[Bug 1681909] [NEW] kdump is not captured in remote host when kdump over ssh is configured

[Launchpad Bug Tracker]

You have been subscribed to a public bug by Ubuntu Foundations Team Bug Bot (crichton):

[Impact]

* Kdump over network (like NFS mount or SSH dump) relies on network-
online target from systemd. Even so, there are some NICs that report
"Link Up" state but aren't ready to transmit packets. This is a
generally bad behavior that is credited probably to NIC firmware delays,
usually not fixable from drivers. Some adapters known to act like this
are bnx2x, tg3 and ixgbe.

* Kdump is a mechanism that may be a last resort to debug complex/hard
to reproduce issues, so it's interesting to increase its reliability /
resilience. We then propose here a solution/quirk to this issue on
network dump by adding a retry/delay mechanism; if it's a network dump,
kdump will retry some times and sleep between the attempts in order to
exclude the case of NICs that aren't ready yet but will soon be able to
transmit packets.

* Although first reported by IBM in PowerPC arch, the scope for this
issue is the NIC, and it was later reported in x86 arch too.

[Test case]

Usually it's difficult to naturally reproduce this issue in a deterministic way, but we have an artificial test case on comment #24 of this LP.
Also, we have a report from this bug in which the user managed to reproduce the problem consistently - it's fixed after testing our solution.

[Regression potential]

There's not a clear regression potential here since it's just a retry/delay mechanism. Some potential problems may come from bad coding in the script.
The delay between attempts is only 3 sec per iteration, so it shouldn't block the kdump progress for a high amount of time at once.

** Affects: ubuntu-power-systems
     Importance: Low
         Status: In Progress

** Affects: makedumpfile (Ubuntu)
     Importance: Medium
     Assignee: Guilherme G. Piccoli (gpiccoli)
         Status: In Progress

** Affects: makedumpfile (Ubuntu Xenial)
     Importance: Medium
     Assignee: Thadeu Lima de Souza Cascardo (cascardo)
         Status: In Progress

** Affects: makedumpfile (Ubuntu Bionic)
     Importance: Medium
     Assignee: Thadeu Lima de Souza Cascardo (cascardo)
         Status: In Progress

** Affects: makedumpfile (Ubuntu Cosmic)
     Importance: Medium
     Assignee: Thadeu Lima de Souza Cascardo (cascardo)
         Status: In Progress

** Affects: makedumpfile (Ubuntu Disco)
     Importance: Medium
     Assignee: Thadeu Lima de Souza Cascardo (cascardo)
         Status: In Progress

** Affects: makedumpfile (Ubuntu Eoan)
     Importance: Medium
     Assignee: Guilherme G. Piccoli (gpiccoli)
         Status: In Progress


** Tags: architecture-ppc64le kernel-da-key patch ppc64el-kdump sts triage-g
-- 
kdump is not captured in remote host when kdump over ssh is configured
https://bugs.launchpad.net/bugs/1681909
You received this bug notification because you are a member of Ubuntu Sponsors Team, which is subscribed to the bug report.