SR Garbage Collection running permanently

Tristis Oris

@Danp after some time GC task started automaticaly and running for 1 hour already. Still about 50%.

Tristis Oris

@Tristis-Oris GC done, ~5 items removed, ~20 left.

olivierlambert

Good, so it is working

Tristis Oris

@olivierlambert is it some limit for items removal per run?

olivierlambert

The GC is doing one chain after another. We told XenServer team back in 2016 that it could probably merge multiple chains at once, but they told us it was too risky. So we did not focus on that. Patience is key there. Clearly, we'll do better in the future.

Tristis Oris

@olivierlambert got it. Will see what happens in few days.

olivierlambert

It will accelerate. First merges are the slowest ones, but then it's going faster and faster.

Tristis Oris

2 days, few backup cycles, snapshots amount won't descrease.

Danp

@Tristis-Oris Check SMlog for further exceptions.

tjkreidl

@Tristis-Oris Note that if the SR storage device is around 90% or more full, a coalesce may not work. You have to either delete or move then enough storage so that there is adequate free space.
How full is the SR? That said, a coalesce process can take up to 24 hours to complete. I wonder if this shows up and with what progress when you run "xe task-list" ?

Tristis Oris

@Danp No, can't find any exceptions.
that typical log for now, it repeating a lot of times:

Jan 20 00:02:00 host SM: [2736362] Kicking GC
Jan 20 00:02:00 host SM: [2736362] Kicking SMGC@93d53646-e895-52cf-7c8e-df1d5e84f5e4...
Jan 20 00:02:00 host SM: [2736362] utilisation 40394752 <> 34451456
*
Jan 20 00:02:00 host SM: [2736362] VDIs changed on disk: ['34fa9f2d-95fa-468e-986c-ade22b92b1f3', '56b94e20-01ae-4da1-99f8-03aa901da64f', 'a75c6e7b-7f8d-4a4b-99$
Jan 20 00:02:00 host SM: [2736362] Updating VDI with location=34fa9f2d-95fa-468e-986c-ade22b92b1f3 uuid=34fa9f2d-95fa-468e-986c-ade22b92b1f3
*
Jan 20 00:02:00 host SM: [2736362] lock: released /var/lock/sm/93d53646-e895-52cf-7c8e-df1d5e84f5e4/sr
Jan 20 00:02:00 host SMGC: [2736466] === SR 93d53646-e895-52cf-7c8e-df1d5e84f5e4: gc ===
Jan 20 00:02:00 host SM: [2736466] lock: opening lock file /var/lock/sm/93d53646-e895-52cf-7c8e-df1d5e84f5e4/running
*
Jan 20 00:02:00 host SMGC: [2736466] Found 0 cache files
Jan 20 00:02:00 host SM: [2736466] lock: tried lock /var/lock/sm/93d53646-e895-52cf-7c8e-df1d5e84f5e4/sr, acquired: True (exists: True)
Jan 20 00:02:00 host SM: [2736466] ['/usr/bin/vhd-util', 'scan', '-f', '-m', '/var/run/sr-mount/93d53646-e895-52cf-7c8e-df1d5e84f5e4/*.vhd']
Jan 20 00:02:00 host SM: [2736614] lock: opening lock file /var/lock/sm/93d53646-e895-52cf-7c8e-df1d5e84f5e4/sr
Jan 20 00:02:00 host SM: [2736614] sr_update {'host_ref': 'OpaqueRef:3570b538-189d-6a16-fe61-f6d73cc545dc', 'command': 'sr_update', 'args': [], 'device_config':$
Jan 20 00:02:00 host SM: [2736614] lock: closed /var/lock/sm/93d53646-e895-52cf-7c8e-df1d5e84f5e4/sr
Jan 20 00:02:01 host SM: [2736466]   pread SUCCESS
*
Jan 20 00:02:01 host SMGC: [2736466] SR 93d5 ('VM Sol flash') (73 VDIs in 39 VHD trees):
Jan 20 00:02:01 host SMGC: [2736466]         *70119dcb(50.000G/45.497G?)
Jan 20 00:02:01 host SMGC: [2736466]             e6a3e53a(50.000G/107.500K?)
*
Jan 20 00:02:01 host SM: [2736466] lock: released /var/lock/sm/93d53646-e895-52cf-7c8e-df1d5e84f5e4/sr
Jan 20 00:02:01 host SMGC: [2736466] Got sm-config for *70119dcb(50.000G/45.497G?): {'vhd-blocks': 'eJzFlrFuwjAQhk/Kg5R36Ngq5EGQyJSsHTtUPj8WA4M3GDrwBvEEDB2yEaQQ$
*
Jan 20 00:02:01 host SMGC: [2736466] No work, exiting
Jan 20 00:02:01 host SMGC: [2736466] GC process exiting, no work left
Jan 20 00:02:01 host SM: [2736466] lock: released /var/lock/sm/93d53646-e895-52cf-7c8e-df1d5e84f5e4/gc_active
Jan 20 00:02:01 host SMGC: [2736466] In cleanup
Jan 20 00:02:01 host SMGC: [2736466] SR 93d5 ('VM Sol flash') (73 VDIs in 39 VHD trees): no changes
Jan 20 00:02:01 host SM: [2736466] lock: closed /var/lock/sm/93d53646-e895-52cf-7c8e-df1d5e84f5e4/running

@tjkreidl Free space is enough. I never see GC job running for a long, so never see it at other pools or after fix. Have no any coalesce in queue.
xe task-list show nothing.

Maybe i need to cleanup bad VDIs manually for first time?

tjkreidl

@Tristis-Oris It wouldn't hurt to do a manual cleanup. Not sure if a reboot might help, but strange that no task is showing as active. Do you have other SRs on which you can try a scan/coalesce?
Are there any VMs in a weird power state?

Tristis Oris

@tjkreidl nothing unusual.
I found same issue on another 8.3 pool, another SR, but never seen related GC tasks. No exceptions at log.
But no problems with 3rd 8.3 pool.

SR scan don't trigger GC, can i run it manually?

tjkreidl

@Tristis-Oris By manually, do you mean from the CLI vs. from the GUI? If so, then:
xe sr-scan sr-uuid=sr_uuid
Check your logs (probably /var/log/SMlog) and run "xe task-list" to see what, if anything, is active.

Tristis Oris

@tjkreidl but that same scan as ?

Tristis Oris

I guess I'm a little confused.
Probably, after fix all bad snapshots been removed, and now they are exist only for hatled (archive) VMs. They got backup only once with such job:

so without backup tasks, GC for vdi chains not running. Is it safe to remove them manually, or better to run backup task again? (that very long and not required).

tjkreidl

@Tristis-Oris Do first verify you have good backups before considering deleting snapshots. You could also just export the snapshots associated with the VMs..
As to the GUI vs. CLI, it should do the same thing, but if it runs, it should show up in the task list.