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Snapclone on 3Par

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nbhms
Advisor

Snapclone on 3Par

Relatively new to 3Par StoreServ, and one thing I can't find the answer to is if 3Par has a similar feature to what the "snapclone" was on the HP EVA?  On the EVA if you created a snapclone, the target volume was immediately available to present to a new host, and until the clone backfill process was complete, reads were handled in the background with a snap that was taken at the start of the clone operation.

 

I found the 3Par CLI command "createvvcopy -online" which states that "the destination can be immediately exported", but when I create clones using this CLI command they are not available for export any sooner than a normal clone, they just skip the snap creation for resync and do the "promote" step for you.

 

For the most part a clone with a resync will do the job for us, but we have a few scenarios where we really need the functionality that we had with the HP EVA "snapclone".  Am I missing something obvious or is this feature just not in the 3Par?

 

Thanks

 

 

6 REPLIES
Zsal
Valued Contributor

Re: Snapclone on 3Par

HP 3PAR StoreServ does not have the similar Snapclone feature as in EVA. However, you can use Physical Copy feature on the 3PAR.

 

A physical copy is a full copy of a volume. A physical copy duplicates all the data from one original base volume to another volume called the destination volume. Any changes to either volume causes them to lose synchronization with each other, which is corrected by resynchronizing the two volumes.

 

A physical copy can only be created from a parent volume with enough free space to accommodate writes to that volume during the physical copy operation. Physical copies can be online physical copies or offline physical copies. For online physical copies, the destination volume is automatically created and can be exported immediately. Offline physical copies require a destination volume that must have a user space size at least as large as the user space of the base volume being copied, and cannot be exported.

 

Refer to the HP 3PAR Command Line Interface Administrator’s Manual for more information on physical copy & its commands from page 101 onwards:

 

http://h20565.www2.hp.com/portal/site/hpsc/template.BINARYPORTLET/public/kb/docDisplay/resource.process/?spf_p.tpst=kbDocDisplay_ws_BI&spf_p.rid_kbDocDisplay=docDisplayResURL&javax.portlet.begCacheTok=com.vignette.cachetoken&spf_p.rst_kbDocDisplay=wsrp-resourceState%3DdocId%253Demr_na-c03606435%257CdocLocale%253Den_US&javax.portlet.endCacheTok=com.vignette.cachetoken

 

Hope this helps!

Regards

Zsal

Dennis Handly
Acclaimed Contributor

Re: Snapclone on 3Par

>I found the 3PAR CLI command "createvvcopy -online" 

 

What 3PAR OS version are you using?

Would a snapshot work for you?  createsv

nbhms
Advisor

Re: Snapclone on 3Par

My issue is we are doing server migrations, and  I want down-time to be absolutely minimal.  I also want to preserve original data and make roll-back as fast as possible if anything goes wrong during the migration.

 

EVA snapclone was ideal for this.  Shut down source, create snapclone (which is available to present/export in seconds), give cloned disk to new server, application owners do any tweaks required, migration is done assuming testing shows good.

 

If I want to follow that path with the 3Par, I create the clone with resync snap ahead of time, then at migration time shut down source, do the resync, do the promote, do the export to the new box, application owners do any tweaks required, then done.

 

The issue is that on a few very heavy I/O servers, the resync can take quite some time, increasing the outage window.

 

I suppose I could unpresent the original disk, create a snap on the original disk, present original disk to new target, if all good delete the snap, if migration goes bad, unpresent from new, roll back to snap, present back to original server.  I'd just like to keep as few moving parts as possible and keep the roll-back as "pristine" as possible.  Also, some of these servers have 30+ disks - which I can have the CLI commands ready to go ahead of time to minimize the work, but as I said, I like to keep rollback as simple as possible to reduce the chance of error.

 

I'm surprised 3Par doesn't have a similar functionality to the snapclone - it's a very handy feature.

 

Also, I think the wording on the "online clone" for 3par should be changed, as it's missleading.  It needs to say "the clone is immediately available AFTER the full clone operation is done" - basically only saving you the "promote" step at the end.  As it stands, it just says its "immediately avalaible" which made me think it was a snapclone, not an old style clone.

giladzzz
Honored Contributor
Solution

Re: Snapclone on 3Par

Hi

It can be done with "createvvcopy -p vv2 -online " but only using CLI and not GUI also you should export the

physical copy using CLI. try it out in a test enviorment and then in production.

Regards

 

nbhms
Advisor

Re: Snapclone on 3Par

Looks like the piece I was missing was needing to export it from the CLI.  I'd been using the "createvvcopy -online" from the CLI but moving to the GUI to do the export, but the GUI won't allow export while the online copy is running - didn't realize the CLI would allow it while the GUI had it blocked.

 

Thanks for the help.

sivasakthi
Occasional Visitor

Re: Snapclone on 3Par

Is the restriction of cannot export "createvvcopy -online " volume through GUI is on specific version of software?