Incremental backups and batch mode.
D.Liziero at exeter.ac.uk
Fri Mar 29 08:06:59 EST 2002
Thanks, now I know how rsync backup option works.
But I haven't been so clear about what I would like to do.
>> I would like to have a first snapshot (level 0) that is a complete copy,
>> and then other incremental backups that are just delta files
>> (just the differences from the level 0 snapshot).
>The "normal" utilities for this job would be dump and tar, especially if
>you're dumping to tape. You can also use rsync, but it's somewhat
>indirect if you're dumping to tape! :)
Right, wonderful, but let's consider a big database file, let's say
a 2Gbyte file, that is slightly changed every day of about a 10%
With those tools, the nex level backup consists in checking
the modification time of the files, if the files are changed since last
backup, they are saved again.
So at every backup the whole 2Gbyte file is saved.
If the backup is needed twice a day, in a week 28Gbytes are used, even if
the changed parts are about one tenth.
So I would like to use the rsync algorithm to calculate the differences
(delta files) for the levels n>0 in the same order dump and tar work
but saving much more tape space.
I hope to be a bit clearer now...
More information about the rsync