topic Re: Question on EVA Continuous Access in Disk Enclosures

Question on EVA Continuous Access

Kurz — Wed, 27 Dec 2006 07:44:46 GMT

Can you backup from a mirrored LUN (via Continuous Access) on a 2nd EVA?
How do you see the mirrored LUN?

TIA,

M. Kurz

Re: Question on EVA Continuous Access

Peter Mattei — Thu, 28 Dec 2006 12:14:22 GMT

Yes you can!
There are two ways:

1. Suspend the DR Group; then you can mount the replicated LUN to a server and do backups; after that you unmount ist an you can resume CA replication.

2. Create a Snapclone or Snapshot of the repliacted LUN and backup that copy!

Cheers
Peter

Re: Question on EVA Continuous Access

Kurz — Fri, 29 Dec 2006 03:22:58 GMT

Dear Peter,

thanks for your answer.

I am not sure if your answer implies that it's possible during normal operation.

1) If you're talking about resuming CA, this seems to imply that it needs to be stopped beforehand.

2) sounds better. Is both possible, Snapclone and Snapshot? (I ask just to be sure because it's important.)

It seems logical to me that we would try to keep the backup load off our productive EVA and try to shift it to the mirror EVA. But of course we don't want to interrupt replication, and we don't want to make an extra copy of the replication copy.

thx,

M. Kurz

Re: Question on EVA Continuous Access

Peter Mattei — Fri, 29 Dec 2006 11:38:19 GMT

No, you cannot use the remote copy of CA while it is in copy state!
The consistency of the data could not be guaranteed!

1. When you suspend CA the primary EVA starts logging all writes. The remote copy gets normalized and can be used for backup etc. When you resume CA the accumulated log will be replicated and applied to the secondary EVA. After some time (depending on log size and available bandwidth) CA will be back to normal.

2. Yes, both is possible!

Note: You need to make sure in both cases that your data is in a consistent state before you either suspend or snap! In case of a database this is accomplished by putting it into online backup mode! This will flush all caches (DB, server etc) and make the data on disk consistent.

Cheers
Peter

Re: Question on EVA Continuous Access

Kurz — Wed, 03 Jan 2007 04:51:26 GMT

Thx a lot for your detailed and very helpful answer!

Michaela Kurz