AFS cache partition

[ezyang]

This seems to work reasonably (no journaling since we don't care about crash recovery, needs lots of inodes). 11G, since AFS checks for at least 5% extra room for our 10G cache.

  mkfs.ext4 -O ^has_journal -m 0 -N 1000000 /dev/xvds1

Need to migrate s-a and p-b, and all of the new F15 servers. Also update the Kickstart.

Given mild testing seems to have fixed major load problems, but we should wait for another 24hr cycle to be sure.

If corruption is detected, we don't want to fsck. Instead, blow the partition away and make a new filesystem. This requires us to do some boot script hacking.