Quibbles – Why can’t you clone or stage incomplete savesets?

NetWorker has an irritating quirk where it doesn’t allow you to clone or stage incomplete savesets. I can understand the rationale behind it – it’s not completely usable data, but that rationale is wrong.

If you don’t think this is the case, all you have to do to test is start a backup, cancel it mid-way through a saveset, then attempt to clone that saveset. Here’s an example:

[root@tara ~]# save -b Big -q -LL /usr
Oct 25 13:07:15 tara logger: NetWorker media: (waiting) Waiting for 1
writable volume(s) to backup pool 'Big' disk(s) or tape(s) on tara.pmdg.lab
<backup running, CTRL-C pressed>
(interrupted), exiting
[root@tara ~]# mminfo -q "volume=BIG995S3"
 volume        client       date      size   level  name
BIG995S3       tara.pmdg.lab 10/25/2009 175 MB manual /usr
[root@tara ~]# mminfo -q "volume=BIG995S3" -avot
 volume        client           date     time         size ssid      fl   lvl name
BIG995S3       tara.pmdg.lab 10/25/2009 01:07:15 PM 175 MB 14922466  ca manual /usr
[root@tara ~]# nsrclone -b Default -S 14922466
5876:nsrclone: skipping aborted save set 14922466
5813:nsrclone: no complete save sets to clone

Now, you may be wondering why I’m hung up on not being able to clone or stage this sort of data. The answer is simple: sometimes the only backup you have is a broken backup. You shouldn’t be punished for this!

Overall, NetWorker has a fairly glowing pedigree in terms of enforced data viability:

• It doesn’t recycle savesets until all dependent savesets are also recyclable;
• It’s damn aggressive at making sure you have current backups of the backup server’s bootstrap information;
• If there’s any index issue it’ll end up forcing a full backup for savesets even if it’s backed them up before;
• It won’t overwrite data on recovery unless you explicitly tell it to;
• It lets you recover from incomplete savesets via scanner/uasm!

and so on.

So, logically, there makes little sense in refusing to clone/stage incomplete savesets.

There may be programmatic reasons why NetWorker doesn’t permit cloning/staging incomplete savesets, but these aren’t sufficient reasons. NetWorker’s pedigree of extreme focus on recoverability remains tarnished by this inability.