Backups / Dump etc

Matthew Seaman m.seaman at
Tue Jan 18 04:57:08 PST 2005

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



Dr Matthew J Seaman MA, D.Phil.                       8 Dane Court Manor
                                                      School Rd
PGP:         Tilmanstone
Tel: +44 1304 617253                                  Kent, CT14 0JL UK
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 305 bytes
Desc: not available
Url :

More information about the freebsd-questions mailing list