Backups / Dump etc

[Matthew Seaman]

On Fri, Jan 14, 2005 at 10:49:44PM +0100, Anthony Atkielski wrote:
> John writes:
> 
> J> If you are running FreeBSD 5.x, you get the cool "L" option on
> J> dump which will automatically snapshot the mounted filesystems.
> 
> What exactly is meant by a "snapshot," and how much extra disk space
> does it require when dump runs?  I've seen the warnings when I run dump
> on a running multiuser system in 5.x, and I turned on the L option,
> since I'm not hurting on disk space, but I do wonder how much space it
> requires (I can't imagine a snapshot that doesn't require a lot of disk
> space).

Actually the snapshot requires practically no additional space: it's a
view of the filesystem at a particular point in time.  Any subsequent
modifications -- new or edited or deleted files, etc. are held in
memory: they do take up a bit more space, but only until dump(8)
finishes running and all of the recent filesystem traffic can be
merged.

	Cheers,

	Matthew

-- 
Dr Matthew J Seaman MA, D.Phil.                       8 Dane Court Manor
                                                      School Rd
PGP: http://www.infracaninophile.co.uk/pgpkey         Tilmanstone
Tel: +44 1304 617253                                  Kent, CT14 0JL UK
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