3Par 7400 Virtual Copy questions

[Mark Jeffers]

I am looking to find out if the virtual copy feature in our 3Par 7400 storage system, will help me out with a current situation. I have never used the virtual copy feature, and the last training we got was over 5 years ago. 8-)

I have a extremely large LUN (12 TB) presented to a Windows Storage Server 2008 R2 that contains multiple departmental data for our company. It is running low on space and we are going to expand the LUN to provide additional space. Before I attempt to expand this LUN I want to have a hot spare of the data ready to go in the event something happens to the drive during the expansion. I have the data protected on our enterprise backup system, but a restore of the data is going to take a few days.

So I was looking into the virtual copy feature, we are licensed for, and think it will provide me with the hot copy in minutes, instead of days, and if something goes wrong with the drive expansion, I can recover it quicker.

A couple of questions come to mind about this. If I create a virtual copy of a vvol, and then add additional space to that base vvol, should I redo the virtual copy? Or does it matter?

If I have to promote the virtual copy back to the base, do I have to unexport it from the host first, then promote the virtual copy to the base, then re-export it back to the host?

If my host is using a DFS namespace for this drive, will this cause issues with the DFS namespace if it does have to be  unexported and re-exported.

I appreciate any help you folks might be able to give me!

Thanks!

[Sheldon Smith · Accepted solution]

You should have no problem increasing the size of the virtual volume. Once the VV is expanded, in Windows' Disk Management, make it expand the existing partition.

For what you want, you do not need to redo the virtual copy after you expand the base VV. I don't know why you would want to keep the virtual copy once you are done expanding the base volume. On the other hand, if you are looking at using virtual copies to provide quick backups to the volume, then you would want to (periodically) make another virtual copy. I would strongly recommend setting an Expiration time on any virtual copies whose creation you schedule.

If you need to promote the virtual copy, at the very least you would need to unmount the base volume before and during the promote. Cleanest would be to unexport the base as well. Once the promote is complete, export the base and (re)mount the file system.

As far as DFS, no idea.

Take a look at the (new) technical paper, :"HPE 3PAR Virtual Copy: Snapshots and copy data management", #4AA6-4486ENW

Note: While I work for Hewlett Packard Enterprise, all of my comments (whether noted or not), are my own and are not any official representation of the company.
----------
If my post was useful, click on my KUDOS! thumb below!

[Mark Jeffers]

Sheldon,

Thank you for your time.

I understand the process to expand the drive on the Windows server. I was just really hopeful that the virtual copy was an answer to getting this done quickly, and safely.

From what I see in your answer is it does give me the backup copy that I would need, so that in the event that the expansion goes wrong, that I could recover pretty quickly.

I only plan to keep the virtual copy until the expansion is complete, and the volume is stable.

Thank you again for your time and valuable information.

Mark