I just upgraded from F14 to F16 so this is my first attempt at systemd
and I think I found a bug/issue. (I'm running systemd-37-3.fc16.x86_64)
My /dev/md0 (not a bootable disk thank goodness) is encrypted with luks.
My crypttab contains:
encrypt_storage /dev/md0 /mnt/usbkey/storage.key
cipher=aes-cbc-essiv:sha256,size=256,hash=sha1
systemd would fail with:
[ 26.576425] systemd-cryptsetup[951]: crypt_init() failed: Block
device required
That tells me that systemd is trying to access /dev/md0 before it
actually created the device. So,
after much documentation reading I created a local cryptsetup.target file:
[Unit]
Description=Encrypted Volumes Wait
Requires=mnt-usbkey.mount dev-md0.device
After=mnt-usbkey.mount dev-md0.device
The mnt-usbkey.mount ensures that the USB flash key is loaded early.
(Before cryptsetup.target). That is not germane to this discussion.
The problem is the most of the time my changes fail. Occasionally it
would work, but mostly not. So after examining the logs and some debug,
I think the problem is a race with systemd or something.
The problem is dev-md0.device becomes 'plugged' before the /dev/md0 is
actually created/ready. From the log:
[ 26.136607] systemd[1]: dev-md0.device changed dead -> plugged
[ 26.136614] systemd[1]: Job dev-md0.device/start finished, result=done
[ 26.136634] systemd[1]: sys-devices-virtual-block-md0.device changed
dead -> plugged
[ 26.136691] systemd[1]: About to execute:
/lib/systemd/systemd-cryptsetup attach encrypt_storage /dev/md0
/mnt/usbkey/storage.key cipher=aes-cbc-essiv:sha256,size=256,hash=sha1
...
[ 26.576425] systemd-cryptsetup[951]: crypt_init() failed: Block
device required
However, the md0 is not really up. Because the above command only fails
with /dev/md0 is missing. AND 500 milliseconds later...
[ 26.634837] md/raid:md0: raid level 5 active with 4 out of 4 devices,
algorithm 2
[ 26.634839] RAID conf printout:
[ 26.634840] --- level:5 rd:4 wd:4
[ 26.634842] disk 0, o:1, dev:sdb1
[ 26.634844] disk 1, o:1, dev:sdc1
[ 26.634845] disk 2, o:1, dev:sdd1
[ 26.634847] disk 3, o:1, dev:sde1
[ 26.634877] md0: detected capacity change from 0 to 2250456956928
...
[ 26.672387] systemd[1]:
dev-disk-by\x2did-md\x2duuid\x2d432b22e3:364555c6:f3927192:227cec7f.device
changed dead -> plugged
So I came to the conclusion that I had to modifty crypttab to be:
encrypt_storage
/dev/disk/by-id/md-uuid-432b22e3:364555c6:f3927192:227cec7f
/mnt/usbkey/storage.key cipher=aes-cbc-essiv:sha256,size=256,hash=sha1
With that device change, it appears to work.
If this means dev-md0.device is not accurate as an indicator of /dev/md0
being present, then I guess every other reference such as in my
cryptsetup.target would need to be changed too.
This whole issue seems odd and certainly not intuitive. I thought I was
instructing systemd correcty, telling it to have the depending on
dev-md0.device. I would have thought any 'uuid' /dev/disk would simply
be an alias, but that does not appear to be the case.
Note that my kernel cmdline has 'rd.md=0 rd.dm=0 rd.luks=0' so none of
this is setup earlier than systemd.
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