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dbutch1976
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Vsphere 4.1 / Vsphere 5.0 Split Cluster

Hello,

We are upgrading to vSphere 5 however there is a single critical application which is not supported on vSphere 5.  For this reason I have been asked to investigate the possibility of running a HA/DRS cluster with both vSphere 4.1 and vSphere 5 hosts.

I realize that this configuration would not be ideal, however we don't have enough resources to afford dedidcating a vSphere 4.1 host to run this single VM.

1.  First off, correct me if I'm wrong, but vSphere 4.1 cannot run VMs with VM hardware Version 8?

2.  Secondly, can VMs which are running on vSphere 5 hosts and are running the most recent version of VMtools be vMotioned onto vSphere 4.1 hosts?

3.  Are there any other concerns you guys can think of with running some hosts on vSphere 4.1 and some on vSphere 5 for long periods of time?

Thanks.

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kjb007
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1. - Correct

2. - no, don't update the tools to version 5.0 if you hae esx 4.1 hosts

3. - 4.1 and 5 mix easily enough provided you don't update tools, and you don't use hardware version 8, which you've already noted above.

-KjB

vExpert/VCP/VCAP vmwise.com / @vmwise -KjB

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kjb007
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1. - Correct

2. - no, don't update the tools to version 5.0 if you hae esx 4.1 hosts

3. - 4.1 and 5 mix easily enough provided you don't update tools, and you don't use hardware version 8, which you've already noted above.

-KjB

vExpert/VCP/VCAP vmwise.com / @vmwise -KjB
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kjb007
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It may be easier to just create a 2nd cluster.  You will need to have rules in place to make sure the vm that needs to run on 4 doesn't end up on 5 due to DRS/HA events.

-KjB

vExpert/VCP/VCAP vmwise.com / @vmwise -KjB
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eeg3
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VMware Tools version 5.x is supported on ESX(i) 4.x. The following is a good article in reference to your situation: Mixing ESX/ESXi Versions in an HA/DRS Cluster. The main concern is that hardware version 8 and VMFS-5 are not supported on 4.x.

Blog: http://blog.eeg3.net
dbutch1976
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I agree with you about the 2nd cluster, however we are having some debate as to how to determine which VMs we would keep on the 2nd cluster.  I think that having the 2nd cluster is still the best idea though, because it would give us the opportunity to upgrade VMtools and VM hardware in the vSphere 5 cluster while leaving the vSphere 4.1 alone.

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dbutch1976
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Management's preference is to have all the hosts in a single cluster.  If we do that option and have 2 hosts running vSphere 4.1 with all the others running vSphere 5 how would we ensure that the critical VM is only set to use the other vSphere 4.1 host in the event of an HA failover?

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eeg3
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You can create mandatory DRS rules to enforce it does not go to other hosts.

Blog: http://blog.eeg3.net
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kjb007
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You have to use DRS groups for the vm's and hosts and set a host affinity rule so that the the vm group must run on hosts in host group.  This should keep HA from violating the constraint as well as DRS.

-KjB

vExpert/VCP/VCAP vmwise.com / @vmwise -KjB
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dbutch1976
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That would help us with DRS but do these rules also apply for HA events?

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eeg3
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Mandatory rules apply to HA: http://www.yellow-bricks.com/2011/08/24/mandatory-drs-rules-and-ha/

Blog: http://blog.eeg3.net
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Arno_apx
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Hi,

VMware does not recommand mixing different versions of ESXi in the same cluster.

HA concepts have changed between vSphere 4.0/4.1 and vSphere 5.

In vSphere Availability Guide it's recommanded creating one cluster for each version, especially if you use Storage vMotion because a sVMotion failure during a HA event could corrupt the virtual disk if the VM restarts on a 4.1 host and using snapshots.

dbutch1976
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Hi Arno,

Thanks for your response.  I can see in the guide where it states on page 45 under "Homogeneous Clusters" that different versions are not recommended for fault tolerance, but I'm trying to find a recommendation surrounding HA or DRS.  We don't use Fault Tolerance so I'm not sure that this is applicable to us.

Do you any a link or a reference to a specific Vmware recommendation?

Thanks.

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Arno_apx
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You can read the 2 following guides :

- vsphere 5 availability guide page 33 which relates to interoperability between HA and Storage vMotion

- vSphere 5 High availability deployment best practices  page 5 where VMware says mixed clusters are supported but not recommanded because of differences between the two versions.

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dbutch1976
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Thanks for your reply!

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