Merge two datacenters (storage migration)

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Hello.

This is RHEV 3.2 environment.

The task is to merge DC1 and DC2 into one DC. I know that supported and documented method is to use export domain.
However I am wondering of other method which could go like this:

  1. Create fc storage pool (SP1) for DC1
  2. Move all VMs to SP1
  3. Shutdown all DC1 hosts.
  4. Destroy DC1
  5. Add DC1 hosts to DC2
  6. Present SP1 luns to DC2 hosts

Would it work? How would RHEV-M behave if it saw luns with the correct lvm structures with data on it ?

Thank you for any suggestions

Marek

MB
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Responses

GS Expert Active Contributor 1269 points
8 May 2014 2:23 PM

Essentially you want to import a storage domain into DC2. You can import ISO domains and export domains. I doubt you can import storage domains. But even if you can, you still have to provision all your old DC1 VMs again and hook the VMs up with the correct disk images.

Granted, if your method works, it might save some disk space. But even if it would work - and I doubt it will - but even if somehow it would work, it is filled with risk. You have no path back if anything goes wrong.

As for saving disk space - well, not really.

Consider the supported export/import method. Which is proven and really does work BTW. Export that first VM from DC2, then import into DC1. Test it. When it tests good, get rid of the virtual disk copy in the export domain and get rid of the DC1 copy of the VM. And now do the next VM.

The total extra space using export/import is 3X one VM. In your proposed method, the total extra space is 2X all DC1 VMs. The supported export/import method wins unless you have one overwhelmingly large VM.

- Greg

MB Active Contributor 270 points
22 May 2014 10:02 AM

Greg, thank you for your reply.

I am going to go using documented and supported way that is using export domain.
My only concern was speed of nfs as it is quite slow comparing to fc. Thus my above question.

I finally manage to tune nfs server serving export domain to perform twice as fast as out of the box. As the speed is acceptable I will go with this solution. Anyhow I have no other choice ;).

Marek

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