Re: Question on backups using rsync
in response to the whole preceding chain.
On Tuesday 20 December 2005 23:01, Alvin Oga wrote:
automated backup is worthless for that precise reason about corrupted main
systems and there's hundreds of reasons/problems that causes the
main system or backup system to have bad data rendering either or both
backups should be saved not mirrored ... and it's NOT the same thing
Yes, I agree. This is why I take advantage of rsync always unlinking the files
before it updates them, which means I can simply rotate the backups, but
rather than copying, I just copy the hardlinks.
Essentially it becomes a poor man's revision control system, allowing me to go
to any particular day or month.
Thus, I get the convenience of the automated backup, plus the certainty that
'bad things' on the client doesn't result in 'worse things' on the backup
This, however, does translate in your partition eventually having to handle
_millions_ of files, and it is ideal to back this mess up from time to time,
to guard from corruption. (Remember that although a file may exist in 1000
different places, it's still the _same_ file if only hardlinks are used, and
is thus succeptable to deliberate or random failures)
I've always worked with the idea of two different kinds of backups.
1) a copy of the critical files (accounting, databases, spreadsheets
etc.) that are needed for day to day operations in the event of
corruption or accidental deletion and the like. These are just copies,
in my case, of just a couple of directories. I don't need long term
storage, just a few days/weeks of copies that I can refer to incase I
2) a system backup with a snapshot of the entire system. With hours and
hours of configuration and setup on my boxes, Id like to have
occaisional "snapshots" of the whole system. Then if I lose a machine
(hardrive crash, theft, flood whatever) or blow the system up somehow, I
can recreate the whole thing a-new relatively easily. In this case, the
actual critical data from above would theoretically already be stored
and retrievable somewhere (and usable on any system) and therefore,
these snapshots do not have to be done as frequently. Just whenever a
major system change happens, or every couple months to include small
incremental system creep.
so for case 1 I'd love something offsite, like a dead webpage or
something where I can just automatically load these files and leave'em
for now. case 2 needs bigger storage probably and maybe something like
partitionimage with the files split onto cds/dvds and stored somewhere
safe. The infrequency of this case allows less convenient means of storage.