DMotion Migration

[barman1228]

I have heard that DMotion only migrates a VM's first virtual disk. This doesn't seem right or logical and I don't have a lab right now to test this so I am turning to the forums. I looked in the manuals and search existing posts for a clear answer and haven't found one.

I understand that DMotion migrates VMs from VI2 to VI3 and following the migration the VM's hardware and VMtools have to be upgraded. I'm more interested in what the migration actually does or does not do.

So here it is: Does VMotion with Datastore Relocation (DMotion) migrate a VM and ALL its virtual disks or just the first disk? Also, during the migration, does DMotion move only data or the entire VMDK(s)?

Thanks.

[kix1979 · Accepted solution]

I've done a dMotion with multiple VMDK files and it worked just fine. It moves the VMDK files.

[barman1228]

Does it move just the data in the VMDK or the whole file. For example, a VM has a 10GB C drive with 5GB of free space. Is 5GB moved or 10GB?

(I understand that the resulting VMDK on the VMFS3 volume will be 10GB. I'm more concerned with the amount of data being moved.)

Message was edited by:

jwright

[kix1979]

It moves all of the data inside the VMDK. The process creates a new VMDK that is the full size and then copies the data from the old to the new at a block level.

[Mikael_Tissandi]

Hi kix,

So you need to performe the hardware and VMware tools upgrade after doing your dmotion or it appends on the same time? I mean what is the real downtime to plan when using a dmotion process? (for exemple a VM with 10Go disk)

Thanks for your help

Regards

Mikael

[AndrewJarvis]

You need a reboot to do the VMware tools after Dmotion, while the VM is down for the reboot you can do the VM h/w upgrade (vm must be powered off)so tops 5 mins!

[Mikael_Tissandi]

Hi Andrew,

Thanks for your answer...really good for downtime..so could you thus tell me how many time does it take to convert a 250 GB VMFS2 volume to VMFS3?

Thanks in advance

Regards

Mikael

[AndrewJarvis]

Ahh now I have never been brave enough to do a LUN conversion....I've always done the datastore migration thing.....

[DeeJay]

When DMotion is performed it adds some lines to the vmx file which mask off the CPU features to make the VM see the same CPU features on the 3.0.1 host as it did on 2.

Has anyone considered whether the lines should be subsequently moved to reenable the features (perhaps at the same time the hardware is updated and the new VMTools installed)?

[joepje]

You can best think of 60 Gigs in a hour with a DMOTION, and a few minutes when you do an inplace upgrade of the vmfs2 volume

[Mikael_Tissandi]

Thanks for the informations, I can't give you some point...next time perhaps

Regards

Mikael