Failure to install 25.10 on multipath disk

Bug #2119429 reported by Olivier Gayot
18
This bug affects 2 people
Affects Status Importance Assigned to Milestone
curtin
Fix Committed
High
Olivier Gayot
subiquity
Fix Released
High
Olivier Gayot

Bug Description

I'm attempting to install Ubuntu server 25.10 on a multipath disk.

ProblemType: Bug
DistroRelease: Ubuntu 25.10
ProcVersionSignature: Ubuntu 6.15.0-4.4-generic 6.15.0
Uname: Linux 6.15.0-4-generic x86_64
NonfreeKernelModules: zfs
ApportVersion: 2.33.1-0ubuntu1
Architecture: amd64
CasperMD5CheckResult: pass
CasperVersion: 25.04.1
CloudArchitecture: x86_64
CloudID: nocloud
CloudName: unknown
CloudPlatform: nocloud
CloudSubPlatform: seed-dir (/var/lib/cloud/seed/nocloud)
Date: Mon Aug 4 08:17:05 2025
LiveMediaBuild: Ubuntu-Server 25.10 "Questing Quokka" - Daily amd64 (20250728)
Lsusb: Error: command ['lsusb'] failed with exit code 1:
Lsusb-t:

Lsusb-v: Error: command ['lsusb', '-v'] failed with exit code 1:
MachineType: QEMU Ubuntu 25.04 PC (i440FX + PIIX, 1996)
ProcEnviron:
 LANG=C.UTF-8
 PATH=(custom, no user)
 TERM=linux
ProcKernelCmdLine: BOOT_IMAGE=/casper/vmlinuz ---
Snap: subiquity 25.10-devel+git118.fc0f8ec7 ()
SnapChanges: no changes found
SnapConnections:

SnapSource: subiquity
SnapUpdated: False
SnapVersion: 6802 of snap /snap/subiquity/6802 of version 25.10-devel+git118.fc0f8ec7
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/04/2025
dmi.bios.release: 0.0
dmi.bios.vendor: Ubuntu distribution of EDK II
dmi.bios.version: 2025.02-3ubuntu2
dmi.chassis.type: 1
dmi.chassis.vendor: QEMU
dmi.chassis.version: pc-i440fx-plucky
dmi.modalias: dmi:bvnUbuntudistributionofEDKII:bvr2025.02-3ubuntu2:bd04/04/2025:br0.0:svnQEMU:pnUbuntu25.04PC(i440FX+PIIX,1996):pvrpc-i440fx-plucky:cvnQEMU:ct1:cvrpc-i440fx-plucky:sku:
dmi.product.name: Ubuntu 25.04 PC (i440FX + PIIX, 1996)
dmi.product.version: pc-i440fx-plucky
dmi.sys.vendor: QEMU

Related branches

Revision history for this message
Olivier Gayot (ogayot) wrote :
Olivier Gayot (ogayot)
information type: Private → Public
Changed in subiquity:
assignee: nobody → Olivier Gayot (ogayot)
status: New → In Progress
importance: Undecided → High
Revision history for this message
Olivier Gayot (ogayot) wrote :

error from curtin.log
---------------------
[...]
partition_kname=27-part1
An error occured handling 'partition-1': OSError - devname '27-part1' did not have existing syspath '/sys/class/block/27-part1'
[...]

Obviously, the "27-part1" identifier is wrong.
Looking at the code, it was generated in the partition_kname function by adding "-part1" to the return value of get_device_mapper_links("/dev/dm-0", first=True).

Specifying the first=True argument instructs get_device_mapper_links(...) to return the first devlink found (after lexical sorting).

get_device_mapper_links("/dev/dm-0") returns

["/dev/disk/by-diskseq/27",
 "/dev/disk/by-id/dm-name-mpatha",
 "/dev/disk/by-id/dm-uuid-mpath-0QEMU_QEMU_HARDDISK_MPIO0",
 "/dev/disk/by-id/scsi-0QEMU_QEMU_HARDSISK_MPIO0",
 "/dev/disk/by-id/wwn-0xQEMU_QEMU_HARDDISK_MPIO0",
 "/dev/mapper/mpatha"]

and out of these, only the following have a -part1 counterpart:

["/dev/disk/by-id/dm-name-mpatha",
 "/dev/disk/by-id/scsi-0QEMU_QEMU_HARDSISK_MPIO0",
 "/dev/disk/by-id/wwn-0xQEMU_QEMU_HARDDISK_MPIO0",
 "/dev/mapper/mpatha"]

but with first=True, we get the first one (i.e., /dev/disk/by-diskseq/27) which does not have a -part1 counterpart.

https://github.com/canonical/curtin/blob/5fd4993b45cda829b41b1173237e36a8b405ba8d/curtin/block/__init__.py#L123-L135
https://github.com/canonical/curtin/blob/5fd4993b45cda829b41b1173237e36a8b405ba8d/curtin/commands/block_meta.py#L1055-L1060

Olivier Gayot (ogayot)
Changed in curtin:
status: New → In Progress
Changed in subiquity:
status: In Progress → New
Changed in curtin:
assignee: nobody → Olivier Gayot (ogayot)
Olivier Gayot (ogayot)
Changed in curtin:
importance: Undecided → High
Revision history for this message
Olivier Gayot (ogayot) wrote :
Changed in curtin:
status: In Progress → Fix Committed
Changed in subiquity:
status: New → In Progress
Olivier Gayot (ogayot)
Changed in subiquity:
status: In Progress → Fix Committed
Revision history for this message
Ubuntu QA Website (ubuntuqa) wrote :

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
http://iso.qa.ubuntu.com/qatracker/reports/bugs/2119429

tags: added: iso-testing
Revision history for this message
Frank Heimes (fheimes) wrote :

While testing snapshot4 (actually the daily right after this, that also incl. the cloud-init fixes)
The installation was fine and I didn't ran into this multipath bug (here and LP#2118799) anymore.
So I'm closing at least the duplicate LP bug 2118799 as Fix Released.
Thank you Olivier !!

(However, leaving this bug here up to Olivier to close, since it was opened, hence is owned, by you.)

Olivier Gayot (ogayot)
Changed in subiquity:
status: Fix Committed → Fix Released
Revision history for this message
Olivier Gayot (ogayot) wrote :

Tested using the 25.10 server RC image. Installation using multipath was a success and the resulting system booted fine.

To post a comment you must log in.