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.

Heads Up! ATS Miscompare detected between test and set HB images

I’ve been hit up this week by a number of folks asking about “ATS Miscompare detected between test and set HB images” messages after upgrading to vSphere 5.5U2 and 6.0. The purpose of this post is to give you some background on why this might have started to happen. First off, ATS is the Atomic Test and Set primitive which is one of the VAAI primitives. You can read all about VAAI primitives in the white paper. HB is short for heartbeat. This is how ownership of a file (e.g VMDK) is maintained on VMFS, i.e. lock. You can read…

vSphere 6.0 Storage Features Part 4: VMFS, VOMA and VAAI

There was a time when VMFS was the only datastore that could be used with ESXi. That has changed considerably, with the introduction of NFS (v3 and v4.1), Virtual Volumes and of course Virtual SAN. However VMFS continues to be used by a great many VMware customers and of course we look to enhance it with each release of vSphere. This post will cover changes and enhancements to VMFS in vSphere 6.0.

vSphere 5.1 Storage Enhancements – Part 1: VMFS-5

Welcome to the first in a series of posts related to new storage enhancements in vSphere 5.1. The first of these posts will concentrate on VMFS. There are two major enhancements to VMFS-5 in the vSphere 5.1 release. VMFS File Sharing Limits Increase Prior to vSphere 5.1, the maximum number of ESXi hosts which could share a read-only file on a VMFS filesystem was 8. This was a limiting factor for those products and features which used linked clones. Linked Clones are simply “read/write” snapshots of a “master or parent” desktop image. In particular, it was a limitation for vCloud…