Comment 19 for bug 990913

Precise is using a 3.2.0 kernel. There is a known MD bug that affects some 3.2.x and 3.3.x kernels, that seems like it might be relevant to this problem. See:

http://www.spinics.net/lists/raid/msg39004.html

and the rest of that thread. Note the mention of possible racing in scripts.

Unfortunately for us, the lead MD developer does not test with Ubuntu, or with any other Debian-based distro. (He only uses SUSE.) So if there are any complex race conditions or other problems created by Ubuntu's udev scripts or configs or whatever, he might not uncover them in his testing, and the level of assistance he can provide is limited. (He and the others on the linux-raid list are indeed helpful, but I'm not sure that very many of them use Ubuntu, and the level of the discussion there is fairly technical and probably well beyond what most Ubuntu users could follow.)

Now that Canonical has announced the plan to eliminate the Alternate installer and merge all installer functionality (presumably including RAID) into the regular Desktop installer, it seems likely that the number of users setting up RAID arrays will increase. (I am using Desktop myself, not Server).

For some time now, it has been possible to set up and (to a limited degree) manage software RAID arrays on Ubuntu without any knowledge of the command line. So there are Desktop users who are using RAID arrays, thinking they are safeguarding their data. But when the complex creature known as linux software RAID breaks down, as it has with this bug, they are quickly in over their heads. Given that RAID bugs can destroy the user's data, just about the worst thing that can happen, it would seem prudent to either (1) actively discourage non-expert users from using RAID, or (2) make Ubuntu's implementation of RAID far more reliable.