I attempted to reproduce this issue in a VM and wasn't succesful. I essentially copied the tgtbasedmpaths test but made the backing disk bcache cache before setting up the targets.
1) create vm $ lxc launch ubuntu-daily:noble --vm n-vm $ lxc shell n-vm # apt install -y lsscsi multipath-tools open-iscsi tgt 2) setup virtual multipathd disk ``` targetname="iqn.2016-11.foo.com:target.iscsi" cwd=$(pwd) testdir="/mnt/tgtmpathtest" localhost="127.0.0.1" portal="${localhost}:3260" maxpaths=4 backfn="backingfile" expectwwid="60000000000000000e00000000010001" testdisk="/dev/disk/by-id/wwn-0x${expectwwid}" ### Setup mpath devices # Restart tgtd to make sure modules are all loaded service tgt restart || echo "Failed to restart tgt" >&2 # prep SINGLE test file truncate --size 100M ${backfn} make-bcache -C ${backfn} # create target tgtadm --lld iscsi --op new --mode target --tid 1 -T "${targetname}" # allow all tomake-bcache -C ${backfn} bind the target tgtadm --lld iscsi --op bind --mode target --tid 1 -I ALL # set backing file tgtadm --lld iscsi --op new --mode logicalunit --tid 1 --lun 1 -b "${cwd}/${backfn}" # scan for targets (locally) iscsiadm --mode discovery --type sendtargets --portal ${localhost} # login echo "login #1" iscsiadm --mode node --targetname "${targetname}" --portal ${portal} --login # duplicate this session (always 1) for i in $(seq 2 ${maxpaths}) do echo "extra login #${i}" iscsiadm --mode session -r 1 --op new done udevadm settle sleep 5 # sleep a bit to allow device to be created. ``` And can confirm the disks are using bcache FS by: # udevadm info /dev/dm-0 | grep ID_FS_TYPE E: ID_FS_TYPE=bcache Things look fine and as they should to me # lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS sda 8:0 0 10G 0 disk ├─sda1 8:1 0 9G 0 part / ├─sda14 8:14 0 4M 0 part ├─sda15 8:15 0 106M 0 part /boot/efi └─sda16 259:0 0 913M 0 part /boot sdb 8:16 0 100M 0 disk └─mpatha 252:0 0 100M 0 mpath sdc 8:32 0 100M 0 disk └─mpatha 252:0 0 100M 0 mpath sdd 8:48 0 100M 0 disk └─mpatha 252:0 0 100M 0 mpath sde 8:64 0 100M 0 disk └─mpatha 252:0 0 100M 0 mpath # multipath -ll mpatha (360000000000000000e00000000010001) dm-0 IET,VIRTUAL-DISK size=100M features='0' hwhandler='0' wp=rw |-+- policy='service-time 0' prio=1 status=active | `- 10:0:0:1 sde 8:64 active ready running |-+- policy='service-time 0' prio=1 status=enabled | `- 7:0:0:1 sdb 8:16 active ready running |-+- policy='service-time 0' prio=1 status=enabled | `- 8:0:0:1 sdc 8:32 active ready running `-+- policy='service-time 0' prio=1 status=enabled `- 9:0:0:1 sdd 8:48 active ready running # ls /dev/mapper control mpatha I'm not sure if I'm setting up this test incorrectly or not. In fact if I run `udevadm test` I see the bcache udev rules fail. # udevadm test /dev/mapper/mpatha < cut here > dm-0: /usr/lib/udev/rules.d/69-bcache.rules:21 RUN 'kmod load bcache' dm-0: /usr/lib/udev/rules.d/69-bcache.rules:22 RUN 'bcache-register $tempnode' dm-0: /usr/lib/udev/rules.d/69-bcache.rules:26 Importing properties from results of 'bcache-export-cached /dev/dm-0' dm-0: Starting 'bcache-export-cached /dev/dm-0' Successfully forked off '(spawn)' as PID 2197. dm-0: Process 'bcache-export-cached /dev/dm-0' failed with exit code 1. dm-0: /usr/lib/udev/rules.d/69-bcache.rules:26 Command "bcache-export-cached /dev/dm-0" returned 1 (error), ignoring < cut here > -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1887558 Title: Multipath JBOD storage devices are not shown via /dev/mapper but each path as a single device. To manage notifications about this bug go to: https://bugs.launchpad.net/bcache-tools/+bug/1887558/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs