[Bug 1473903] Re: parted will generate two devices when adding one partition on mpath device
Mathieu Trudel-Lapierre
mathieu.tl at gmail.com
Thu Sep 10 14:50:36 UTC 2015
Don't both device names actually work fine though? I couldn't find any
blocking issue to leaving both in place, since they don't seem to
interfere with any operation of the system. This would certainly
constitute the least-intrusive change, on account that there would be no
change required.
Otherwise, there doesn't seem to be a straightforward way to fix this.
We basically have two not great options to contend with (unless someone
else can think of another):
1) Patch parted to write -part partitions instead of -p.
This is fine for the installed system, but means we'd need to revert SRUs already done for multipath-tools in the installer -- where we expect to see -p partitions always, and rewrite them to -part at the end (since there will be just kpartx on the installed system), modify partman-multipath to pick up all partitions and make them -part. There remains the issue of rewriting fstab later on, when comes the time to migrate to multipath 0.5.0 (which changes the partition names in other ways too, so unavoidable).
2) Fix kpartx rules either by disabling them or making them use -p only.
This would fix the installed system (since parted creates p partitions itself) and detected partitions on drives at boot would show up correctly, but we'd need to do other SRU changes to installer bits to not rewrite /etc/fstab to use -part as a partition separator. This is apparently a simpler change, but means we also need to deal with changing fstab on upgrade for those who use -part, which makes it dangerous and very intrusive.
I'd love to get some guidance on this, but I'm thinking not changing
anything for now is the best option; although if there is any effect in
having both devices show up and we need to stop it, then 1) would be
best.
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https://bugs.launchpad.net/bugs/1473903
Title:
parted will generate two devices when adding one partition on mpath
device
Status in multipath-tools package in Ubuntu:
Invalid
Status in parted package in Ubuntu:
Triaged
Bug description:
Problem Description
=============================
Two deivce created when creating 1 partition on a mpath device:
% sudo parted /dev/mapper/mpath2
GNU Parted 2.3
Using /dev/mapper/mpath2
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) p
Model: Linux device-mapper (multipath) (dm)
Disk /dev/mapper/mpath2: 284GB
Sector size (logical/physical): 512B/4096B
Partition Table: msdos
Number Start End Size Type File system Flags
(parted) mkpart
mkpart mkpartfs
(parted) mkpart
Partition type? primary/extended? primary
File system type? [ext2]?
Start? 0%
End? 10%
Device /dev/mapper/mpath2p1 not found
device-mapper: table ioctl on failed: No such device or address
Device /dev/mapper/mpath2p1 not found
device-mapper: table ioctl on failed: No such device or address
(parted) p
Model: Linux device-mapper (multipath) (dm)
Disk /dev/mapper/mpath2: 284GB
Sector size (logical/physical): 512B/4096B
Partition Table: msdos
Number Start End Size Type File system Flags
1 1049kB 28.4GB 28.4GB primary
(parted) q
Information: You may need to update /etc/fstab.
% ls /dev/mapper/mpath2*
/dev/mapper/mpath2 /dev/mapper/mpath2p1 /dev/mapper/mpath2-part1
%
Steps to Reproduce
===================================
1. install ubuntu 14.04.3 on a system which has mpath device
2. try to partition the mpath device, add one partition
---uname output---
Linux dilllp1 3.19.0-22-generic #22~14.04.1-Ubuntu SMP Wed Jun 17 10:03:39 UTC 2015 ppc64le ppc64le ppc64le GNU/Linux
Userspace tool common name: parted
Userspace rpm: parted, version: 2.3-19ubuntu1
The userspace tool has the following bit modes: 64-bit
== Comment: #2 - David Heller <hellerda at us.ibm.com> - 2015-07-09 20:16:11 ==
Hi Ping,
Are you sure that /dev/mapper/mpath2p1 device was not left over from
install, and perhaps existed before you did the parted? Remember
there were some changes to multipath in the installer, and the
installer now uses mpathXpX, and the running os uses mpathX-partX.. I
think that is right?
If the two devices truly were created in the same parted operation, if
you can reproduce it, can you run "udevadm monitor -p" during the
operation, and provide the output? thx.
== Comment: #3 - Ping Tian Han <pthan at cn.ibm.com> - 2015-07-09 22:03:53 ==
(In reply to comment #2)
> Hi Ping,
>
> Are you sure that /dev/mapper/mpath2p1 device was not left over from
> install, and perhaps existed before you did the parted? Remember there were
Yes, I'm pretty sure the device wasn't left over from install:
% ls /dev/mapper/mpath4*
/dev/mapper/mpath4
% sudo parted /dev/mapper/mpath4*
GNU Parted 2.3
Using /dev/mapper/mpath4
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) p
Error: /dev/mapper/mpath4: unrecognised disk label
(parted) mklabel msdos
(parted) p
Model: Linux device-mapper (multipath) (dm)
Disk /dev/mapper/mpath4: 284GB
Sector size (logical/physical): 512B/4096B
Partition Table: msdos
Number Start End Size Type File system Flags
(parted) mkpart 1
parted: invalid token: 1
Partition type? primary/extended? primary
File system type? [ext2]?
Start? 0%
End? 10%
Device /dev/mapper/mpath4p1 not found
device-mapper: table ioctl on failed: No such device or address
Device /dev/mapper/mpath4p1 not found
device-mapper: table ioctl on failed: No such device or address
(parted) p
Model: Linux device-mapper (multipath) (dm)
Disk /dev/mapper/mpath4: 284GB
Sector size (logical/physical): 512B/4096B
Partition Table: msdos
Number Start End Size Type File system Flags
1 1049kB 28.4GB 28.4GB primary
(parted) q
Information: You may need to update /etc/fstab.
% ls /dev/mapper/mpath4*
/dev/mapper/mpath4 /dev/mapper/mpath4p1 /dev/mapper/mpath4-part1
%
> some changes to multipath in the installer, and the installer now uses
> mpathXpX, and the running os uses mpathX-partX.. I think that is right?
>
> If the two devices truly were created in the same parted operation, if you
> can reproduce it, can you run "udevadm monitor -p" during the operation, and
> provide the output? thx.
No problem, I'll upload the result.
== Comment: #5 - Ping Tian Han <pthan at cn.ibm.com> - 2015-07-09 22:09:59 ==
(In reply to comment #4)
> Created attachment 100079 [details]
> udevadm monitor -p outputs when bug reproduced
This is the outputs when creating mpath4-part2.
== Comment: #6 - Vaishnavi Bhat <vaish123 at in.ibm.com> - 2015-07-10 11:08:42 ==
Hi Ping Tian Han,
Can you please try to install the latest parted package from
http://ftp.gnu.org/gnu/parted/ and check if the issue is reproduced ?
Thank you.
== Comment: #7 - Ping Tian Han <pthan at cn.ibm.com> - 2015-07-12 22:05:17 ==
(In reply to comment #6)
> Hi Ping Tian Han,
>
> Can you please try to install the latest parted package from
> http://ftp.gnu.org/gnu/parted/ and check if the issue is reproduced ?
>
> Thank you.
The latest 3.2 version doesn't have this problem on dilllp1.
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