[svlug] Back up strategies? - was Data recovery services?
scott at doubleu.com
Mon Feb 27 09:43:49 PST 2006
On 2/26/06, Skip Evans <skip at bigskypenguin.com> wrote:
> What are some backup strategies people use and
> what are some you'd recommend? Big tape drive?
> We'll be rsync'ing the a new server back to this
> one for a while. Is that a popular method?
I've used many strategies over the years, including backup to multiple
classes of tape, backup to read-write optical devices and removable
magnetic devices (before CDs), data-only backup to CD-R, some system
backup to CD-R systems (Mondo comes to mind, provides a bootable
restore process which is cool), backup to DVD-R, and, lastly,
rsnapshot backup to a large hard drive. The latter is the first
system which I've actually _liked_ as opposed to considering it a
necessary evil. It's also the first which I've actually managed to
have working to backup _all_ my systems.
rsnapshot is a system built on rsync (there are a couple other such
systems out there, rsnapshot is just the one I used). At every
backup, it copies the existing backup instance to a new place, then
uses rsync to pull any changes over. Unchanged files are hardlinked
between the backup instances, so you can simultaneously have backups
for the past 7 days, the past 4 weeks, etc, without too much expense
in overhead (at least if the bulk of your data doesn't change much
between backups). To keep things robust, I have a system dedicated to
the rsnapshot server - I seldom login to the system, and don't export
anything read/write, and don't run any unnecessary daemons, so it's
pretty unlikely that I'll accidentally mess things up. Once a month I
mirror the backup archive to one of a pair of external drives, which I
otherwise leave disconnected and turned off, and which I rotate
between home and office.
My thinking on having all these copies is:
- If I lose an individual system, I can restore from the backup server.
- If I lose the backup server, I can rebuild it from the most recent offline
mirror, or from the other systems.
- If I lose everything that's powered on, I can restore from the
- If I lose my home office, I still have a somewhat-stale copy at work.
- If I lose Northern California, well ... I don't know, yet :-).
I've considered having
a dedicated system well offsite, but I'm not certain it's worth the expense.
Nice things about this system:
- I exported the snapshot archive read-only, so I can easily verify
if things are
working using standard filesystem operations.
- Trivial to check an old config file without doing the tape-/cd-loading dance.
- Commodity hardware, if anything dies I can replace it in a couple hours.
- Disks are getting cheaper faster than I can fill them :-).
- Other than the mirror-and-rotate step, everything is automated, don't even
need to swap media.
- I now find upgrading a _breeze_. I used to do an elaborate dance involving
never being destructive, because I didn't trust my backups. Now I
do trust my
backups, and they are very easy to verify. I can upgrade, and compare what
the old system had to what the new system has and iterate until it has
everything I really need, rsync over the user data, and I'm good to go.
Basically, I've been a super-happy rsnapshot user for a year and a
half, and I can't think of a reason to stop being happy...
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