The mailing list eventually went nowhere, including someone helping me out privately. He seemed to think it was a udev issue, which was highly amusing as the udev (and systemd) binaries were running from the very devices they believed weren't ready yet.
Here is the final scorecard. I have 3 systems, all using btrfs with raid0 across two devices. Both root and home are separate subvolumes on that. System 1 (workstation - above report): systemd brings the system up but times out waiting to mount home. Setting /home to nofail in fstab and then running mount -a from a console works just fine. This is the only system where the two drives are identical - they are exactly the same SSD models and firmware versions on the same controller. (Note system fails to boot if they are on different controllers which wasn't a problem with earlier Ubuntu versions.) Booting with upstart works fine and is how I have now configured the system. System 2 (laptop): the two devices are wrapped in LUKS+dmcrypt. They are decrypted at boot and then there is a pause, and then finally everything comes up. Most of the time that pause is 3 minutes, but sometimes is a few seconds. Again no problems in earlier Ubuntu releases. System 3 (server): Like system 1, it is bare devices but in this case they are about the same capacity but from different vendors. Everything works perfectly, and if anything boots a bit faster than earlier Ubuntu releases. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to systemd in Ubuntu. https://bugs.launchpad.net/bugs/1447879 Title: fscking btrfs consisting of multiple partitions fails Status in systemd package in Ubuntu: New Bug description: I have two SSDs in raid0 (striped) configuration with my root and home as separate subvolumes. This setup has worked fine for several Ubuntu releases, but fails with systemd on 15.04. systemd does manage to mount root, but then looks like it is trying to fsck the "disk" for home which is nonsensical. After 90 seconds it drops into a useless shell where I can't fix things. Relevant lines from /etc/fstab UUID=3ff68715-0daa-4e44-8de2-0997f36d8ab6 / btrfs defaults,device=/dev/disk/by-id/ata-Crucial_CT960M500SSD1_1347095B97B4-part1,device=/dev/disk/by-id/ata-Crucial_CT960M500SSD1_1338094EA3CA-part1,autodefrag,compress=lzo,subvol=@ 0 1 UUID=3ff68715-0daa-4e44-8de2-0997f36d8ab6 /home btrfs defaults,device=/dev/disk/by-id/ata-Crucial_CT960M500SSD1_1347095B97B4-part1,device=/dev/disk/by-id/ata-Crucial_CT960M500SSD1_1338094EA3CA-part1,autodefrag,compress=lzo,subvol=@home 0 2 Note how the lines are identical except for the subvol value. I originally didn't have the device= bits either but had to add it for root because of how `btrfs device scan` is run. With or without it present doesn't make any difference for home. There is no such problem booting with upstart ProblemType: Bug DistroRelease: Ubuntu 15.04 Package: systemd 219-7ubuntu3 ProcVersionSignature: Ubuntu 3.19.0-15.15-generic 3.19.3 Uname: Linux 3.19.0-15-generic x86_64 ApportVersion: 2.17.2-0ubuntu1 Architecture: amd64 CurrentDesktop: XFCE Date: Thu Apr 23 19:45:38 2015 MachineType: System manufacturer System Product Name ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.19.0-15-generic root=UUID=3ff68715-0daa-4e44-8de2-0997f36d8ab6 ro rootflags=subvol=@ nomdmonddf nomdmonisw init=/sbin/upstart SourcePackage: systemd SystemdDelta: [EXTENDED] /lib/systemd/system/systemd-timesyncd.service → /lib/systemd/system/systemd-timesyncd.service.d/disable-with-time-daemon.conf 1 overridden configuration files found. UpgradeStatus: Upgraded to vivid on 2015-04-23 (0 days ago) dmi.bios.date: 08/13/2013 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: 2104 dmi.board.asset.tag: To be filled by O.E.M. dmi.board.name: P8Z77-V PRO dmi.board.vendor: ASUSTeK COMPUTER INC. dmi.board.version: Rev 1.xx dmi.chassis.asset.tag: Asset-1234567890 dmi.chassis.type: 3 dmi.chassis.vendor: Chassis Manufacture dmi.chassis.version: Chassis Version dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr2104:bd08/13/2013:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKCOMPUTERINC.:rnP8Z77-VPRO:rvrRev1.xx:cvnChassisManufacture:ct3:cvrChassisVersion: dmi.product.name: System Product Name dmi.product.version: System Version dmi.sys.vendor: System manufacturer To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1447879/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp