Nsrclone process

[terrywashington]

Is there a benefit to cloning a tape by individual ssid vs. cloning the entire tape? I am asking because we have now run backups to a VTL and dump data to tape via a script that clones the VTL tapes by ssid. Once the data has been dumped to tape we clear the VTL tapes for the next backup by relabeling them via the nsrjb command. I am considering changing the script to clone entire volumes instead of the ssids. I want to make sure that I will still be able to restore data from the cloned tapes.

 

[605]

The only difference would be that the volume clone will clone all save sets which are started on that volume. So the result could be slightly different.

 

[terrywashington]

That's OK. I have actually cloned a couple of entire tapes instead of individual ssids and was able to successfully restore from them. Thanks for the info!

 

[Chapter11]

605 - followup question:

does a clone-by-volume ignore middles and tails then?

 

[terrywashington]

I'm not sure. The command that I use is below. My understanding is that it copies all of the save sets to another tape and spreads it across multiple volumes if needed.

nsrclone -v -b <clone pool> <volume name>

 

[a060463xyz]

If you clone an entire volume nsrclone will only clone complete savesets.
If you clone by ssid nsrclone will clone the whole saveset regardless over how many volumes the saveset is distributed.
In addition a cloning by ssid will demultiplex the savesets thid can result to a better restore performance.
To my opinion saveset clonig is preferrable to volume cloning.

 

[605]

@chapter11

Yes, since a while (AFAIR, back in 7.3), the behavior has been changed:
- In previous versions, a volume clone cloned all save sets which had a reference to that media.
- Since then, a volume clone cloned only the save sets which started on that media.

But correct - as a partial save set would not make sense, NW always copies the whole SS.