Storage vMotion consumes a lot of space on the SAN

[OskarLarsson]

Hello!

I recently started to create individual datastores for my virtual servers. Before I started, several servers were stored in the same datastore/vmfs on our HP P4000 SAN - but now I want to separate them using Storage vMotion.

I use thick provisioning for the virtual harddrives on the wmfs datastores - and thin provisioning on the SAN-level.

The first server I moved did consume 100GB on the datastore/vmfs with 75GB space provisioned on the SAN volume. But when the server was moved the destination volume on the SAN consumed more space on the SAN than the virtual harddrive needs. The consumed space on the destination LUN is now 142GB - and it was empty before the Storage vMotion...

I was expecting that the footprint on the SAN of the moved server would be the same as it was before it was moved (~75GB)...

Does it matter if the server is turned on or shut down? Maybe the footprint gets smaller on a turned down server?

Do anyone have any experience on this?

Thanks in advance!

[Troy_Clavell]

Does it matter if the server is turned on or shut down? Maybe the footprint gets smaller on a turned down server?

Yes, it does matter, when a guest is powered off you will see no swap file.  However, when you power on the guest a swap file (vswp), equal to the amount of installed RAM is created and remains while in a powered on state.

[OskarLarsson]

The swapfile is only 2 GB so it isn't the problem here.

Message was edited by: OskarLarsson

[Troy_Clavell]

you have no other files in the datastore that are not part of the virtual machine file set?  For insance ISO's?  The guest as no snapshots?  Remember the LUN will grow, on the SAN side, as needed, if thin provisioned.  How big is the actual LUN that was thin provisioned?

[OskarLarsson]

The LUN is set to max 200GB when fully provisioned - and now it is 142GB. No other files than the VM's resides on the datastore - and it was empty before the server was moved. No snapshots.

The VM takes 107GB on the datastore - 105GB vmdk and 2GB vswp.

[Troy_Clavell]

...and you are 100% sure this guest in question was not provisioned on the ESX side as well?  If not, I'm unsure why this is happening.

[OskarLarsson]

The guest is fully provisioned on the ESX side, but the datastore is stored thin on the SAN-volume.

[OskarLarsson]

Now I tested once again, with two different powered off virtual servers.

One of them did "over allocate" space on the SAN when it was moved, and one did not allocate more space than before it was moved...