Unable to migrate VMs with large disks from old non-cluster hosts to hosts in cluster due to DRS Placement Fault error

[sherms]

I'm working on migrating from a vSphere environment with hosts not in clusters to where hosts will be placed in clusters running DRS and HA. Running into an issue that I don't understand when trying to migrate VMs with large VMDKs (1.5 - 2 TB). When I try to migrate the host compute resource for VMs with large disks to the cluster I get a DRS placement fault that there is insufficient space on the datastore that has the files for the VM even though I'm not changing storage just compute. I can migrate the storage to another datastore without issue but can't migrate compute to the cluster. I am able to do the migration if I increase the size of the datastore so their is enough free space on the datastore equal to the size of the VM disk. I can successfully migrate VMs with smaller disks no problem. Looking for some guidance on this issue since I can't find docs that answer my question. Thanks in advance!

[pragg12]

Hi,

Welcome to VMTN. 🙂

I can migrate the storage to another datastore without issue but can't migrate compute to the cluster.

Does the non-clustered ESXi hosts and the clustered ESXi hosts share same hardware product name and CPU vendor ? Is the EVC mode configured in cluster ?

[sherms]

Thanks for the welcome!

Both non-clustered and clustered ESXi hosts are all UCS B200 M3 blades, so yes same CPU / hardware.

[sherms]

Disabling DRS on the cluster allowed me to migrate the VM. I did that as a work around for now but I need to dig a litter deeper into DRS and HA to understand what was happening.

[pragg12]

First thing to check would be if any DRS rules were active for these VMs.

Let us know if you find anything.