Spent quite a bit of time on this and finally some progress.
This is not a critical bug anymore as I can now successfully reboot my lpar
with the -proposed kernel 5.0.0-38 for SRU Cycle 2019.12.02
During deployment of an lpar we configure DASD aliases via multipath,
usually this is required for disk performance however in our lab we are
always connecting to just 1 disk, so there is no need to i/o performance
in the test lab.
Also it is in question if DASD Aliases should not be used on an lpar as
they may only be for Zvm's, is this a proper supported configuration?
It would appear that having an active subchannel "chzdev -e
0.0.17e0-0.0.XXXX" is what perhaps is leading to this reboot problem.
The system actually is really "rebooting", it simply takes over 20
minutes to accomplish that task.
Why so long?
The assumption is that, once a channel is activated, the system will
build udev rules and rebuild the initramfs. Thus during the reboot
phase, the lpar must query each of the enabled disks to ensure they are
ok. Oddly , we don't see a delay in a shutdown command either.
This is just an assumption since I only see the problem once I activate
host multipath via chzdev. This problem has never been seen or
experienced in the past and is only isolated to this kernel. Xenial,Eoan
-proposed both restart just fine (For this SRU cycle)
It's possible that a commit made within this cycle has exposed this
issue. However for now there is a valid workaround.
In the lpar that Frank Heimes tested, he did NOT have multipathing
configured as his system rebooted without any delays, just as I
experienced after a fresh install (no multipathing configured)
I'm going to leave the severity at Medium as Frank Heimes will obtaining
more information about the disk multipathing on the lpar. To see if this
possibly is the culprit.
** Changed in: linux (Ubuntu)
Assignee: Sean Feole (sfeole) => (unassigned)
** Summary changed:
- Unable to reboot Disco on Ubuntu LPAR s390x (5.0.0-38)
+ Extreme Delayed Reboot with Disco on Ubuntu LPAR s390x (5.0.0-38)
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https://bugs.launchpad.net/bugs/1855237
Title:
Extreme Delayed Reboot with Disco on Ubuntu LPAR s390x (5.0.0-38)
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