VMware Cloning

Posted on 2011-02-24
Medium Priority
Last Modified: 2013-11-05
In a nushell - SAN storage to which VMware ESXi 4.1 VM is connected is having issues. SAN vendor has sent in a replacement unit. I need to shift the datastore AND the virtual disks on the 1st SAN to the 2nd SAN. The virtual disks are connected to the VM via VMWare RDM.

What would be the most efficient way to transfer both the Datastore and the data in the virtual disks attached to VM to the new SAN device?

So far...I have created virtual disks on the new SAN device to match the old SAN, My VM host sees all the virtual disks on both SAN's. I have created the new datastore on the new SAN and I can point to the new datastore in the cloning process.

The Problem -  I am failing to see if there is an option to point the virtual data disks (connected via RDM) to the virtual disks on the new virtual disks on the new SAN.

During the cloning process when I select the datastore is obviously give the warning "Insufficient disk space on datastore" since in the advance tab it is considering the total of the datastore and the data on the attached RDM virtual data disks.

My SAN vendor tech support tells me that this is possible with VMware cloning process, but I am failing to make it happen in my test environment.

If this is indeed possible, I am sure one of the VMware guru here would know. I am presently scratching my head .....

Any help would be greatly appreciated!
Question by:EverardSingh
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LVL 123
ID: 34974754
Can the SAN vendor, not complete the work for you? (they usually do, to ensure you continuous service).

What's the SAN?

Author Comment

ID: 34974845
The SAN device is miSAN by Cybernetics.

I am thinking also that this should be done by the vendor. However, I am getting lots of instructions on how and what to do and not any hands on  help.  I just couldn't explain to them what I wrote here. They were suggesting I needed to get support from VMware,

In frustration I though I post the question here and get a better and or quicker answer.
LVL 123
ID: 34974926
That's very poor, does the current unit have a hardware fault?

Some SANs, you can remove the disks, and insert into a new shelf, and it will recognise the aggreates, volumes, and LUNs, already configured.

As they are the Vendor, they will have experience of this VMware will not provide you with support on how to setup your SAN, they will have no knowledge of a miSAN by Cybernetics!

This is all you are expecting to do, and you should ask them, can you remove all the disks from the current shelf, and insert into the new shelf, and will it recognise the current configuration and retain the data.

All you then have to do is re-present the storage to ESX server.

Do you have any backup products you can do a backup and restore?
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LVL 123
ID: 34975071
Have you got vMotion or Storage vMotion to MIgrate the Virtual Machine to new datastore on new SAN?

LVL 28

Accepted Solution

bgoering earned 2000 total points
ID: 34975499
I think pretty much any kind of cloneing or converting option will likely accept the rdm as input, but the output will be a vmdk. This is probably OK if you have datastores large enough to hold the vmdk, but probably not what you want.

Like hanccocka I would expect the SAN vendor to be able to migrate the data from one SAN to another. Most of them do that all the time if they offer any kind of installation support - it is in there best interests to be able to migrate you off of their competitor's solution and onto theirs.

I see a couple of possibilities here if you can't get support from your vendor.
(1) use clone/converter to clone rdm to vmdk
(2) use a replication product such as Veeam to replicate the data
(3) If you can afford the downtime and reach  both SAN devices from a vm, you could assign the rdm, and a new rdm of the same block count to a linux vm and use dd to copy the data

Good Luck

Author Comment

ID: 34976414

Thanks for the reply.

The problem is with the disks something to do with the snapshot, hence the vendor has replaced the SAN device with all new disks. So, no taking the old disks and sticking them into the new SAN.

I have VMware Essentials - hence, no vMotiion or Storage vMotion.


Author Comment

ID: 34976529

Thanks for the help.

I would not want to store the data within the datastore. There are 5 virtual disks with large amount of data.

your option 3 sounds interesting. I could detach the RDM drive from the existing VM - use the cloning to move the datastore to the new SAN - boot the VM from the new datastore  - attach both SAN's to the VM - attach all virtual disks using RDM - and copy the data from old SAN to the new SAN.

Can you please expound on "use dd to copy the data" I am on windows server 2008 R2

I am still working with the vendor  - i will post the results if what they are talking about has any merit. As you and hanccocka mentioned - I was really hoping for them to session in and do exactly what they are talking about.

I would say in their favor that even though it took some time and effort, they did replace the unit.
LVL 28

Expert Comment

ID: 34976978
dd is a unix/linux utility - stands for disk dump. It will do a binary copy of one disk to another. Because it runs from within the OS it doesn't care if the disk it sees is a vmdk or a rdm.

There is a Windows version (WinDD) available from http://windd.sourceforge.net/ that is supposed to be a port of the dd for unix, but I haven't personally tried it. If it was me I would probably just spin up a quick linux virtual machine to do the copy.


Author Comment

ID: 34999914

Ended up disconnecting all the RDM drives from the VM, then cloning the VM with its datastore to the new SAN device, then used the vendors utility called "Virtual disk copy" to copy all the virtual disk from old SAN to the new SAN (connected via ethernet cable), and then attached the virtual disks on the new SAN via REM to the VM. it worked!

Thanks for all the help!

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