SudhirH
Contributor
Contributor

How to replicate RDM disks configured in virtual compatibility mode?

When a RDM is replicated to a DR site, the wizard asks for the Target data store only. How to replicated the RDM to a RDM device on the target side?

When I tried to confiure the above it created a VMDK file on the target datastore.

Any links or documentation would be helpful.

TIA,

Sudhir

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7 Replies
Burak201110141
Enthusiast
Enthusiast

Hello
Rdm cannot replicate in to rdm device...

Rdm devices can add in to virtual machines actually so RDM disks ( virtual mode ) depend a pointer and it can visible vmfs volumes...

This isn't problem...

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SudhirH
Contributor
Contributor

If I cannot replicate a RDM to RDM at the target site then it is a problem..right?

VMware has not mentioned such a limitation in their document.

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mvalkanov
VMware Employee
VMware Employee

Hi,

vSphere Replication can not automatically create the .vmdk mapped to a RDM at the target site and that is why it defaults to a -flat.vmdk file.

You need to manually prepare the RDM at the target site and create .vmdk for it. It might be easiest to create a blank VM, associate it with the RDM device, unregister the VM from vCenter inventory, but leave the .vmdk at the target datastore. Once the .vmdk is available at the target site, you can select it as initial seed when configuring the replication.

The initial content of prepared the RDM at the target does not really matter. VR will compute checksum on all disk blocks and transfer the different ones during the initial full-sync.


Regards,

Martin

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SudhirH
Contributor
Contributor

Hi Martin,

I tried your suggestion and this is what i get

pastedImage_0.png

Regards,

Sudhir

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aatanasov
VMware Employee
VMware Employee

Hi,

To be able to troubleshoot this problem can you please answer the following questions:

What is the target datastore type (DS1_649_650)? Is it shared (iScsi, NFS) or local disk? How many hosts have access to this datastore? Have you ever seen this datastore being inaccessible? Are you able to browse this datastore using the following URL:

https://$VC-HOSTNAME/folder (Find more info on how to use Datastore browser at http://blogs.vmware.com/vsphere/2010/01/scripting-datastore-access.html)

How many times you tried configure replication and get this same error (on the screenshot)?

Regards,

Atanas

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SudhirH
Contributor
Contributor

What is the target datastore type (DS1_649_650)? Is it shared (iScsi, NFS) or local disk?

Ans: It is created from SAN FC Luns.

How many hosts have access to this datastore?

Ans:  Two ESX hosts have access to the Datastore. These two esx hosts are part of a cluster.

Have you ever seen this datastore being inaccessible?

Ans: NO

Are you able to browse this datastore using the following URL:https://$VC-HOSTNAME/folder

Ans: Yes

How many times you tried configure replication and get this same error (on the screenshot)?

Ans: Each time I tried configuring.

Can you provide steps for replicating RDM disks to a RDM disk on the DR site using Vsphere replication?

I even tired modifying the vmdk UUID to match the source VMDK.

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aatanasov
VMware Employee
VMware Employee

My first guess was that there is a temporary problem with the destination datastore (DS1_649_650) but based on your answers you don't have issues browsing the datastore.

The second guess is that maybe you are using RDM type virtual disk which backing is a device connected to only one of both hosts having access to the destination datastore - where the RDM descriptor file is located (that is the file testvm.vmdk). What is the backing of the RDM disk? Is the RDM backing device connected to both hosts in question? Can you power on the testvm with the RDM disk on both hosts?

As for the steps to replicate VM with RDM disks and use another RDM disk as seed you need to ensure the following:

- The RDM disk size must match exactly on both sites;

- The set of hosts connected to the datastore containing the seed RDM descriptor file is exactly the same as the set of hosts connected to the seed RDM backing device.

If this is your case and you are still getting same error then it will be best to open an SR for further investigation. Please, post the SR number in this thread so we can have closer on this at some point.

There is no need to match disk UUIDs, because vSphere Replication does not validates UUIDs when the seed disk is of type RDM.

Another thing to note is once you have the replication configured, you may remove the testvm (the one used to create the seed RDM disk, not the protected one!) from the inventory of the destination VC.

Regards,

Atanas

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