Virtual Volumes (VVols) so I…

Tintri adds new VM-aware features and VAAI Support

During VMworld 2012 in San Francisco, I had a chance to catch up once again with the team from Tintri. My first introduction to Tintri was at last year’s VMworld, where they received runner-up in the ‘Hardware for Virtualization’ category by TechTarget for best of VMworld 2011. Well this year they went one better, and won the Best of VMworld 2012 Gold award in Hardware for Virtualization. And for good reason. Let’s see the enhancements to the Tintri platform over the last 12 months have brought.