I posted a few months back about ESXi queue depth limits and how it affects performance. Just recently, Pure Storage announced our upcoming support for vSphere Virtual Volumes. So, this begs the question, what changes with VVols when it comes to queuing? In a certain view, a lot. But conceptually, actually very little. Let’s dig into this a bit more.
So I am in the middle of updating my best practices guide for vSphere on FlashArray and one of the topics I am looking into providing better guidance around is ESXi queue management. This breaks down to a few things:
Array volume queue depth limit
Datastore queue depth limit
Virtual Machine vSCSI Adapter queue depth limit
Virtual Disk queue depth limit
I have had more than a few questions lately about handling this–either just general queries or performance escalations. And generally from what I have found it comes down to fundamental understanding of how ESXi queuing works. And how the FlashArray plays with it. So I put a blog post together of a use case and walking through solving a performance problem. Explaining concepts along the way.
This is a simple example to explain how queuing works in ESXi
Mileage will vary depending on your workload and configuration
This workload is targeted specifically to make relationships easier to understand
PLEASE do not make changes in your environment at least until you read my conclusion at the end. And frankly not without direct guidance from VMware support.
I am sorry, this is a long one. But hopefully informative!
If you prefer a video, here is my 1 hr VMworld session that goes into depth on what I write below: