Re: [linux-lvm] Using LVM snapshots for hourly backups

["Greg Freemyer" <greg.freemyer@gmail.com>]

On 10/13/06, Roger Lucas <roger@planbit.co.uk> wrote:
> Hi Nick,
>
> RSYNC is useful for this, but it works at the file level.  If you had, for example, a 1GB e-mail file (e.g. Outlook PST) or a large
> database file, and it was getting small changes every day (e.g. receiving a dozen 10KB e-mails => 120KB of changes), then RSYNC
> would quickly eat up your disk space as each backup taken with RSYNC a complete new copy of the whole 1GB file.
>
> Cascaded LVM snapshots, on the other hand, would allow the just the changes within the files to be kept, dramatically reducing the
> disk usage.
>
> I'm sure that you know this already, but it was worth explicitly stating the difference between RSYCN and LVM snapshots in case
> someone reading the list wasn't as sure.
>
> BR,
>
> Roger

For now, you may want to checkout rdiff-backup.  It uses rsync like
functionality to find deltas in your files and then it only backs up
the deltas.

IIRC, it actually keeps a current copy of your file, plus a series of
deltas that let you get to older versions.

Greg
-- 
Greg Freemyer
The Norcross Group
Forensics for the 21st Century