[plug] Backups

[James Devenish]

In message <410623A2.2060604 at postnewspapers.com.au>
on Tue, Jul 27, 2004 at 05:42:58PM +0800, Craig Ringer wrote:
> James: is `dump` capable of dumping a consistent point-in-time copy of
> a filesystem that's in read/write use, or must measures like read-only
> remounts or LVM snapshots be used?

"Must"? I wouldn't say so. I don't think it is any worse than tar (i.e.
won't lead to "filesystem corruption" as such). This remark is based
entirely on personal fortune with dump/restore systems appearing to be
robust. But I don't know whether this is by design or luck. Also, I
don't know how reliable the ext2/3 dump/restore utilities are -- but I
assume they're of high quality. Also, it's possible that last time I had
to restore, it was done on a system with snapshot support anyway (which
leaves your question unanswered).

> If you're thinking about differential or incremental backups intead, 
> then `dump` might again be a reasonable option, but I don't know enough 
> about it to say.

Dump is designed for this, but I guess if he's using write-once DVDs, it
might not be convenient to make lots and lots of incremental backups
with that type of medium. I can't remember how 'restore' handles
incremental backups (i.e. although it is designed specifically for such
usage, I can't remember how you 'tell it' the location of each backup).