Re: Verbatim 1TB external HDD
I recommend making it an LVM physical volume and creating a volume group on
top of it. Create a logical volume the exact size of the volume you are
backing up, then use dd to copy it for the first time (boot from a CD, if
necessary, so the source volume isn't mounted). Then create an LVM snapshot.
For each backup cycle (in a script called from cron), mount it and use
rsync to only change what needs changing, then unmount it and create an LVM
snapshot. Create the snapshots with names that include the date. To avoid
running out of space, you'll probably want to cull older snapshots from
time to time. For example, you might back up nightly, but you only want to
keep the last three days, the first of the month for a year, and the first
of the year from the previous year. You can automate this in the backup
script as well.
You should also create a script that will mount the available backups
(i.e. LVM snapshots) readonly in well-named directories (i.e. including the
backup date), and another to unmount them all.
I did something like that for a while, but the mount time to recognize all of the LVM internal pointers for
the snapshots was extreme (1/2 hour!). Better to use rsync with the --link-dest= option as in