Linked by Amjith Ramanujam on Fri 1st Aug 2008 15:32 UTC, submitted by Daniel Sieger
Today, support for metadata journaling has been added to NetBSD's implementation of the Berkeley Fast File System (FFS), eliminating the need for lengthy file system checks after a crash or power failure. Support for converting existing file systems to use the new journaling capabilities is provided as well. See the official announcement
for all the details.
Thread beginning with comment 325301
To view parent comment, click here.
To read all comments associated with this story, please click here.
To view parent comment, click here.
To read all comments associated with this story, please click here.
Recent Original Stories
Recent Comments
Headlines
Random Comments
Random Stories
Random OS Link
Member since:
2005-07-08
Yes...but not in the same way other people do journaling. Apparently they've metadata journaling - just like XFS, JFS or ext3 with the "data=writeback" mount option.
But if you only journal the metadata, you're only sure that the metadata is safe - not the data. IOW, you don't get metadata corruption (you don't need to fsck after a hard reboot), but the data of the file you were writting at the time of the reboot can be lost/corrupted. In XFS for example a file can get completely zeroed after a hard reboot.
There're two main ways to workaround this. One, journal the data (like in ext3 with the data=journal option) - but it's too slow. Second, write the data of a file before you journal its metadata, so that even in the event of a hard reboot, you are sure that the content of the file are not corrupted/lost - they may be outdated (the data was in ram and was not written to disk when the reboot happened), but not lost/corrupte (you may get a "corrupted" file in the sense that the process which was writting to it doesn't finishes writting what it was doing, but certainly you don't get rubbish). This is what ext3 does by default - it harms performance, but it's worth of it, specially for desktops.
You can also avoid completely the journaling, like zfs/btrfs do, but that's not really a "journaling mode"