Re: [Networker] NetWorker oddity - is it me or just the way it works?
2008-10-08 12:05:17
I just checked. Apparently, the documented limitation is no longer in
the release notes, but included in the Admin Guide for 7.4.1 on page
622 in the Troubleshooting section "Renamed directories and
incremental backups".
This behavior has existed since at least NetWorker 5.x and it did
get us! I complained, but the best response I got from Legato was it
has been documented as a limitation in (I believe) the release notes
of all further releases of NetWorker. I guess EMC/Legato thinks
users that create millions of randomly named files by running their
codes should be able to remember the old pathnames to all those
entries ...
This isn't really a question but more of an observation, really. I
guess I'd just like to hear what others have to say on this matter.
I'm not suggesting that this is news to anyone, but I really hadn't
ever thought
about this before until I did some testing recently. I think this
is present in all NW versions, and it's simply the nature of the
beast, good or bad. No biggie, really, just want to make sure that
I'm not misunderstanding something.
OBSERVATION
By default, when NetWorker runs incrementals, it will back up any
file whose file status time has changed or is newer than the last
time incrementals ran. I know that that behavior can be changed to
only use mod time, via directives, but otherwise, it's file status
time. And file status time obviously includes more than just mod
time changes like you would expect when a file is modified or newly
created. So, for example, changes to the permissions, ownership,
group, etc. would also force a file status time change (ls -lc),
even if reset to the same value. A more subtle change, however,
would be when moving a file from one location to another, which
also resets the file status time and thus would force a backup.
BUT, let's suppose someone renames a directory. In this case, the
directory's file status time (ls -lc) would change, BUT the
constituent files would still retain their previous times (not just
mod times, but file status times also). As a result, if an
incremental was run, only the pathname to the directory would be
backed up and not the files. I've tested this, and that's the case.
Only a full, numeric or running a manual incremental from the
client, and specifying an older date, will force those files to get
backed up, unless of course you affect a file status time change on
them, e.g. 'chmod -R u+r dirname'. So NW just sees the times and
rather than noticing that the files are now in different locations
(different paths), it just ignores them since they're not newer
than the previous incremental.
PROBLEM
This seems like a potential gotcha because if a user renames a
directory, and then deletes the data, say a week later, and then
you go to recover the directory from that incremental then all
you'd recover would be the directory name. You'd have to go back
further to get the files, but how would you know where to find them
since they were last backed up under a different directory name???
Obviously, you could loop through all the save sets (say over the
last month) for the parent file system using 'nsrinfo -s server -t
nsavetime client' and grep for one of the file names to determine
which directory contained it, or you could just browse around one
day at a time, or some such thing, but it sounds like the only real
answer to this is to expect the user to provide more info to clue
you in as to the fact that the data had previously lived under
another directory?
Does this make any sense? Any comments?
Thanks.
George
--
George Sinclair
NOAA/NESDIS/National Oceanographic Data Center
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Roberta Gold
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--
Roberta Gold
Lawrence Livermore National Laboratory
ICC/HPSD - Security Technologies Group
gold11 AT llnl DOT gov
(925) 422-0167
To sign off this list, send email to listserv AT listserv.temple DOT edu and type
"signoff networker" in the body of the email. Please write to networker-request
AT listserv.temple DOT edu if you have any problems with this list. You can access the
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