On Sat, Sep 10, 2005 at 10:34:29AM -0700, Octave Orgeron wrote: > > Does the snapshot take a full copy of the filesystem or does it only > copy the delta changes? If it's just regular snapshot, it does not meet > the features a union fs can provide. I've only used ZFS in a Solaris 10 > course, but it was a year old version:( So I'm not too familiar with > what has happened over the past year in development. >
ZFS is a copy on write filesystem (similar to WAFL), so a snapshot is an instantaneous operation that initially consumes zero additional space. As the active data diverges from the snapshot, it will gradually take up more space, proportional to the amount of delta between them. In addition, ZFS supports the notion of a "clone", which is a writable filesystem whose initial contents are that of a snapshot. Like snapshots, a clone initially takes up no extra space, but will consume more over time as the data diverges. We are actively thinking about how these technologies can be used with Zones and Live Upgrade (among other cases) to enable rapid deployment and upgrade. The idea of creating a "template zone" on a ZFS filesystem and then being able to instantaneously clone a new zone into existance is certainly appealing. But we're currently focused on ZFS integration; this is clearly a "phase two" item. - Eric -- Eric Schrock, Solaris Kernel Development http://blogs.sun.com/eschrock _______________________________________________ opensolaris-discuss mailing list opensolaris-discuss@opensolaris.org
