topic Putting VV's in replication without initial replication of the data in HPE 3PAR StoreServ Storage

Putting VV's in replication without initial replication of the data

Mvhkbc — Tue, 04 Sep 2018 14:16:49 GMT

Hi,

Is it possible to put VV's in a sync-relation without initial replication of the data between them. Just putting primary and secondary in a sync relation.

I used to do this on a IBM DS8K systems.

I created a primary and secondary LUN (3PAR = LUN = VV) seperatly and then did put them in a sync relation with "no copy" param. Result was a LUN replcated to the other site without replication of the data.

Now I see my collegues creating VV's , putting them in a remotecopygroup and this LUN's start replicating every bit from the primary to the secondary site. This (over) loads the replication links without any reasons I would say.

Re: Putting VV's in replication without initial replication of the data

Sheldon Smith — Wed, 05 Sep 2018 00:40:18 GMT

The data is always replicated from the primary to the secondary.

That being said, if you have a new (read: empty) thin volume on the primary, you can either have a similar empty thin volume on the secondary system, or simply tell the secondary system what CPGs to use and it will create a new thin volume on the secondary side.
Whatever is in the primary will be replicated, however you will notice there is Very Little Storage allocated to a new (primary) volume.
Then as stuff ("technical term") is written to the primary, that's replicated as expected.

Re: Putting VV's in replication without initial replication of the data

Mvhkbc — Thu, 06 Sep 2018 07:49:39 GMT

Hi Sheldon,

Correct answer , I can confirm !

I've seen 7 sec to put new, empty VV's in sync. But his was because not other VV's were in the also new created remote copy group .....
When we add new LUN's/VV's to an existing RCG, due to our procedures (3PAR restrictions ?) , one must stop the RCG first .

In that way we supend all other LUN's/VV's in the RCG . After starting the RCG, it took almost 12 minutes to re-sync (action taken during daylights, offive hours).

This re-sync is putting a lot of load on our replication links .

Re: Putting VV's in replication without initial replication of the data

Sheldon Smith — Tue, 29 Jun 2021 11:52:09 GMT

I'm a little surprised.

stoprcopygroup ...
admitrcopyvv -createvv ...
startrcopygroup ...

At any customers I've worked with in the past, this doesn't take much longer to run than it does to type this reply, either using command line or SSMC. A little puzzled that this would take "...almost 12 minutes to re-sync".

Have you contacted HPE 3PAR Support?

How many volumes are in the RCG, and what sort of bandwidth do you have between the remote copy targets? Perhaps the RCG could be split into multiple smaller groups?