Backup Central

Hi,

When using rdiff-backup, is there a way to verify that the backup which
is then stored on the backup server is really 100% correct?

Does rdiff-backup handle this on its own?

I've looked around on the web and in the archives but didn't really find
anything that seemed applicable.

Thanks!

--
Tom Laermans
System Administrator
________________________
Luciad NV
Parijsstraat 74
3000 Leuven
Belgium

Email tom.laermans < at > luciad.com
Web http://www.luciad.com

On Wed, 11 Aug 2004 11:33:58 +0200
Tom Laermans <tom.laermans < at > luciad.com> wrote:

When using rdiff-backup, is there a way to verify that the backup which
is then stored on the backup server is really 100% correct?

Does rdiff-backup handle this on its own?

Kind of. It will flag that the backed up file differs from the original
(if, for example, you back up a changing log file). Is that what you mean?

Keith

--
----------------------------------------------------------------------
Small business computer support: http://www.tiger-computing.co.uk
Linux consultancy: http://www.TheLinuxConsultancy.co.uk
----------------------------------------------------------------------

Keith Edmunds wrote:

When using rdiff-backup, is there a way to verify that the backup which
is then stored on the backup server is really 100% correct?

Does rdiff-backup handle this on its own?

Kind of. It will flag that the backed up file differs from the original
(if, for example, you back up a changing log file). Is that what you mean?


Backups are important, so I need to know if there was a way to check
that the backup is 100% identical to the original, I guess rdiff-backup
does that, as it can check for changed files.

What does rdiff-backup do with changed files? Just leaves the "old" file
backed up and print out a warning?

Thanks.

--
Tom Laermans
System Administrator
________________________
Luciad NV
Parijsstraat 74
3000 Leuven
Belgium

Email tom.laermans < at > luciad.com
Web http://www.luciad.com

On Wed, 11 Aug 2004 14:43:33 +0200
Tom Laermans <tom.laermans < at > luciad.com> wrote:

What does rdiff-backup do with changed files? Just leaves the "old" file
backed up and print out a warning?

Helpful mode: Backs up the file as is, then prints a warning when it
checks.

Unhelpful mode: Try it and see.

A manual but very reliable way to verify backups is:

cd /
find . -type f ! -name "/backups/*" -exec cksum {} \; >
/tmp/cksums_actual

cd /backups
find . -type f -exec cksum {} \; > /var/cksums_rdiff

diff /tmp/cksums_*

Of course any files that change between the two cksums will not match, but
hopefully these would be easily identifiable as having changed (e.g.
they're in /var or /tmp).

Gary

At 05:45 AM 8/11/2004 , you wrote:
On Wed, 11 Aug 2004 11:33:58 +0200
Tom Laermans <tom.laermans < at > luciad.com> wrote:

When using rdiff-backup, is there a way to verify that the backup which
is then stored on the backup server is really 100% correct?

Does rdiff-backup handle this on its own?

Kind of. It will flag that the backed up file differs from the original
(if, for example, you back up a changing log file). Is that what you mean?

Keith

--
Gary Mulder <mailto:gary.mulder < at > infotechfl.com>
Info Tech, Inc.
5700 SW 34th Street, Suite 1235 Phone: (352) 381-4400
Gainesville, FL 32608 Fax: (352) 381-4444

On Wed, 11 Aug 2004 09:05:33 -0400
Gary Mulder <gmulder < at > infotechfl.com> wrote:

A manual but very reliable way to verify backups is:

cd /
find . -type f ! -name "/backups/*" -exec cksum {} \; >
/tmp/cksums_actual

cd /backups
find . -type f -exec cksum {} \; > /var/cksums_rdiff

diff /tmp/cksums_*

That will only work if the backups are to a locally-mounted disk.

Keith

--
----------------------------------------------------------------------
Small business computer support: http://www.tiger-computing.co.uk
Linux consultancy: http://www.TheLinuxConsultancy.co.uk
----------------------------------------------------------------------

You can simply run the find through ssh to the remote machine and redirect
the output to a local file for local comparison.

I'm actually doing this *right now* to verify a 100,000 file backup.

At 09:00 AM 8/11/2004 , you wrote:
On Wed, 11 Aug 2004 08:48:51 -0400
Gary Mulder <gmulder < at > infotechfl.com> wrote:

A manual but very reliable way to verify backups is:

Only if you are backing up to a local (or locally mounted) disk. I do
backups from one machine to another via ssh.

Keith

--
----------------------------------------------------------------------
Small business computer support: http://www.tiger-computing.co.uk
Linux consultancy: http://www.TheLinuxConsultancy.co.uk
----------------------------------------------------------------------

--
Gary Mulder <mailto:gary.mulder < at > infotechfl.com>
Info Tech, Inc.
5700 SW 34th Street, Suite 1235 Phone: (352) 381-4400
Gainesville, FL 32608 Fax: (352) 381-4444

Tom Laermans <tom.laermans < at > luciad.com> writes:
What does rdiff-backup do with changed files? Just leaves the "old"
file backed up and print out a warning?

If a source file has changed, then rdiff-backup will replace the
target file with the current (new) source file, and store a diff that will
enable recovery of the previous version.

If you mess up a target file, rdiff-backup will be unhappy;
I don't remember if it just gripes, aborts the backup run, or what.

Note that rdiff-backup detects changes by checksum and file metadata
like file system, modification time, and so on. I have got a feature
request in the wiki to have a verify mode that does a full comparison.
This should mainly only be needed if you suspect malicious tampering
with the backups or have some kind of filesystem flakiness that makes
you suspect your system's integrity.