Comments on: Don’t use VMware Raw Device Mapping (RDM) for performance, but ..

By: admin

admin — Tue, 10 Jan 2012 07:08:11 +0000

Hi Brent,

svmotion should do and it ask you if you want to convert to VMDK files or not. If its physical RDMs then converting to VMDK files is actually the only option it give.

Regards,
Eiad

By: Brent

Brent — Thu, 05 Jan 2012 19:40:51 +0000

Hello -

Nice write up. I’m interested in migrating some VMs using RDMs to standard virtual disks. Do you know of any snazzy tools out there to that can do this in the background? I had a vague recollection that this could be done via svmotion, but I’m finding no proof of that now. I have used guest OS solutions to sync data from old:new volume in the past, but there’s always a brief outage at cut-over with these solutions. Would love to figure out a way to do it live.

Thanks!

Brent

By: admin

admin — Tue, 29 Nov 2011 07:13:15 +0000

I am glad it was helpful errsta. VMFS 5 performance was quite improved and its closer and closer to what RDM is giving that its not much noticeable.

By: errsta

errsta — Sun, 27 Nov 2011 00:22:08 +0000

Thanks for this post. I’ve referenced it too many times to count. Do the recommendations change with VMFS5?

By: Eiad Al-Aqqad

Eiad Al-Aqqad — Thu, 19 May 2011 16:36:34 +0000

Hi Ashraf,

I thought it was worth mentioning that Oracle RAC is officially supported on vSphere. If you would like any more info just e-mail me.

By the way I am one of the Systems Engineers covering around your region, so feel free to contact me if you need any official VMware help around this and I can hook you up with the right contacts.

Regards,
Eiad Al-Aqqad

By: Ashraf Zorkani

Ashraf Zorkani — Tue, 17 May 2011 20:24:53 +0000

Hi, This is was a good conclusion for me as I am studying the feasibility of hosting Oracle RAC over ESX 4.1. I am trying to build a workable scenario on how this will be done, taking in consideration all other VMware features such as server vMotion and other stuff!.

By: Eiad

Eiad — Fri, 29 Oct 2010 15:11:50 +0000

Hi Ben,

Thanks for the note. I am not sure how I missed that & I fixed it now as follow:

* No migrating VMs with physical mode RDMs if the migration involves copying the disk (Storage VMotion)
* No VMotion with physical mode RDMs when any clustering software is used.

Regards,
Eiad

By: Benjamin Troch

Benjamin Troch — Mon, 25 Oct 2010 05:27:16 +0000

Hi, Vmotion is possible with physical and virtual RDM’s. You might want to change that on the post.
Cheers, Ben

By: VCAP-DCA Objective 1.1 : Implement and Manage Complex Storage Solutions

VCAP-DCA Objective 1.1 : Implement and Manage Complex Storage Solutions — Sun, 12 Sep 2010 22:31:51 +0000

[...] good read is the blog here which discusses why RDM’s should probably not be used for performance purposes. It’s main [...]

By: Jeff Snavely

Jeff Snavely — Sat, 24 Jul 2010 00:18:30 +0000

I know it probably didn’t effect the outcome, but their choice of disk configuration strikes me as really odd. I am left wondering why you would choose that for your test configuration.