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VMWare DRS is not enabled

Posted on 2013-11-04
Medium Priority
Last Modified: 2013-12-15
Hi All,

I have been give control of an ESX cluster. I was asked to create 2 servers which would share RDM's, i created the virtual servers and attached the RDM's to both machines making sure that the new scsi controller was physical on both nodes and that both servers could see the drives. however when i boot both servers one gets a file lock and stops booting, when i remove the RDM pointers from the afffected server it then boots normally. When i look at the cluster setting i see the VMWare DRS is not enabled, from reading the best practice doc from vmware i think this should be enabled to setup an affinity rule etc..

What i would like to know is if i turn on VMWare DRS now will it affect any of the other virtual machines listed in my ESX host of which there are about 40. i.e cause them to crash or affect other existing clusters that were setup before me.

Question by:Alan OBrien
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LVL 123

Assisted Solution

by:Andrew Hancock (VMware vExpert / EE MVE^2)
Andrew Hancock (VMware vExpert / EE MVE^2) earned 2000 total points
ID: 39621459
As for your initial request, let me get this correct...

you wanted to setup two VMs to Access a single RDM LUN - ?

This is NOT possible. Two VMs cannot access a iSCSI drive concurrently, e.g at the same time.

I think you need to go back to the person, that requested this. VMware DRS will not solve this.

BTW, what you are observing is to be expected.

If you want to connect two VMs to the same RDM, you will need to use Failover Clustering and/or Clustered Shared Volumes.

What are you trying to do?

When you enable DRS, you can select Manual or Automatic, when setting to Manual, it will do nothing until you Click RUN DRS, and it will then vMotion VMs between hosts, and try to balance hosts.

It will not cause virtual machines, to crash, but it may relocate Virtual Machines amongst hosts to balance, CPU and Memory between hosts, using vMotion.

I would test a vMotion (Live Migrate) to check this is working before enabling VMware DRS.

But it will not cause VMs to crash!

Author Comment

by:Alan OBrien
ID: 39621635
ok grand, what am i trying to do.

here is what i have.

2 virtual servers running windows 2008 R2 - both on separate hosts, both run normally
6 RDM's drives

i want to setup a cluster between the 2 servers with the RDM's holding the data so when when one server fails the data automatically rolls over to the other server. i dont see an option to set up an affinity rule so not sure how to seperate the 2 servers from seeing the rdm's at the same time.
LVL 123
ID: 39621659
Okay, Windows 2008 R2 and Microsoft Failover Clustering, that's workable, but has nothing to do with VMware DRS, and setting up.

Also make sure your RDM drives are DATA drivers, and NOT OS drives.

So install each OS on a virtual machine disk, with additional RDM data disks, ensure that your SAN is compatible, and that mapping has been completed for WWNN or iSCSI IQNs.

The easiest way to do this, is to present the RDMs to both servers, and follow the documents here, and ensure your SAN is compatible with Failover Clustering which you must install. and then run the Verification Wizard.

Setup for Failover Clustering and Microsoft Cluster Service - ESXi 5.0/vCenter Server 5.0

other than, it's common sense, that you would want to keep apart the two VMs on different hosts!

Affinity Rules are created

Edit the Cluster > Select vSphere DRS > Affinity Rules.
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Author Comment

by:Alan OBrien
ID: 39621777
"Edit the Cluster > Select vSphere DRS > Affinity Rules."

This option is not listed anywhere when i edit the settings.
see attached pic
LVL 123
ID: 39621809
That's because VMware DRS is not enabled, you need to put a tick in the box, to enable it on that screen!

Accepted Solution

Alan OBrien earned 0 total points
ID: 39629763
Didn't need to turn on DRS in the end. I went back to the start, deleted all the RDM's off each server (after i powered them down) and re-added them again making sure that the SCSI controller for the RDM's was set to physical and that all the drives were on the right SCSI bus. This time they took for some reason and both servers were able to power up and see the drives. After this i was able to build the cluster successfully..

Author Comment

by:Alan OBrien
ID: 39629769
I've requested that this question be closed as follows:

Accepted answer: 0 points for aobrien32's comment #a39629763
Assisted answer: 200 points for hanccocka's comment #a39621659

for the following reason:

Was able to solve the issue as described above
LVL 123
ID: 39629770
I'm objecting to this closure based on the information give in the overall post.

As pointed out in my first post, VMware DRS is not required to setup Fail over Clustering, and resolve your issue, this is mis-configuration.

BUT, you will need to use VMware DRS, and Affinity Rules to keep the servers on separate hosts!

Author Comment

by:Alan OBrien
ID: 39630007
no i wont, i have set it up as described and it is working perfectly. In the end i didn't need the affinity rule so i didn't need to enable DRS
LVL 123
ID: 39630065
Are both VMs on different Hosts or the same host?

If the host fails which is hosting both VMs, the cluster will fail, because both VMs are down.

So you will need to ensure, that both VMs are hosted on separate servers, to maintain service and keep the Cluster up.

Author Comment

by:Alan OBrien
ID: 39630167
yea each server is on a different host
LVL 123
ID: 39630209
So if you have manually ensure, VMs on different hosts to maintain service, which is what VMware DRS Affinity Rules can do for you, if you want to load balance your cluster with VMware DRS.

Your question, went off topic I bit from:-

"What i would like to know is if i turn on VMWare DRS now will it affect any of the other virtual machines listed in my ESX host of which there are about 40. i.e cause them to crash or affect other existing clusters that were setup before me.".

which has been answered in http:#a39621459, the rest of the posts, are the recommended scenario.

Author Comment

by:Alan OBrien
ID: 39630552
yea i apologize for that, when i went back to the client they told me that DRS could not be turned on (something they didn't mention in the first place) as they had their vm's spread over 2 data centers and didn't want DRS to start load balancing them so in the end i had to use the solution that i ended up with . If i could have used DRS then the solution you provided would have been correct but as it was i couldn't in the end which is why i gave you partial points, would have been full points if i used your solution but i didn't but i do appreciate the help.
LVL 123
ID: 39665398
Accept  http:#a39621459

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