Bug 47934 – [4.2] Migration does not converge

Bug 47934 - [4.2] Migration does not converge


Summary:	[4.2] Migration does not converge

Status:	CLOSED INVALID

Product:	UCS
Classification:	Unclassified
Component:	Virtualization - UVMM
Version:	UCS 4.2
Hardware:	Other Linux

Importance:	P5 normal (vote)
Target Milestone:	---
Assigned To:	UCS maintainers
QA Contact:	UCS maintainers

URL:
Keywords:

Depends on:	47617
Blocks:
	Show dependency tree / graph

Reported:	2018-10-09 15:42 CEST by Valentin Heidelberger
Modified:	2018-10-23 10:43 CEST (History)
CC List:	8 users (show)

See Also:
What kind of report is it?:	Bug Report
What type of bug is this?:	4: Minor Usability: Impairs usability in secondary scenarios
Who will be affected by this bug?:	1: Will affect a very few installed domains
How will those affected feel about the bug?:	5: Blocking further progress on the daily work
User Pain:	0.114
Enterprise Customer affected?:	Yes
School Customer affected?:
ISV affected?:
Waiting Support:	Yes
Flags outvoted (downgraded) after PO Review:
Ticket number:	2018082021000474, 2018090421000967, 2018100821000804
Bug group (optional):
Max CVSS v3 score:

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Description Valentin Heidelberger

2018-10-09 15:42:18 CEST

+++ This bug was initially created as a clone of Bug #47617 +++

Most of the customer's virt systems are still on UCS 4.2. To be able to update the systems to 4.3 smoothly they need a backport of this bugfix for 4.2.

The live migration of a VM with 16 GiB RAM and 8 CPUs did non converge; UVMM returned an error with did not contain any specific details - probably just a timeout.

# virsh domjobinfo $DOM
Job type:         Unbounded
Time elapsed:     5499859      ms
Data processed:   530,696 GiB
Data remaining:   170,289 MiB
Data total:       12,009 GiB
Memory processed: 530,696 GiB
Memory remaining: 170,289 MiB
Memory total:     12,009 GiB
Dirty rate:       30740        pages/s
Iteration:        1695
Constant pages:   5252035
Normal pages:     138835932                                                                                                                                                        
Normal data:      529,617 GiB
Expected downtime: 1245         ms
Setup time:       167          ms

This is a known (Qemu) problem: <https://wiki.qemu.org/Features/AutoconvergeLiveMigration>

Using --postcopy the VM was migrated ~1 minute:
# virsh migrate --domain $DOM --live --persistent --undefinesource --postcopy --postcopy-after-precopy --verbose qemu://$DEST/system

UVMMd should use --postcopy by default.
Alternative 1: --auto-converge --auto-converge-initial 20 --auto-converge-increment 10
Alternative 2: Add UCRV to make it configurable.

Comment 1 Valentin Heidelberger

2018-10-16 17:48:52 CEST

Customer updates manually with virsh migrate and the necessary --postcopy parameter. They don't need a backport anymore. If another customer needs this, it can be reopened.

Comment 2 Stefan Gohmann

2018-10-23 10:42:43 CEST

OK

Comment 3 Stefan Gohmann

2018-10-23 10:43:01 CEST

Nothing to release