General SRDF questions

Question

So, I'm trying to get some facts straight about SRDF. I'd appreciate any answers to these questions.

1. If my SRDF group is suspended, does it matter what mode it is in? While suspended, is Adaptive Copy treated differently from Async or Sync?

2. When trying to do the initial sync or trying to catch up, which will have less impact on the rest of the activity on the arrays, Adaptive Copy - Write Pending or Adaptive Copy - Disk?

3. Since Timefinder Snapshots are not supported with SRDF/A devices in Async mode, is it possible to take a Snapshot of a Clone of an SRDF/A device?

MikeMac1 · Accepted Answer

1. If my SRDF group is suspended, does it matter what
mode it is in? While suspended, is Adaptive Copy
treated differently from Async or Sync?

With SRDF suspended it does not matter what mode it is in. No data will be transfered from the source to target.

2. When trying to do the initial sync or trying to
catch up, which will have less impact on the rest of
the activity on the arrays, Adaptive Copy - Write
Pending or Adaptive Copy - Disk?

Adaptive Copy Disk

3. Since Timefinder Snapshots are not supported with
SRDF/A devices in Async mode, is it possible to take
a Snapshot of a Clone of an SRDF/A device?

A few quick questions. Are these R1 or R2 devices?

Are you looking at using Clone to get a backup of the SRDF/A device, then use Virtual SNAP to get snap shot of the target device correct?

Message was edited by:
MikeMac

MikeMac1 · Answer

The Symm keeps track of all the tracks that have been updated on the source (and target) while SRDF is suspended, this process is the same no matter what type of SRDF you are using.

I'm in the process of checking with Engineering on question 3.

Trouphaz · Answer

So, for 1, do they all store the track changes in the same way while it is suspended?

For 3, we're currently doing a Clone of our SRDF pairs in order to have a copy of production for our UAT testing. We would like to be able to have multiple copies, but don't want to waste that much disk for Clones. Someone mentioned that you have the limitation where you can't Snap an SRDF pair in async mode, but since the Clone is in the middle we may be able to Snap from that and make multiple copies for testing.

The clones will generally be of R2 devices, but these are dynamic RDF pairs in a VCS Global Cluster, so it is entirely possible that they'll become R1s at some point.

Right now we're only using Clones and it is to make another copy of the database. Snaps would give us the ability to make more copies with minimal storage waste.

Message was edited by: Joe - added more details.
Trouphaz

MikeMac1 · Answer

Can you shoot me an e-mail please, my e-mail address is in my profile.Thank you.

Rich15_ca72de · Answer

Hello,

In VMAX current 5876, we can have a TF Snap of an R2 device in async mode, however it will require that write pacing is enabled. And you can have cascaded TF so that you can go from R2 to clone to TF Snap as well. Keep in mind that we would recommend that you use TF VP Snap instead of std TF/Snap vdevs. Much more efficient in VP devices if thats your situation. .

Symmetrix

General SRDF questions

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