Mirroring LUN for sharing purposes

I do not know of any way you can achieve what you are looking for.  You can clone a standard to another standard but that is a point in time type of copy.  You may need a third party piece of software to achieve this dual write capability while keeping both devices available.

I also do not see how you will not corrupt the data.  VMa is going to be sending writes to the luln while VMb is also accessing the same lun; VMb has no idea what VMa is doing so its going to see changes to the lun it does not know about and flag it as corruption.

Depending on how available you need this data you could run a clone session every X number of hours to be able to work on this but again its going to be a point in time copy not real time.

Hi

Are we using cluster software inside VMa and VMb? or

Are data written concurrently from VMa and VMb?

Normally if one of the VMs are writing data, I would recommend adding same LUN as a RDM to both the VM's.

Thank you both for the answer.

Actually, VM_A and VM_B are not active at the same time in the LUN. They are running the same software and the only reason why there are two VMs is to avoid having a Single Point of Failure. This means that VM_B is passive and it does not read or write the storage. It will only do that in case VM_A is destroyed. Due to the fact that VM_B has access to the same LUN, the take over time will be small.

Regarding hemachandra answer, the problem of RDM is that we cannot use vMotion and we need to use it .

Thanks for the help

If only one VM will be active at a given time i dont think you have any problem with your setup. The only doubt I have is how you are going to create the copy of your LUN?

regards,

Saurabh

What software you are running inside virtual machine? Is it MSCS?

What settings is configured in "virtual machine > properties > SCSI controller" ?

Do we have DRS configured?

With VPLEX you can have a LUN on site A and another on site B which are mirrored by the VPLAX appliance. Both sites are writable and any write to either side is replicated to the other side. This wat you can look at you LUN as a single LUN which "lies" over 2 sites.

True RRR but thats also a stretched cluster from what I understand not a two independent server setup accessing the same lun.  Since its an active/active cluster there is a controlling mechanism to know where the most current data is and prevent corruption.

Ah yes, serving both the Clariion/VNX side as well as the enterprise side, I read "mirroring" and I assumed Mirrorview. My bad, I didn't read the question properly. But mentioning VPLEX here is a good thing, yes

zgz_rever wrote: Regarding hemachandra answer, the problem of RDM is that we cannot use vMotion and we need to use it .

Where did you read that ?

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1005241

Oh ok! I got the idea that RDM is not a good option for us because we lose the good features of virtualization so I thought it was vMotion, Fault Tolerance and so on. What we will try is to disable the locking in both VMs, using the multi-write flag. I will keep you updated

Using VPLEX you can see the same LUN from both VMs but you cannot use the same vmdk from both VMs at the same time. You end up with the locking mechanism! VPLEX, as far as I understood, is a solution to communicate storage solutions of different datacenters.