On Fri, 2005-01-07 at 13:49 -0600, John Goerzen wrote: > On Tue, Dec 14, 2004 at 10:39:25AM -0600, Dave Kleikamp wrote: > > On Tue, 2004-12-14 at 09:32 -0600, John Goerzen wrote: > > > Is there any practical way I could try to address this? I would rather > > > have the files truncated, or even re-linked to /lost+found or something, > > > than have them contain bad data. I also never seemed to encounter this > > > behavior with either ext2 or ext3. Was I just lucky, or is there > > > something fundamentally different about JFS? > > > > I'm not sure how I would address this in jfs. I don't know about ext3, > > Well, in ext3 one has some options (mount(8) quoted below). When I > mount it data=ordered, things seem fine. General wisdom holds that this > is the preferred way to go. It sounds like JFS is approximating > data-journal.
Actually, jfs does the equivalent of data=writeback. In the 2.4 kernel, it does the equivalent of data=ordered, but I changed the behavior do avoid a deadlock in 2.6 which I never found the correct fix for. The data=ordered behavior would prevent random data from showing up in a file, but it would not prevent the blocks of NULLs that you reported (if these are really file holes as I suspect). These would be caused when a file written non-sequentially was committed before it was completely written to. I'll have to look again at implementing the data=ordered behavior. > > data=journal / data=ordered / data=writeback > Specifies the journalling mode for file data. Metadata is > always journaled. To use modes other than ordered on the root > file system, pass the mode to the kernel as boot parameter, e.g. > rootflags=data=journal. > > journal > All data is committed into the journal prior to being > written into the main file system. > > ordered > This is the default mode. All data is forced directly > out to the main file system prior to its metadata being > committed to the journal. > > writeback > Data ordering is not preserved - data may be written into > the main file system after its metadata has been commit- > ted to the journal. This is rumoured to be the highest- > throughput option. It guarantees internal file system > integrity, however it can allow old data to appear in > files after a crash and journal recovery. -- David Kleikamp IBM Linux Technology Center _______________________________________________ Jfs-discussion mailing list [email protected] http://www-124.ibm.com/developerworks/oss/mailman/listinfo/jfs-discussion
