Comment 27 for bug 595138

Problem detected on Ubuntu Studio x64 12.10 and reproduced under Studio x64 10.10 (both OSes running on same machine - two different hard drives).

Slightly the same situation as jdblair above (need to disable write cache on a disk at boot/resume time), except two differences :
    - classic hard drive, not an SSD
    - that drive is the boot drive

Added that new drive to be the target boot/root disk for 12.10 fresh install => turns out that kernel is unable to flush that disk's write cache when trying to shutdown, reboot or suspend (machine refuses to suspend and hangs on reboot/shutdown).
Bottom line : without disabling write caching on the boot disk at boot time, Ubuntu 12.10 is unusable.

Since hardware enumeration during boot is now completely dynamic, the different hard drives in the machine don't get the same /dev pointer each time, hence the UUID and bulk ID symlinks. So I added the following directive at the end of /etc/hdparm.conf :

    /dev/disk/by-id/ata-VB0250EAVER_9VMTTK1M {
        write_cache = off
    }

But it never seems to be executed at boot time, as you can see below :

    root@bigboy:/etc# hdparm -W /dev/disk/by-id/ata-VB0250EAVER_9VMTTK1M

    /dev/disk/by-id/ata-VB0250EAVER_9VMTTK1M:
    write-caching = 1 (on)

I also commented the "quiet" directive at the beginning of /etc/hdparm.conf, to have some log of what's going on, but to no avail.

Am I missing something ?