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CA-81025: In case of cross-pool migrate remove rrd-metrics for the vm from the source host #1013

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siddharthv commented Feb 11, 2013

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@ghost ghost assigned mcclurmc Feb 12, 2013

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jonludlam commented Feb 12, 2013

Assigning to @mcclurmc for review - in particular, why is this code path different from other VM lifecycle operations in as far as the RRDs go?

Jon Ludlam and I just reviewed this code, and we think that it's unnecessary. Earlier in this function, we already call rrd_migrate, so the rrds will be transferred to the remote host. Somewhere in this code we also call VM destroy, and this function calls remove_rrd on the pool master.

And because the rrds have been removed on the master, the Xapi_sync.do_sync function (https://github.com/siddharthv/xen-api/blob/master/ocaml/xapi/xapi_sync.ml#L23) will (every two hours, see: https://github.com/siddharthv/xen-api/blob/master/ocaml/xapi/xapi_periodic_scheduler_init.ml#L33) sync blobs between the master and slaves, and ensure that the rrds that were deleted on the master also get cleaned up on the slaves.

You can set a FIST point on the master to reduce this interval from 2 hours to 10 minutes. I bet that if you set this FIST point (by doing 'touch /etc/fist_reduce_blob_sync_interval'), then cross-pool migrate a VM, and then wait ten minutes, the RRDs on the slave will be removed by the sync code.

Siddarth, can you test that this works as expected without your change? If it does work this way, then let's close this pull request. Thanks,

Mike

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siddharthv commented Feb 20, 2013

Hi Mike,

I performed the following test,

I had 2 hosts A and B with two VMs running on host A. I enabled fist points on both hosts. Next I cross-pool migrated VMs from host A to host B. The rrd-metrics for the VMs are present on host B but the rrd-metrics for the VMs cross-pool migrated are still present on host A.

I intended this patch to remove the rrd-metrics for the cross pool migrated VMs on the source host.

Thanks,
Siddharth

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simonjbeaumont commented Sep 26, 2013

@siddharthv, what's the status of this now? I'm guessing it can be closed given its age?

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siddharthv commented Sep 26, 2013

This patch fixes the problem. It's waiting on Mike and JonL!
I think they need to review it before it can be closed

@ghost ghost assigned simonjbeaumont Nov 14, 2013

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simonjbeaumont commented Nov 14, 2013

For my sins, @jonludlam suggested I take a look at this in the next few weeks...

@jonludlam jonludlam added the master label Jul 28, 2014

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simonjbeaumont commented Nov 13, 2014

More investigation done on ticket. This was required for the archived RRDs to be cleaned up but would need to be done not here (possibly on the slave), but on the master so they don't just re-appear on the next sync.

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simonjbeaumont commented Nov 13, 2014

Superseded by #2015.

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