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JFS on Linux = Surprisingly Lossy

I set up a RAID media server a couple years ago, and decided to give JFS2 a try, since it’s touted as being fast and reliable across the spectrum of usecases. My setup is primarily write-once-read-many, for storing the terabytes of audio and video recordings I’ve made over the last decade for project ruori and the like.

Several weeks ago, the power went out for an extended period of time while I was away, and, while it was on UPS backup, it failed to shutdown cleanly and the power was suddenly cut when the UPS ran out.

When I brought the machine back up, the volume wouldn’t mount, so I ran jfs_fsck on it. jfs_fsck said that the journal was corrupt, and started block-scanning. It came up with a pretty big list of files and directories that were irrevocably corrupt. Parts of a few of them got linked into /lost+found, but the majority simply vanished.

Funny thing is, I hadn’t made any changes to these files in several years. I could understand if maybe some very recent FS updates were lost due to write-caching, but why did it lose track of these ancient files?

This reminds me of the rampant table corruption of MS-DOS’s FAT16 filesystem, which couldn’t keep track of a needle dancing on the point of a needle.

So, plus one for backups of backups, and minus one for JFS on Linux. I think I’ll be rebuilding the machine with ZFS-fuse. Or OpenSolaris, for that matter.


Steve Mokris is a developer at Kosada, Inc.

Drupalcon tidbits

Cool things I learned about at Drupalcon DC include (but are not limited to) the following:

  • There is a Drupal 6 theme starter app whose maintainer is constantly improving it.
  • Usability studies have proven that I am not the only one who couldn’t figure out WTF to do with the welcome screen on my first Drupal install.
  • A lot of the modules that seem like they should be in core but probably won’t be in Drupal 7, are left out because Token is unlikely to be included and many of them rely on Token.

As usual, more coming…

DrupalCon 2009: First Impressions

I can positively affirm that the free tee-shirts given out with DrupalCon 09 registration are quality. The medium size fits me perfectly and the cotton is nice and soft and thick. Overall very wearable. Caveat: they’re not pre-shrunk so they will shrink.

I have a lot of actually relevant info to post but that will have to wait. Topics will include:

  • Theming tips and best practices
  • Awesome stuff (eg. fields!) that will be built-in to Drupal 7
  • Awesome stuff that won’t be in core in Drupal 7, and why it won’t (Hint: if it depends on something that won’t make core, it can’t go in core either)
  • Some other stuff.

Overall it’s been enjoyable and packed with information so far. I only wish I could go to more sessions.

memset() vs. bzero() — Ultimate Showdown

There are a few functions used to zero out memory on most unix variants. memset(), bzero(), and calloc() are all a few such functions. calloc() isn’t very useful for clearing already allocated memory, so it won’t be appearing much more in this article. However, the other two are somewhat more interesting than meets the eye.