Jim's Depository

I’ve enjoyed reading zbr’s blog postings about POHMELFS and the Elliptics network for years. With POHMELFS in the staging directories of Linux 2.6.33 and me needing to share some files across several machines, it is time to try it out.

1. Build myself some fresh new 2.6.33 kernels with POHMELFS enabled.
2. Look for a HOWTO of sorts, fail.
3. Check the server out with git: git clone http://www.ioremap.net/git/pohmelfs-server.git
4. Follow the included README
5. Fail, install autoconf.
6. Fail, finally discover that --with-kdir-path=<mylinuxsourc>/drivers/staging/pohmelfs/ is the right answer.
7. Fail, install libssl-dev.
8. make
9. make install
10. Copy /usr/local/bin/cfg over to the client machines.
11. Make a new filesystem to export mounted on /jim.
12. Start the server: fserver -r /jim
13. Go to a client machine:  #cfg -A add -a 1.1.1.1 -p 1025 -i 1 # mount -t pohmel -o idx=1 none /jim Killed
14. That isn’t good. dmesg reports there is a null pointer reference in the kernel.
15. Find two patches that will be in 2.6.33.1 related to “bdi” and not having a real backing device. Add them and make a new kernel.
16. Fail, badly. Please remember to change your version number in the kernel make file, lest you also forget the init ramdisk and make an unbootable system.
17. Success! With these patches I can now mount my pohmelfs partition! Unpacking a linux source tree is pleasently quick.
18. Failure! Chowning the source tree fills dmesg with things like…  pohmelfs_insert_hash: exist: parent: 856, ino: 879, hash: 9f4b42c5, len: 14, data: ‘README.syncppp’, new: ino: 37643, hash: 9f4b42c5, len: 14, data: ‘README.syncppp’. Chown silently and slowly fails.
19. Unmount and remount. Now chown hangs after a small amount of progress. No messages in dmesg this time. No changes make their way to the server.
20. I’m beginning to think Pohmelfs is not ready for me.

I will go shopping for other distributed file systems.