storage drs

Setting the default affinity rule for Storage DRS

Duncan Epping · Feb 7, 2012 ·

On my blog article for yesterday “Rob M” commented that the default affinity rule for Storage DRS (SDRS), keep VM files together, did not make sense to him. One of the reasons this affinity rule is set is because customers indicated that from an operational perspective it would be easier if all files of a given VM (vmx / vmdk’s) would reside in the same folder. Especially troubleshooting was one of the main reasons, as this lowers complexity. I have to say that I fully agree with this, I’ve been in the situation where I needed to recover virtual machines and having them spread across multiple datastore really complicates things.

But, just like Rob, you might not agree with this and rather have SDRS handling balancing on a file per file basis. That is possible and we documented this procedure in our book. I was under the impression that I blogged this, but just noticed that somehow I never did. Here is how you change the affinity rule for the current provisioned VMs in a datastore cluster:

Go to Datastores and Datastore Clusters
Right click a datastore cluster and select “edit settings”
Click “Virtual machine settings”
Deselect “Keep VMDKs together”

For virtual machines that need to stick together you can override the default by ticking the tick box next to the VM

Also check out this article by Frank about DRS/SDRS affinity rules, useful to know!

How cool and useful is Storage DRS?!

Duncan Epping · Feb 6, 2012 ·

I was just playing around in my lab and created a whole bunch of VMs when I needed to deploy to large virtual machines. Both of them had 500GB disks. The first one deployed without a hassle, but the second one was impossible to deploy, well not impossible for Storage DRS. Just imagine you had to figure this out yourself! Frank wrote a great article about the logic behind this and there is no reason for me to repeat this, just head over to Frank’s blog if you want to know more..

And the actually migrations being spawned:

Yes, this is the true value of Storage DRS… initial placement recommendations!

Does SRM support Storage DRS? No it does not!

Duncan Epping · Sep 7, 2011 ·

During VMworld I received multiple questions around support for vSphere Storage DRS with vSphere Site Recovery Manager (SRM), we even had this question during our session and my answer was “Yes it does”. During some of the other sessions presenters stated that it was unsupported. Scott Lowe also mentions recalling the fact that it was mentioned somewhere down the line to be unsupported. Now although the Resource Management Guide for vSphere 5.0 on page 91 currently says it is supported it is not supported. Yes I know I stated it was supported but unfortunately the document is incorrect and the information provided to me was outdated. Although I verified the facts, I was not informed about this change. Hopefully this will not happen again and my apologies for that.

Now lets give the raw facts first, SRM does not support Storage vMotion and SRM does not support Storage DRS. The reason that SRM does not support Storage vMotion (and subsequently Storage DRS) is because it changes the location of the virtual machine without SRM being aware of it. After the location of the virtual machine has changed the VM that was originally protected by SRM will not be protected anymore which can have an impact on your RTO. These are the raw facts. I have requested the SRM team to document this in a KB to make sure everyone understands the reason and the impact.

The question of course is… will it work? My colleague Cormac has tested it and you can read his observations here.

This statement is documented in the SRM releasenotes: http://www.vmware.com/support/srm/srm_releasenotes_5_0_0.html

Interoperability with Storage vMotion and Storage DRS:
Due to some specific and limited cases where recoverability can be compromised during storage movement, Site Recovery Manager 5.0 is not supported for use with Storage vMotion (SVmotion) and is not supported for use with the Storage Distributed Resource Scheduler (SDRS) including the use of datastore clusters.

** update: I followed the documentation which apparently was incorrect. Documentation bug has been filed, should be update in the near future. **
** update: Link to SRM releasenotes with statement added. **

VM with disks in multiple datastore clusters?

Duncan Epping · Aug 9, 2011 ·

This week I received a question about Storage DRS. The question was if it was possible to have a VM with multiple disks in different datastore clusters? It’s not uncommon to have set ups like these so I figured it would be smart to document it. The answer is yes that is supported. You can create a virtual machine with a system disk on a raid-5 backed datastore cluster and a data disk on a raid-10 backed datastore cluster. If Storage DRS sees the need to migrate either of the disks to a different datastore it will make the recommendation to do so.

vSphere 5 Coverage

Duncan Epping · Aug 6, 2011 ·

I just read Eric’s article about all the topics he covered around vSphere 5 over the last couple of weeks and as I just published the last article I had prepared I figured it would make sense to post something similar. (Great job by the way Eric, I always enjoy reading your articles and watching your videos!) Although I did hit roughly 10.000 unique views on average per day the first week after the launch and still 7000 a day currently I have the feeling that many were focused on the licensing changes rather then all the new and exciting features that were coming up, but now that the dust has somewhat settled it makes sense to re-emphasize them. Over the last 6 months I have been working with vSphere 5 and explored these features, my focus for most of those 6 months was to complete the book but of course I wrote a large amount of articles along the way, many of which ended up in the book in some shape or form. This is the list of articles I published. If you feel there is anything that I left out that should have been covered let me know and I will try to dive in to it. I can’t make any promises though as with VMworld coming up my time is limited.

Once again if there it something you feel I should be covering let me know and I’ll try to dig in to it. Preferably something that none of the other blogs have published of course.