[systemd-devel] Mount unit using device symlink

Lennart Poettering lennart at poettering.net
Wed Aug 13 12:17:02 PDT 2014

On Mon, 04.08.14 15:43, Patrick Hemmer (systemd at stormcloud9.net) wrote:

> I'm trying to mount a device using one of its symlinks, but systemd
> errors with "Timed out waiting for device dev-block-ec2-ephemeral0.device"
> The unit looks like:
>     [Unit]
>     After=ephemeral0-format.service
>     [Mount]
>     What=/dev/block/ec2/ephemeral0
>     Where=/mnt/ephemeral0
> /dev/block/ec2/ephemeral0 is a symlink set up by udev:
>     # udevadm info -q symlink -n /dev/xvdb
>     block/ec2/ephemeral0 disk/by-uuid/d57e2dd9-0062-448c-a914-0b6df045dafb
>     # ls -l /dev/block/ec2/ephemeral0
>     lrwxrwxrwx 1 root root 10 Aug  4 16:59 /dev/block/ec2/ephemeral0 ->
> ../../xvdb
> systemd automatically creates a unit for the /sys path, but not the symlink:
>     # systemctl list-units | grep 'xvdb\|ephemeral0'
>     sys-devices-vbd\x2d2064-block-xvdb.device                  loaded
> active plugged   /sys/devices/vbd-2064/block/xvdb

list-units only shows units that are not "following" other units. A
symlinked device node udev is aware of will show up as unit that
"follows" the primary device unit of your device (where "primary" means
the one that is named after the kernel name)...

"systemctl list-units -a" will show you all units systemd is currently
aware of. Do you see the device unit you are looking for there?


Lennart Poettering, Red Hat

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