Monitoring Automatic VMFS-6 UNMAP in ESXi

With VMFS-6, space reclamation is now an automatic, but asynchronous process. This is great because, well you don’t have to worry about running UNMAP anymore. But since it is asynchronous (and I mean like 12-24 hours later asynchronous) you lose the instant gratification of reclamation.

So you do find yourself wondering, did it actually reclaim anything?

Besides looking at the array and seeing space reclaimed, how can I see from ESXi if my space was reclaimed?

Continue reading Monitoring Automatic VMFS-6 UNMAP in ESXi

In-Guest UNMAP, EnableBlockDelete and VMFS-6

EnableBlockDelete is a setting in ESXi that has been around since ESXi 5.0 P3 I believe. It was initially introduced as a way to turn on and off the automatic VMFS UNMAP feature introduced in 5.0 and then eventually canned in 5.0 U1.

The description of the setting back in 5.0 was “Enable VMFS block delete”. The setting was then hidden and made defunct (it did nothing when you turned it off or on) until ESXi 6.0. The description then changed to “Enable VMFS block delete when UNMAP is issued from guest OS”. Continue reading In-Guest UNMAP, EnableBlockDelete and VMFS-6

In-Guest UNMAP and VMware Snapshots

Here we go with another in-guest UNMAP post. See other posts here:

https://www.codyhosterman.com/pure-storage-vmware-overview/flasharray-and-vmware-best-practices/space-reclamationunmap/

I was asked the following question the other day “does in-guest UNMAP work when snapshots exist?” To save you a long read: it does not work. But if you are interested in the details and my testing, read on.

My initial answer was “no” but I thought about some changes in VMFS-6 and reconsidered. If you refer to the vSphere 6.5 documentation you can see this change for VMFS 6:

“SEsparse is a default format for all delta disks on the VMFS6 datastores. On VMFS5, SEsparse is used for virtual disks of the size 2 TB and larger” Continue reading In-Guest UNMAP and VMware Snapshots