Ubuntu
bcache-tools package

  1. Bug #1887558
  2. Comment #21

Comment 21 for bug 1887558

Revision history for this message
Mitchell Dzurick (mitchdz) wrote : Re: Multipath JBOD storage devices are not shown via /dev/mapper but each path as a single device.

I have successfully created a kvm based reproducer.

1) get an image
$ wget https://cdimage.ubuntu.com/ubuntu-server/daily-live/pending/noble-live-server-amd64.iso

2) Create bcache disk
$ fallocate -l 20G image.img
$ make-bcache -C image.img

3) Boot into iso with multipathed bcache disk
$ kvm -m 2048 -boot d -cdrom ./noble-live-server-amd64.iso -device virtio-scsi-pci,id=scsi -drive file=image.img,if=none,id=sda,format=raw,file.locking=off -device scsi-hd,drive=sda,serial=0001 -drive if=none,id=sdb,file=image.img,format=raw,file.locking=off -device scsi-hd,drive=sdb,serial=0001

Select "Try or install Ubuntu" wait for the OS to load. Press F2 to escape to a shell to check multipathed devices.

You will see exactly what this bug describes - /dev/sd{a,b} is present with no multipathing.

Redo these steps without make-bcache on image.img and you will see a proper multipath /dev/mapper/mpatha present.