Update on putting WAL on ramdisk/

Some arbitrary data processing job

WAL on single drive: 7.990 rec/s
WAL on 2nd IDE drive: 8.329 rec/s
WAL on tmpfs: 13.172 rec/s

A huge jump in performance but a bit scary having a WAL that can
disappear at any time. I'm gonna workup a rsync script and do some
power-off experiments to see how badly it gets mangled.

This could be good method though when you're dumping and restore an
entire DB. Make a tmpfs mount, restore, shutdown DB and then copy the
WAL back to the HD.

I checked out the SanDisk IDE FlashDrives. They have a write cycle life
of 2 million. I'll explore more expensive solid state drives.