On Friday 01 October 2010 03:18:03 Frank D. wrote: > On Friday 01 October 2010 00:27:00 Chris Knadle wrote: > > > For USB flash and CF cards I recommend using the ext2 filesystem because > > it's unjournaled. I've yet to have a CF card using ext2 fail, and I've > > run some of them for 5 to 7 years. > > > > LogFS is also a new filesystem that seems to be meant for USB and CF > > cards, but it's not considered stable yet. I haven't tested it yet, but > > I'm looking forward to trying it out when it's a little more mature so > > that other machines can read it. > > I've never seen anything about LogFS before.
I believe it's new in the Linux kernel as of 2.6.34. It's mostly meant as a replacement for JFFS2. LogFS is still marked as "experimental" and "don't use it for anything other than testing" as of Linxu 2.6.36-rc6 (the latest -dev). Debian Unstable has a 'logfs-tools' package that adds 'mkfs.logfs' support -- I have it installed but haven't yet tried it. > Too bad you can't use > JFFS/UBIFS on top of CF/USB sticks.. > > -Frank I was told the OLPC boxes use JFFS2 on top of CF cards, and I've seen instructions of others that have put JFFS2 on CF cards -- but it's not recommended because JFFS2 is meant to do wear leveling on raw flash chips mounted on a board, not for CF cards which usually do wear leveling on their own. Thus if you run JFFS2 on CF cards, wear leveling is done twice and unpredictable as to what the results will be. Plus JFFS2 is meant to export raw flash chips as a device, which makes it difficult to do the same on something that already is a device, like a CF card. I've tried to install JFFS2 on a CF card and it's not easy. There's no 'mkfs.jffs2' program -- you have to first make a jffs2 loop filesystem of the particular target size, then use 'dd' to copy the image onto the CF card. And I think last I recall I had to run a custom kernel to get jffs2 support. Because of all this I avoided using it because if anything goes wrong it's a support headache -- i.e. it's not like you can just boot up a Knoppix CD to fun 'fsck' to fix a JFFS2 problem like you can with ext2. I've never tried UBIFS, and don't know too much about it. It seems to depend on the MTD layer that's meant for raw memory chips, though. And I'm also not able to find the userland utils required. I went searching to try to understand what UBIFS was and found this brief discussion, which touches on JFFS/UBIFS/LogFS: http://lwn.net/Articles/276025/ -- Chris -- Chris Knadle [email protected] _______________________________________________ Mid-Hudson Valley Linux Users Group http://mhvlug.org http://mhvlug.org/cgi-bin/mailman/listinfo/mhvlug Upcoming Meetings (6pm - 8pm) MHVLS Auditorium Oct 6 - Creating Browser Extensions for Firefox and Chrome Nov 3 - Open Source Hardware: Bugs, Beagles and Beyond Dec 1 - IBM's Open Client Deployment
