HPE Storage Users Group

I am trying to use Remote copy solution to replicate VMware Templates. The perfect solution would be to use 3par Remote Copy. I am not able to find in the documentaiton if this is safe to export LUN pair (Remote Copy) on both arrays to different hosts. In remote copy I see that one LUN has assigned attribute in Remote Copy "Writabel LUN" but I am not sure if this is safe to export the backup LUN to a host. Has anyone tried this ?

I do not think the array will let you export a target of RC as writable, it will export, but will be read only. You can write a script that refreshes a snap of that target volume and presents that as writable.

If there's a writable snapshot on the target array then you can present his no problem, if it's only a read only copy, just create a writeable one and present it.

I am assuming you want to do this just the once and not keep it synced and viewable on the second site form vmware.

Thank you for all you replies.

I can tolerate that LUN is writable only on one side. So can you confirm that exporting LUN pair (RC) to different hosts and have primary LUN writable and secondary LUN read-only doable ? This would solve my problem.

As far as snapshots are concerned I am concerned how VMFS will react to snapshot refresh.

I haven't got an array to test this to know for sure so I'm going by memory.

But I don't think you can present a read only lun.

When you try and present the lun from the target, you're going to be creating a writable snapshot and presenting that I think.

So it will work to give you the templates for that moment, but when remote copy updates you won't see the updates, you would need to remove that presented snapshot and create another snapshot of the newly replicated data and present that.

So it would be manual each time.

That's how I understand it without have a play. Hopefully someone should be able to confirm whether I'm right or not.

Davidkn wrote:I haven't got an array to test this to know for sure so I'm going by memory.

But I don't think you can present a read only lun.

When you try and present the lun from the target, you're going to be creating a writable snapshot and presenting that I think.

So it will work to give you the templates for that moment, but when remote copy updates you won't see the updates, you would need to remove that presented snapshot and create another snapshot of the newly replicated data and present that.

So it would be manual each time.

That's how I understand it without have a play. Hopefully someone should be able to confirm whether I'm right or not.

You can present a read only lun. I've experimented with this before.

The problem is that without an operating system that understands that what it's seeing is a read only copy that will only become active on a failover, signaturing and mounting the lun won't work.

Presenting read only luns is really something you'll only do if you're stretching clusters using clx

The best way would be to create a virtual copy, and script the virtual copy being torn down and rebuilt from the ro lun periodically if you need to keep them in sync

Ah ok, so yes, some scripting may be required, although in reality how often will a template change, might aswell just do a manual presentation the odd time it happens?

Davidkn wrote:Ah ok, so yes, some scripting may be required, although in reality how often will a template change, might aswell just do a manual presentation the odd time it happens?

Depends on your use case.

If the template wont change much, and you're ok with blowing out the snap and re creating it every time then go for it