Networker

Re: [Networker] NetWorker oddity - is it me or just the way it works?

2008-10-08 16:31:44
Subject: Re: [Networker] NetWorker oddity - is it me or just the way it works?
From: George Sinclair <George.Sinclair AT NOAA DOT GOV>
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Date: Wed, 8 Oct 2008 16:27:45 -0400
A Darren Dunham wrote:
On Wed, Oct 08, 2008 at 11:14:56AM -0400, George Sinclair wrote:
Well, it certainly does see any newly created files, or directory names or modified files, but my observation is that it ignores files whose file status times are not newer, even if they've been moved. When a file's mod time changes, so does its file status time, but not necessarily vice versa. Now obviously, moving these to another server, or another file system on the same server, would affect those times, however, since that's a copy and not an actual (atomic) move. Ditto for recovered data (tar, unzip, NW recover, whatever ...) as the file status times will be the time that the file was written to disk even though its mod time may be older (original).

Right.  The only way around this is for the client to have more
information than just the timestamp of the last backup (or last relevant
backup) and the timestamp(s) of the file.

Without the client seeing the whole index, it can't know that there's
any reason to transmit the data about the files present back to the
server.


Darren, that's a good point, albeit and obvious one that I hadn't considered. Maybe I thought that the server could somehow relay this information to the clients, or that they could peer into that index remotely? I guess if that was the case then backups would take considerably longer, and/or the information (meta-data) would have to be stored on the clients for a certain period of time, making the whole operation far more complex and potentially precarious. Either way, it sounds like the way it *actually* works expedites the backup process or at least the amount of time it takes it to figure out what to back up by not having to do all that homework and just keeping things simple. Otherwise, we'd be waiting a lot longer for backups to complete [sigh].

George

--
George Sinclair
NOAA/NESDIS/National Oceanographic Data Center
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