On Fri, Jul 07, 2006 at 11:59:29AM +0800, Raymond Xiong wrote: > It doesn't. Page 11 of the following slides illustrates how COW > works in ZFS: > > http://www.opensolaris.org/os/community/zfs/docs/zfs_last.pdf > > "Blocks containing active data are never overwritten in place; > instead, a new block is allocated, modified data is written to > it, and then any metadata blocks referencing it are similarly > read, reallocated, and written. To reduce the overhead of this > process, multiple updates are grouped into transaction groups, > and an intent log is used when synchronous write semantics are > required."(from http://en.wikipedia.org/wiki/ZFS) > > IN snapshot scenario, COW consumes much less disk space and is > much faster.
It says also that updating uberblock is an atomic operations. How is it achieved ? przemol _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
