VCS with GCO\Windows2012\VMware 5.1\IBM SVC SAN based mirroring

[ianbd]

We are looking at potentially using VCS for a cross site DR project and have been told by a solution provider that we can use the GCO option in VCS to allow us to have Windows 2012, running on VMware, and using IBM SVC SAN based mirroring. They have not been very clear how it would actually work, and I cannot discern from the VCS 6.1 docs how it would be possible.

The constraints we are working with is that we must use the native volume managers, file systems, and IBM SVC SAN based replication. I can understand how it might work if RDMs are used for the VMs, but they are saying that we can used VMDKs inside VMFS data stores and still achieve our goals.

Can anyone verify this is true, and if it is, explain how it is achieved? I understand how it work with local clustering using the NativeDisks and VMwareDisks agents, but it isn't clear how it works under GCO. The issue I see with it is that there does not appear to be anything that manipulating the VMFS datastores or the LUNs they are made up from. I would really appreciate it if someone could explain exactly what agents are necessary and how they tie into VMware to ensure than the SAN replicated LUNs\VMFS data stores are not mounted\accessed at the remote site.

Thank you,

Ian.

[mikebounds · Accepted solution]

You would need the SVC agent https://sort.symantec.com/agents/detail/915.

I have used this with Windows VCS on phyical servers and so this would work fine with RDM, but don't see how it can work with vmdk.

Whether it works with vmdk is more of a question for IBM as the VCS agent uses SSH to communicate with the IBM SVC so has attribute:

GroupName

Name of the replication relationship or consistency group that is managed by the agent.

So normally the GroupName would be a consistency group containing the LUNs that are replicated.  As the consistency group is an object on the array I can't see how it could be vmdk aware so I think you would have to use RDMs  - if your Solution Provider reckons it can use vmdks, then ask how as this is not a question about VCS - this is a question about "can IBM SVC replicate vmdks and I dont see how it can.

VCS/GCO just automates a set of commands when it fails over, so if there is a manual way to fail over a vmdk replicated with IBM SVC then you can probably do with VCS, but if you can't do manually, then you can't do in VCS/GCO either.

This would work with Symantec VVR as this replicates at the host level so can use vmdk (or you can use Vxvm mirroing if sites are close together - i.e less than 50/80km)

Mike

[mikebounds · Accepted solution]

Just to add, if you had a LUN which contained exclusively the vmdk's for the nodes you are clustering, you might be able to get it to work with some custom scripting to attach and detach LUNs to VMWare, but even if this worked, I don't see the point as if you have a LUN exclusivly for your cluster, then much easy to just present it as RDM than put vmdks on it and try and fudge a solution.

Mike

[ianbd]

Thank you very much for your response.  The Symantec rep on the account came back today and confirmed that we would have to use RDMs for a VCS\Windows\VMware\SAN replication solution stack.  This does change things for us as one of the larger benefits we were originally "sold" on was that moving to VCS would allow us to eliminate the need for RDMs in our VMware environment.

Ian.

[Khalid-DXB]

IAN,

with SVC you can use IBM SVC storage base replication, and we have a Agent for SVC to control the storage replication, thorugh which the Storage is accessible only one site at a time.

You need to create consistency group in SVC and add these luns, I am not sure whether you can add VMDK or datastore, But I am using RDM Disks which is running successfully with GCO

Khalid