There is a new snapshot format introduced in VSAN 6.0 called vsanSparse. These replace the traditional vmfsSparse format (redo logs). The vmfsSparse format was used when snapshots of VMs were taken in VSAN 5.5, and are also the format used when a snapshot is taken of a VM residing on traditional VMFS and NFS. The older vmfsSparse format left a lot to be desired when it came to performance and scalability. This KB article from our support team, indicating that no snapshot should be used for more than 72 hours, and snapshot chains should contain no more than 2-3 snapshots, speaks for itself.
I was heavily involved in the documentation effort for VSAN 6.0, but I know that not everyone likes to RTFM, so to speak. What I thought I would do in this post is give an overview of the upgrade process, and highlight some considerations. But I really would urge you to read through the VSAN 6.0 Administrators Guide, and perhaps the VSAN Troubleshooting Reference Manual, especially the sections dealing with upgrades, if you do plan to upgrade from VSAN 5.5 to 6.0. There is a lot of useful information there.
There are four steps to the upgrade process:
Upgrading vCenter Server to 6.0
Upgrading the ESXi hosts to 6.0
Upgrading the on-disk filesystem format from v1 to v2 (VMFS-L to VirstoFS)
Upgrading the components to v2
Items 1 & 2 are outside the scope of this post. Refer to the generic vSphere 6 documentation on how to do those. Items 3 & 4 are done via a new RVC command that we will discuss in more detail here.
I’d met Virsto Software at previous VMworld conferences, but never had a chance to have a meaningful discussion regarding their products and solutions. On a recent trip to the US, I had the pleasure of meeting with Eric Burgener at the Virsto offices in Sunnyvale. He kindly took the time to give me an overview of their Virsto for vSphere 1.5 product.