Re: [Duplicity-talk] duplicity and deleted files

[Travis H.]

On Thu, Feb 22, 2007 at 11:32:38PM -0700, Steven Willoughby wrote:
> Martin Kaffanke wrote:
> >I'm using duplicity to backup server data to a second hard disk which is
> >built in into the server.

Have you considered just using rsync?

> >And a second Question:  How do we check if my two harddisks work
> >correctly?  Will that be checked automatically somehow or do I also have
> >to run fsck every night (which needs fs to be mountet readonly I think)?

First, let's be precise in terminology here.  The hard drive working
properly is not something that can be tested; that it works improperly
in some specific way is testable, but it is impossible to write a test
for every possible way it could work incorrectly, because that is
infinite.

And a fsck only says that the data structures on the file system are
consistent; that means nothing about the integrity of the data itself,
just the metadata and bookkeeping information.  As far as I know, the
only way to test for "bitrot" (i.e. the data on disk is corrupted) is
to periodically perform checksums on the data, and compare to stored
values.  Strictly what you want is "end-to-end integrity checking",
so that when you read the data it is verified to be intact from when
you wrote it, and this means that nothing in between (the kernel,
the file system, the disk buffering system, the HDD controller, the
drive firmware, the disk media) has failed.  As far as I know the only
system to semi-automate this would be Solaris's ZFS, so you're going
to have to roll your own.

What you really want to do is run smartd and monitor your logs, and
make sure that any failures get brought to your attention ASAP.  Use
swatch if you have to, and test the setup periodically.  If the disk
starts misbehaving, it will be obvious from the logs.
-- 
Good code works.  Great code can't fail. -><-
<URL:http://www.subspacefield.org/~travis/>
For a good time on my UBE blacklist, email address@hidden

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