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nova server-migration-show wrongly reports zero progress

asked 2017-01-13 22:01:19 -0600

This is on Mitaka. I am block-migrating an instance with a 10GB secondary ephemeral disk.

To my disappointment, the server-migration-show command reports zero progress:

$ nova --os-compute-api-version 2.25 server-migration-show 5f87e455-6ebd-4cd7-b111-8dd78cf3489e 31
+------------------------+--------------------------------------+
| Property               | Value                                |
+------------------------+--------------------------------------+
| created_at             | 2017-01-14T02:48:46.000000           |
| dest_compute           | comp0003                             |
| dest_host              | -                                    |
| dest_node              | -                                    |
| disk_processed_bytes   | 0                                    |
| disk_remaining_bytes   | 0                                    |
| disk_total_bytes       | 0                                    |
| id                     | 31                                   |
| memory_processed_bytes | 0                                    |
| memory_remaining_bytes | 0                                    |
| memory_total_bytes     | 0                                    |
| server_uuid            | 5f87e455-6ebd-4cd7-b111-8dd78cf3489e |
| source_compute         | comp0001                             |
| source_node            | -                                    |
| status                 | running                              |
| updated_at             | 2017-01-14T02:48:53.000000           |
+------------------------+--------------------------------------+

Checking ephemeral storage on the destination node shows that there is progress, and migration completes eventually. Submitted the equivalent API with curl yields the same result, so that this is not a nova client issue.

Progress copying memory is, by the way, reported by this API.

Is there anything I can do to get a more accurate description of the ongoing migration?

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Comments

Maybe 'info migrate' using QEMU monitor would help? (virsh qemu-monitor-command --hmp <domain> info migrate...) http://www.linux-kvm.org/page/Migrati...</domain>

volenbovsky gravatar imagevolenbovsky ( 2017-01-14 06:17:18 -0600 )edit

Thanks, that's very useful, although currently the command times out trying to acquire a lock. Still, I did a virsh domjobinfo and found that no disk migration stats are reported. Most probably qemu simply doesn't do that. I will post a conclusion when I have one.

Bernd Bausch gravatar imageBernd Bausch ( 2017-01-14 06:53:48 -0600 )edit

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answered 2017-01-14 07:46:20 -0600

It seems that qemu keeps migration statistics in the MigrationState struct in include/migration/migration.h; see source code. Disk statistics don't seem to be included. So my problem is caused by a limitation in qemu.

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Comments

Just out of curiosity, what version of QEMU are you running? This might be useful information that we can feed back into the API reference docs as a known issue:

http://developer.openstack.org/api-re...

mriedem gravatar imagemriedem ( 2017-01-14 09:30:57 -0600 )edit

--Actually I pointed above to info migrate, but then looked into https://qemu.weilnetz.de/w64/2012/201... and see that is 'query-migrate'. I think what is reason for behaviour is explained in http://www.spinics.net/linux/fedora/l... ...

volenbovsky gravatar imagevolenbovsky ( 2017-01-14 13:49:43 -0600 )edit

I think that corresponds to Bernd wrote in answer',as in Libvirt ML it is written by Nikolay: "There is no disks statistics when migrating with VIR_MIGRATE_NON_SHARED_* for qemu that supports nbd. The reason is that disks are copied via disk mirroring and not in the scope of migration job itself'

volenbovsky gravatar imagevolenbovsky ( 2017-01-14 13:52:29 -0600 )edit

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Asked: 2017-01-13 22:01:19 -0600

Seen: 169 times

Last updated: Jan 14 '17