Comments on: More Bang for Your Buck with PVSCSI (Part 1)

By: Utilization Review Management

Utilization Review Management — Sat, 06 Feb 2010 06:50:07 +0000

This was great….

I saw this really good post today….

By: Passed the VCP-410 with a 481 score! | HyperViZor

Passed the VCP-410 with a 481 score! | HyperViZor — Sun, 31 Jan 2010 17:39:18 +0000

[...] The blog posts from my fellow bloggers are also very useful; I can tell you that I answered one question about the PVSCSI from Scott Sauer's awesome article here. [...]

By: ?

Tue, 01 Dec 2009 21:42:42 +0000

I really wonder why you are seeing such huge differences in performance.

I did some IOmeter testing (With ESX 4.0 non-U1) comparing the LSI logic parallel and pvscsi adapter, using the specifications from the Open unofficial storage performance thread (http://communities.vmware.com/thread/197844?sta...) and saw only very minor differences.
Other posts there with LSI logic parallel and pvscsi suggested a similar behavior, so I'm really a bit confused about how you managed to produce such significant differences.

One thing that bugs me a tiny bit is, if I want to boot up a VM with, say a live Linux for troubleshooting or whatever reason, I would have to change the controller beforehand.

By: Hany Michael

Hany Michael — Thu, 26 Nov 2009 16:50:15 +0000

Great article Scott .. keep them coming!

By: Vladan

Vladan — Thu, 26 Nov 2009 12:08:48 +0000

When I change from buslogic parralel to pvscsi I receive a nice BSOD… that's all… -:(.

I really look forward to see how to fix this for existing VMs…

By: timothy

timothy — Wed, 25 Nov 2009 00:16:57 +0000

Nice info! Seems i'll be using and recommending that pvscsi more often

By: scottsauer

scottsauer — Tue, 24 Nov 2009 19:36:10 +0000

Suttoi, no vmotion is now fully supported with pvscsi. The only limitation that was a show stopper prior to update 1 was the lack of support on the operating system disk.

By: suttoi

suttoi — Tue, 24 Nov 2009 16:04:59 +0000

Are there any limitations imposed on VMs which use the pvSCSI driver?
i.e. more direct connection therefore no vMotion?

By: scottsauer

scottsauer — Mon, 23 Nov 2009 03:35:31 +0000

Thanks Tim! Part 2 I plan on posting how to migrate existing vm's into a PVSCSI config then how to build out new with the F6 option on boot.

Chad,
Thanks for the comments, I was seeing a lot of variation on my tests. I tried to capture the average IOmeter results, but I figured it might have been the Clariion cache. Thanks for the heads up on the host side cache. I would agree that's yet another benefit of the paravirtual driver.
Sad that you have to leave a disclaimer of who you work for on a simple post like this but I guess that is the way it works now a days.

By: chadsakac

chadsakac — Sun, 22 Nov 2009 22:10:32 +0000

Disclosure (I'm an EMC employee)

Scott - we've been doing lots of testing with pvSCSI - it is awesome, as you point out.

The one thing to watch out for is that we've seen a lot of variability in the test results - and it seems (need to triple validate this) that the pvSCSI does some host-side read caching.

That doesn't make it bad (in fact, I would argue that's probably good!), but just FYI.

Personally, I think the pvSCSI is the way to go in most use cases, particularly now that the boot virtual disk limitation has been lifted in vSphere 4 u1.