local-fs fails to mount cdrom, forcing emergency mode boot

[Mikel Ward]

When I tried to boot my Ubuntu machine this morning, it dropped into emergency mode.

It did the same after rebooting.

Logs showed

=====

Apr 03 08:16:25 mikel-study mount[961]: mount: no medium found on /dev/sr0
Apr 03 08:16:25 mikel-study systemd[1]: cdrom.mount: Mount process exited, code=exited status=32
Apr 03 08:16:25 mikel-study systemd[1]: Failed to mount /cdrom.
-- Subject: Unit cdrom.mount has failed
...
-- Subject: Unit local-fs.target has failed
...
Apr 03 08:16:25 mikel-study systemd[1]: local-fs.target: Job local-fs.target/start failed with result 'dependency'.
Apr 03 08:16:25 mikel-study systemd[1]: local-fs.target: Triggering OnFailure= dependencies.
Apr 03 08:16:25 mikel-study systemd[1]: cdrom.mount: Unit entered failed state.
Apr 03 08:16:25 mikel-study systemd[1]: Reached target Emergency Mode.
-- Subject: Unit emergency.target has finished start-up

=====

Removing these two final entries from /etc/fstab and rebooting solved it.

/dev/dvd /dvd iso9660 ro 0 0
/dev/cdrom /cdrom iso9660 ro 0 0

Seems the same as https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1455683, but that was marked WONTFIX two years ago. Also not clear why it just started happening.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: systemd 229-4ubuntu16
ProcVersionSignature: Ubuntu 4.4.0-71.92-generic 4.4.49
Uname: Linux 4.4.0-71-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.5
Architecture: amd64
CurrentDesktop: XFCE
Date: Mon Apr 3 08:22:08 2017
InstallationDate: Installed on 2015-10-05 (545 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
MachineType: System manufacturer System Product Name
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-71-generic root=UUID=991bfd06-93fc-44f2-a592-cb3014d658b5 ro quiet splash
SourcePackage: systemd
SystemdDelta:
 [EXTENDED] /lib/systemd/system/rc-local.service → /lib/systemd/system/rc-local.service.d/debian.conf
 [EXTENDED] /lib/systemd/system/systemd-timesyncd.service → /lib/systemd/system/systemd-timesyncd.service.d/disable-with-time-daemon.conf
 [EXTENDED] /etc/systemd/system/display-manager.service → /lib/systemd/system/display-manager.service.d/xdiagnose.conf

 3 overridden configuration files found.
UpgradeStatus: Upgraded to xenial on 2016-05-04 (334 days ago)
dmi.bios.date: 10/21/2011
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 0703
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: P8Z68-V LX
dmi.board.vendor: ASUSTeK Computer INC.
dmi.board.version: Rev X.0x
dmi.chassis.asset.tag: Asset-1234567890
dmi.chassis.type: 3
dmi.chassis.vendor: Chassis Manufacture
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr0703:bd10/21/2011:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKComputerINC.:rnP8Z68-VLX:rvrRevX.0x:cvnChassisManufacture:ct3:cvrChassisVersion:
dmi.product.name: System Product Name
dmi.product.version: System Version
dmi.sys.vendor: System manufacturer