ESXi 8.0U3 – UNMAP, vVols

Just a very quick note to let you know Broadcom/VMware finally released 8.0 U3 today. There are a lot of features in this update which you can read about here. I have just two topics to address.

UNMAP

VMware continues the updates to UNMAP functionality in an effort to avoid consequences of their original implementation. This update is a big one as far as preventing UNMAP from overloading your system. With this release you can now instruct VMware to only issue UNMAP commands to a datastore from a set of hosts, or one. Recall the current functionality is that each ESXi host that mounts the same datastore can issue UNMAPs against it up to the priority or fixed amount. So even if you tell VMware you only want 20 MB/s unmapped at once, if you have three hosts attached to that datastore you could actually get to 60 MB/s. This update allows you to set the max number of hosts that can issue UNMAP. See below my example where I instruct VMware to only allow the one host:

This will help immensely. Once you get to 8.0 U3 I suggest you implement it on all datastores using automatic UNMAP.

vVols

Two items here.

First, this release supports vVols in a metro configuration with SCSI devices. We do not support SRDF/Metro with vVols so their support does not change our support.

Second, and this one is more important. VMware has a few very nasty bugs in 8.x that are hitting our vVol customers. They have fixed these bugs in 8.0 U3 but are not currently backporting them. I therefore strongly advise any PowerMax vVol customer that is running vSphere 8.x to upgrade to 8.0 U3 as soon as possible. I know for most customers that is a big ask since upgrades are not simply applied as soon as they come out. But these bugs are particularly problematic. Of course you may never hit them, but it’s best to be safe.