On Apr 20, 2004 23:56 -0500, Vijayan Prabhakaran wrote: > Is it possible to use a separate journal device (one on a separate > drive or a partition) shared among more than 1 Ext3 file systems ? It is possible now to use an external block device for a single filesystem. The on-disk format is designed to allow multiple filesystems to share the same device, but that has never been fully implemented. At one point I had implemented a patch to mount a "jbd" filesystem with the journal device as the first step of having a shared journal device. Having the "jbd" device in /etc/fstab (before filesystems that use it) allows e2fsck to do journal replay on all of the filesystems before the journal starts to be used, or alternately dumps the journal data to an external file for later replay (e.g. if block devices are not available when e2fsck is run on the jbd device). It also allows the jbd code to configure the in-core code to be ready for external filesystems to connect to it. Finally, it also marks the block device as in-use so it is less likely that it will be overwritten accidentally. See the following email for the (ancient) patch. Most of the comments and a large fraction of the code in that email are still relevant, with the exception that all of the UUID handling already exists as libblkid in e2fsprogs, and it doesn't say what kernel version this is for (I'd suspect 2.3, but I'm not totally sure. Sadly, nobody commented on it at the time and it was lost in the mists of antiquity. > Subject: [PATCH][RFC] mountable journal devices > To: Ext2 development mailing list <ext2-devel@xxxxxxxxxxxxxxxxxxxxx> > Date: Wed, 8 Aug 2001 02:08:23 -0600 (MDT) http://marc.theaimsgroup.com/?l=ext2-devel&m=99725819513803 And the thread starting at discusses shared external journal devices: https://listman.redhat.com/archives/ext3-users/2001-November/msg00182.html Cheers, Andreas -- Andreas Dilger http://sourceforge.net/projects/ext2resize/ http://www-mddsp.enel.ucalgary.ca/People/adilger/ _______________________________________________ Ext3-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ext3-users
