--- Ivan Voras <[EMAIL PROTECTED]> wrote: > Unga wrote: > > Hi all > > > > I'm looking for papers or documentation covering > > details of the UFS2 Journaling implementation of > the > > FreeBSD. > > > > Please give me links to them if you guys know any. > > > > Many thanks in advance. > > There's no such thing as UFS2 Journalling in FreeBSD > (yet). There's > "gjournal" which is journaling on the data layer > (below the file system, > and only with very limited integration with the file > system). This > implementation is not documented (except for usage > here: > http://www.freebsd.org/cgi/man.cgi?query=gjournal&manpath=FreeBSD+7.0-RELEASE), > > but there's a small (and very old) high-level > overview in my proposal on > which the current gjournal is based, here: > http://wiki.freebsd.org/gjournal_proposal . Ignore > the bits about > "delay-commit". See also here: > http://docs.freebsd.org/cgi/getmsg.cgi?fetch=3624+0+/usr/local/www/db/text/2006/freebsd-geom/20060625.freebsd-geom > >
Ivan, thanks for the links. What I mean is configure journaling via gjournal(8) for the UFS file system. I lost some files, specially Firefox's book marks, history, etc. after a power failure on FreeBSD 7.0. What else lost is not known yet. I'm looking for a file system protection mechanism. I understand there are two mechanism in FreeBSD: Soft Update and gjournal. I have following questions in this regard: 1. "Pawel (pjd) has reimplemented gjournal with hooks in the file system code so it can properly do file system journaling." - http://wiki.freebsd.org/gjournal) So, the gjournal is a Journaled File System which can be used against file system corruptions in the event of power failure or system crash? 2. "Unfortunately, gjournal cannot replace a journaling filesystem. At least, a fsck is still needed on the journaled device/filesystem after a crash." -(http://wiki.freebsd.org/gjournal) Is it now confirmed that gjournal does not require fsck after a power failure or system crash? 3. "To ensure that data is stored on the data provider, the gjournal sync command should be used after calling sync(2)." - gjournal(8) Who should issue this command? user manually? 4. "Size should be chosen based on provider's load, and not on its size. It is not recommended to use gjournal for small file systems" - gjournal(8) So how do I know what should be the size of the journal before it is created? Does it log anywhere if the journal size is too small for the system load? 5. "Some UFS implementations avoid journaling and instead implement soft updates: they order their writes in such a way that the on-disk file system is never inconsistent, or that the only inconsistency that can be created in the event of a crash is a storage leak. To recover from these leaks, the free space map is reconciled against a full walk of the file system at next mount." - (http://en.wikipedia.org/wiki/Journaling_file_system) So the disadvantage of Soft Update is it is necessary to run fsck after reboot in event of a crash or power failure? 6. On the same hard disk for various BSD partitions, is it possible to use both Soft Update and gjournal, Eg. Soft Update for / , gjournal for /usr? 7. In, gjournal label [-fhv] [-s jsize] dataprov [jprov] What is the unit of the size? Kind regards Unga ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ _______________________________________________ firstname.lastname@example.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"