SnapMirror SnapVault and Tape-backup

[mheimberg]

Dear all

We are implementing a combined SnapMirror / SnapVault - solution, meaning: the datasets (LUNs for MS SQL and Exchange, NFS volumes for ESX Datastores) are mirrored for DR to an identical FAS and are backed-up by SnapVault to a FAS with SATA drives.

Unfortunately there is still the requirement for tape-backups. Now we are not sure from where we should draw the tape-backup:

- when connecting the tape-backup-software to the SnapMirror-destination we could use a generic-naming in SnapManager, so we would be able to automatically save the last __recent-snapshot to tape by NDMP. But with this approach we could not use Protection Manager, because PM enforces (together with backup-policy) a unique-naming of snapshots

- when connecting the tape-backup-software to the SnapVault-destinations we could also automatically save the most recent snapshot when doing it without Protection Manager: just snapvault snap sched <volume> daily 15@- and some little scripting will give a snapshot daily.0 based on the last recent snapshot on the source.

But again with PM we do not have generic-naming and here too we need NDMP plugins for the backup-software.

But as far as I understood SnapVault, the content of the Qtree after the last replication should be the same as in the snapshot on the source, that is: an application consistent state (of course snaps on the source are created by SnapManagers!). So it should be possible just to connect to the file system on the SnapVault-destination-FAS and copy the data out. Or am I wrong?

What would others suggest? Oppinions?

Regards

Markus

[sheastewart]

Hi,

Your SnapMirror and SnapVault targets are in read-only mode (qtrees or volumes). Only SnapMirror can become read-write, and first you must break the relationship...so in essence it doesn't matter whether you backup from the SnapMirror or SnapVault destination - the data will be the same as the source. NDMP is still my preferred method for backing up this data (to tape) for simplicity and performance, however, this is option needs to be evaluated at the business level as well.

Also keep in mind that Protection Manager does not replace your SnapManager products...In your situation I suspect you may use PM it to monitor the snapmirror lag times and update the SnapVault target. SME and SMVI are still required to perform (control) your backup operations and update mirrors on their respective applications.

Regards,

Shea

[mheimberg]

Hi Shea

Thanks for your input.

In your situation I suspect you may use PM it to monitor the snapmirror lag times and update the SnapVault target.

From other posts this really seems to be the way.

IMHO this clearly shows that the whole DFM/PM/SM-thing is not matured, not even Version 1.0. I mean: do the SnapVault with PM, but you must use PM and SM to get the integration done, but SnapMirror is still done the old way, not to mention all the bugs DFM/PM shows....

I tend to kick away Protection Manager and do it the old way with self-made scripts and look again at it in a year or so.

Regards

Markus

[rgraves2572]

We have a similar setup and we backup to tape using the SnapVault volumes. We backup via NDMP using Netbackup.

The problem with backing up using the SnapMirror destination is it makes the volume busy preventing any updates during the backup. NDMP backups also generate a high load on the filer and Aggregate.

If SME handles the update of your SnapMirror destentations then SnapVAult will be consistent. However, like everything related to backups you should test the recoverability of your backups on a regular basis to validate this.

-Robert

[BrendonHiggins]

Happy New Year

We have 3 site and snapmirror between the 2 data centres.  The 3rd site is for backup (snapvault) and it uses the other 2 sites at its source.  We have had problems with this and now just take the snapvaults from the snapmirror destination on the 2nd site.  We then use CommVault to copy the snapvaults onto tape.  This works very well for use.

Hope it helps

Bren

[mheimberg]

Hi Bren

We have had problems with this and now just take the snapvaults from the snapmirror destination on the 2nd site.

Could you explain a bit more what problems you encountered?

I also have already done implementations of the type "Prod -> SnapMirror -> SnapVault", and it worked perfectly.

But now I am facing requests where we need to Mirror *and* Vault the Prod at the same time (Protection Manager has a policy for that: Mirror and Back-up).

Regards

Markus

[BrendonHiggins]

The issue is from when we move the production service between the data centres and then back again. The filers do not like the resulting layer of snapshots which were created on the different filers.

The issue can be managed however by removing older snapshots or running the services in the sites for longer than the snapshot retention period.

Bren

[mheimberg]

Got it - interesting issue....

Regards

[radek_kubka]

Hi Robert,

The problem with backing up using the SnapMirror destination is it makes the volume busy preventing any updates during the backup.

Are you saying that SnapMirror relationship cannot be updated whilst NDMP copy of the destination takes place? I would describe this as a serious inconvenience (to say the least).

Regards,

Radek

[rgraves2572]

From my experience this is the case.

That is why performing an NDMP backup on the SnapVault volume has less impact. SnapVault backups are generally faster then NDMP since they only backup incremental changes. Whereas NDMP are generally level 0 backups of the active file system and when tape is involved speed is limited by network and tape speed.

-Robert

[alapati]

Hi,

This should not be the case when backing up with ndmp. SnapMirror updates should continue as long as the Snapshot copy that is being backed up is not deleted on the source.

Srinath