When I take a snapshot of a filesystem (or pool) and pass -r to get all the sub-filesystems, am I getting the state of all the sub-filesystem snapshots "at the same instant," or is it essentially equivalent to making the sub-filesystem snapshots one at a time as I would have to do if -r weren''t available? Thanks, -- Dave Abrahams BoostPro Computing http://www.boostpro.com
On Sun, Feb 22, 2009 at 11:59 AM, David Abrahams <dave at boostpro.com> wrote:> > When I take a snapshot of a filesystem (or pool) and pass -r to get all > the sub-filesystems, am I getting the state of all the sub-filesystem > snapshots "at the same instant," or is it essentially equivalent to > making the sub-filesystem snapshots one at a time as I would have to do > if -r weren''t available?Google for "zfs snapshot recursive atomic" leads me to: http://docs.sun.com/app/docs/doc/819-5461/gdfdt?a=view Which says: Recursive ZFS snapshots are created quickly as one atomic operation. The snapshots are created together (all at once) or not created at all. The benefit of atomic snapshots operations is that the snapshot data is always taken at one consistent time, even across descendent file systems. -- Mike Gerdts http://mgerdts.blogspot.com/
On Feb 22, 2009, at 1:04 PM, Mike Gerdts wrote:> On Sun, Feb 22, 2009 at 11:59 AM, David Abrahams <dave at boostpro.com> > wrote: >> >> When I take a snapshot of a filesystem (or pool) and pass -r to get >> all >> the sub-filesystems, am I getting the state of all the sub-filesystem >> snapshots "at the same instant," or is it essentially equivalent to >> making the sub-filesystem snapshots one at a time as I would have >> to do >> if -r weren''t available? > > Google for "zfs snapshot recursive atomic" leads me to: > > http://docs.sun.com/app/docs/doc/819-5461/gdfdt?a=view > > Which says: > > Recursive ZFS snapshots are created quickly as one atomic operation. > The snapshots are created together (all at once) or not created at > all. The benefit of atomic snapshots operations is that the snapshot > data is always taken at one consistent time, even across descendent > file systems.Thanks, Mike. That''s what I needed to know. Cheers, -- David Abrahams BoostPro Computing http://boostpro.com