Re: [Networker] Browse period and very long backup "cycles"

Darren Dunham wrote:

I've been talking to someone that has lots of data that is pretty
static.  It gets added to occasionally, but it doesn't change or get
deleted.  They don't want to be doing lots and lots of fulls, backing up
the same data over and over again.  He basically wants to archive all
the data to tape once (very little money for tapes, only one tape
drive), but leave it on the filesystem.

I've never run a system like this, but I'm wondering if anyone has tried
to do this with something like a yearly full, with daily incrementals on
a big filesystem.  That way all new data would be backed up, but only
once a year.


Darren,

I would be very jumpy about a config like this. Firstly I wouldn't want
to rely a full with a couple of hundred incrementals. If the worst
should happen and the whole filesystem needed recovering you would have
a nightmare. It would take weeks to read through all the incremental
tapes, and if one tape was missing or damaged you might not be able to
recover it at all. There are other issues too, if perhaps some of the
data arrived on the filesystem with an older date (e.g. from a tar
archive or zip file) it would never get backed up by the incremental.

If it was me I would prefer to do a full backup a little more
frequently, then recycle the older fulls, keeping maybe two or more
fulls at any time.

You might consider using differentials rather than incrementals, then
you could periodically make a decision to run another full when the
daily diffs have grown to a pre-determined size. You could of course
recycle your older diffs without affecting the recovery position.

You might consider using save set consolidation, although I don't know
how well that works. Last time I tried it (some years ago) I would have
classified it as "a bit flaky".


If I set the browse period on this system to something short (say a
few weeks), and I've only got one "cycle" on tape, I'm not certain
what Networker will do.  I imagine it will either..

1. Allow the last cycle to be browsed (keeping a year's worth of file
   indexing)
2. Allow only data saved since the browse period to be browsed
3. Once the initial full is past the browse period, none of the
   filesystem can be browsed.


I think if you are still running regular backups of the filesystem it
will do option 1 - since there are browsable incrementals that depend on
the full. If your latest incremental was older than the browse period I
think it would do option 3 - since all backups would be expired.


Any comments on this?  Is this a stupid idea for some reason I'm not
thinking of?  Right now they're doing the equivalent of this, but it's
with scripts that I'm afraid are fragile.


I expect NetWorker can do it better than fragile scripts. However lots
of incrementals is also very fragile.

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