On Wed, Sep 22, 2010 at 10:07 AM, Jon LaBadie <[email protected]> wrote:
Any thoughts on how desireable you feel be a separate
copy of amanda data would be and other approaches?
This comes up often, and I've never found a solution I'm happy enough
with to make the "official" solution.
Gene's approach is the obvious one, but has a few limitations:
- What do you do if you run out of space on that tape? Start a new
tape? How do you reflect the use of that new tape in the catalog?
- How does recovery from that metadata backup work? There's a
chicken-and-egg problem here, too - you'll need an Amanda config to
run any Amanda tools other than amrestore.
Let's break down "metadata" into its component parts, too:
1. configuration
2. catalog (logdir, tapelist)
3. indexes
4. performance data (curinfo)
5. debug logs
Configuration (1) can be backed up like a normal DLE. The catalog
(2)
should technically be recoverable from a scan of the tapes
themselves,
although the tool to do this is still awaiting a happy hacker to
bring
it to life. Indexes (3) are only required for amrecover, and if your
Amanda server is down, you likely want whole DLEs restored, so you
only need amfetchdump. Performance data (4) will automatically
regenerate itself over subsequent runs, so there's no need to back it
up. Similarly, debug logs (5) can get quite large, and generally
need
not be backed up.
So, to my mind, the only component that needs special handling is the
catalog, and we have a menu of ways to handle that:
- append a copy of the entire catalog to the last tape in each run
(hey, what is the "last tape" now that we have multiple simultaneous
tapers?)
- append a copy of only the catalog for that run to the last tape in
each run
- finally get around to writing 'amrecatalog'
- rsync the entire catalog to another machine nightly
I just stuck that last one in because it was my technique back when I
managed a fleet of Amanda servers. Each would simply rsync its
config
and catalog to the other servers. Since they were all backing up to
shared storage (a SAN), I could do a restore / amfetchdump / recovery
of any dump on any server without trouble. It's a very
non-Amanda-centric solution, but it's *very* effective.
Dustin
