VSAN 6.0 Part 5 – new vsanSparse snapshots

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.

This new vsanSparse snapshot format leverages features of the new (v2) on-disk format in VSAN 6.0, VirstoFS. VirstoFS is the first implementation of technology that was acquired when VMware bought a company called Virsto a number of years ago. You can get an overview of this company from this blog post I did prior to the acquisition.

I’m not going to add to much more to this blog as there are tech notes and white papers now available describing the improvements made with vsanSparse. Of course, with any snapshot technology, there are also some considerations, and these are included in the tech note I wrote on vsanSparse. One final note is to highlight that vsanSparse is not the same as the highly anticipated Virsto native snapshots, but rather vsanSparse is a new sparse format snapshot mechanism that leverage the sparseness of VirstoFS. There is a more detailed explanation in the tech note.

We will be publishing a white paper in the very near future which demonstrates how well these snapshots perform with real life workloads. I’ll update this post when it is available.

[Update] The white paper is now available – click here.

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