Duplication incrementals from MSDP to Tape

[BoerLowie]

Hi,

I have an SLP that backs up to MSDP and then duplicates to Tape.

When i do Full, it will offcourse duplicate a full to Tape as well.  But when i do Incrementals, i have the feeling it's always duplicating full images to Tape.  Is this correct?

[Marianne]

No idea why you have this 'feeling'.

Show us a backup policy and SLP config that is specified in the policy.

[BoerLowie]

Sure,

i'll post them tomorrow together with a test run.  Full are running at this moment.

Side note that i didn't mention. I'm using the Accelerator feature in the policy.

[Bmitche · Accepted solution]

The same happened to me....accelerator backups will only produce fulls. It's great for your full backups but not for your incrementals. Hopefully this will change soon.

[BoerLowie]

Found the answer in another thread:

https://www-secure.symantec.com/connect/blogs/netbackup-accelerator-vmware-whole-new-world

So incremental Accelerator backup will always be duplicated as Full images to Tape.

Which is a shame because we have to duplicate everything to Tape for offsite vaulting, and this makes Accelerator rather useless for us on most policies...

[Nicolai]

I think not - it a design decision. Accelerated backup cannot be dependent on another storage unit to full-fill a restore request. That why some backup get converted from incremental to full when duplicated.

This is confirmed for VMware at least.

[Marianne]

Do not confuse 'rehydrate' to tape with full image. 

There is no way that duplication of a particular image (e.g. incremental) will use another image (e.g. full) for a duplication.

Please show us evidence of policy and SLP config in your environment.

[BoerLowie]

Here we go.

So i did a VMware Backup of one VM with an SLP configured to backup to MSDP and then duplicate to tape.

The following was run:

- Full backup with Accelerator enabled. (78787)

- Incremental with Accelerator enabled (78790)

- Full backup with Accelerator disabled (78794)

- 2x Incremental with Accelerator disabled (78798 & 78803)

As you can clearly see, only the Incrementals without Accelerator enabled have the same amount of bytes duplicated to tape.

The incremental with Accelerator enabled shows as a full image (looking at the kilobytes column) and also duplicates full to tape.

If this is designed like this, it gives Accelerator a huge penalty when duplication incrementals to tape...  For our environment that's the difference between writing 5 or 20 tapes daily...

[RonCaplinger]

This looks to address what you see as true:

https://www-secure.symantec.com/connect/blogs/netbackup-accelerator-vmware-whole-new-world

"Accelerator VMware backups will support MS SharePoint, MS SQL and Exchange Full schedule only, no Incremental or Differential."

"Similarly to file system Accelerator backup, supported since NBU 7.5, the Accelerator backup for VMware will generate a Full image on the storage server using blocks from previous image (Synthetic backups). Only the blocks that have changed are transferred from client to media server."

Your screen shot looks like the subsequent backups using Accelerator were, indeed, faster.  But It appears that the changed blocks from the incrementals still need the rest of the blocks in the Full backup image in order to generate a new incremental.

Note StefanosM's post:

"BE AWARE THAT THE FOOTPRINT OF THE INCREMENTAL BACKUP IS A FULL BACKUP.

For SQL and exchange systems this is ok as they are always full. And for all of you that do not use tapes accelerator is ok.

BUT if you are duplicating your incremental backups to tape, then VMware accelerator backup is NOT for you."