--On Friday, June 25, 2004 11:01 AM -0400 Chris Shenton Chris.Shenton@hq.nasa.gov wrote:
FreeBSD-5.x supports filesystem snapshots. I haven't played with them too much but they seem very quick to create, about a second or two, and I didn't have to take the filesystem offline or anything. See mksnap_ffs(8) and
http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/snapshots.html
According to the README (http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/ufs/ffs/README.snapshot?rev=1.4) snapshots suspend filesystem activity for 5 seconds on an 8Gb filesystem, and may affect performance if you're removing many small files that belong to a snapshot. These might be concerns depending how you're using snapshots and what the system is doing.
YMMV, do your own testing, I've only used snapshots when dump(8)ing live filesystems, which creates a snapshot, dumps it, then removes the snapshot (same as on many large NAS systems I've used). Seems to work nicely for that purpose.
Bryan