przemol...@poczta.fm wrote: >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 > > The email thread and document below gives you information about that:
http://www.opensolaris.org/jive/thread.jspa?messageID=19264䭀 http://www.opensolaris.org/os/community/zfs/docs/ondiskformatfinal.pdf Francois. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss -- This message posted from opensolaris.org _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
