<![CDATA[Auto coalescing of disks]]>Hi,

On my SR I have 8 VDI's that require coalesce. Most of these are between 20-80GB in size with a chain length of 1-4. How long roughly would this take and when can I expect this to happen? Is it actively happening in the background?

  • I have no snapshots
  • No orphaned VDI's
  • The disk is a thick provisioned lvmohba
  • There is 1.63TB free on the disk
  • I'm running XO server 5.71.2, XenServer 7.4.0

Question 2 - can I force coalesce by rescanning the disk? If I rescan the disk, is there any chance of this causing an outage?

Thanks,
Chris.

]]>https://xcp-ng.org/forum/topic/4449/auto-coalescing-of-disksRSS for NodeSun, 06 Sep 2026 20:10:21 GMTWed, 07 Apr 2021 15:37:30 GMT60<![CDATA[Reply to Auto coalescing of disks on Tue, 20 Apr 2021 08:40:37 GMT]]>@olivierlambert thanks - I'll continue to look into it.

]]>https://xcp-ng.org/forum/post/38709https://xcp-ng.org/forum/post/38709Tue, 20 Apr 2021 08:40:37 GMT<![CDATA[Reply to Auto coalescing of disks on Fri, 09 Apr 2021 11:23:49 GMT]]>You have weird issues on your storage (I/O error on badly named VHD, hard to tell without investigating further)

]]>https://xcp-ng.org/forum/post/38417https://xcp-ng.org/forum/post/38417Fri, 09 Apr 2021 11:23:49 GMT<![CDATA[Reply to Auto coalescing of disks on Fri, 09 Apr 2021 09:52:52 GMT]]>@olivierlambert Hi, I've been keeping an eye on dmesg and getting the following -

[Thu Apr 8 20:26:51 2021] device-mapper: ioctl: unable to remove open device VG_XenStorage--767a9d9c--55aa--0898--fe10--400ee856bdce-clone_ba7ea2dd--4684--4cc9--9ccd--ba1909cda656_1

I don't know if this could possibly be related to the exceptions I am seeing?

Thanks,
Chris.

]]>https://xcp-ng.org/forum/post/38412https://xcp-ng.org/forum/post/38412Fri, 09 Apr 2021 09:52:52 GMT<![CDATA[Reply to Auto coalescing of disks on Thu, 08 Apr 2021 09:30:49 GMT]]>@olivierlambert thanks. The only other thing - I was using templates so I notice on my storage that one block consists of 6 base copies & 3 VDI's.

In this format, I have issues migrating and snapshotting them. However, if I power them off, snapshot, run a full clone, and use the new clone they work fine (migratable, snapshottable, bootable). Any ideas why this might be and could this be the cause of the coalesce issue?

Thanks,
Chris.

]]>https://xcp-ng.org/forum/post/38361https://xcp-ng.org/forum/post/38361Thu, 08 Apr 2021 09:30:49 GMT<![CDATA[Reply to Auto coalescing of disks on Thu, 08 Apr 2021 08:36:49 GMT]]>It's on the SR here. The storage code is reporting the issue, so that's why coalesce isn't happening.

]]>https://xcp-ng.org/forum/post/38356https://xcp-ng.org/forum/post/38356Thu, 08 Apr 2021 08:36:49 GMT<![CDATA[Reply to Auto coalescing of disks on Thu, 08 Apr 2021 08:35:10 GMT]]>@olivierlambert ah - would the input/output error be on the nodes itself or the SR?

We have seen this input/output error before when attempting to snapshot or migrate VM's -

 "code": "SR_BACKEND_FAILURE_81",
  "params": [
    "",
    "Failed to clone VDI [opterr=['XENAPI_PLUGIN_FAILURE', 'multi', 'CommandException', 'Input/output error']]",
    ""
  ],

I can reboot the nodes but would be a little hesitant due to potential downtime, etc. Would restarting the tool stack help?

dmesg isn't reporting anything particularly concerning.

Appreciate your support on this,
Chris.

]]>https://xcp-ng.org/forum/post/38355https://xcp-ng.org/forum/post/38355Thu, 08 Apr 2021 08:35:10 GMT<![CDATA[Reply to Auto coalescing of disks on Thu, 08 Apr 2021 08:13:49 GMT]]>Input/output error isn't a good sign 😕

Try to reboot all your hosts and see if the issue persist. Also check dmesg.

]]>https://xcp-ng.org/forum/post/38354https://xcp-ng.org/forum/post/38354Thu, 08 Apr 2021 08:13:49 GMT<![CDATA[Reply to Auto coalescing of disks on Wed, 07 Apr 2021 18:43:29 GMT]]>@olivierlambert thanks - that's definitely all the hosts. Only three on this system. Any way to check each host at a deeper level?

Chris

]]>https://xcp-ng.org/forum/post/38334https://xcp-ng.org/forum/post/38334Wed, 07 Apr 2021 18:43:29 GMT<![CDATA[Reply to Auto coalescing of disks on Wed, 07 Apr 2021 17:30:00 GMT]]>By default the UI will only display running hosts. Be sure to have an empty search field.

]]>https://xcp-ng.org/forum/post/38329https://xcp-ng.org/forum/post/38329Wed, 07 Apr 2021 17:30:00 GMT<![CDATA[Reply to Auto coalescing of disks on Wed, 07 Apr 2021 16:24:01 GMT]]>@r1 They are reporting to be at least, all green on the UI -

85dd30d1-768c-4de5-8939-4d8d49571b44-image.png

Any way I can check further?

Chris.

]]>https://xcp-ng.org/forum/post/38328https://xcp-ng.org/forum/post/38328Wed, 07 Apr 2021 16:24:01 GMT<![CDATA[Reply to Auto coalescing of disks on Wed, 07 Apr 2021 15:58:25 GMT]]>@chrispage1 said in Auto coalescing of disks:

Apr 7 16:07:09 node-01 SMGC: [20480] text = session.xenapi.host.call_plugin(slave, "on-slave", "multi", args)

Seems the issue is here. Are all your slaves in pool healthy?

]]>https://xcp-ng.org/forum/post/38326https://xcp-ng.org/forum/post/38326Wed, 07 Apr 2021 15:58:25 GMT<![CDATA[Reply to Auto coalescing of disks on Wed, 07 Apr 2021 15:53:02 GMT]]>Thanks for the very quick response! I've tail'd the SMlog and as you suspected I'm getting -

Apr  7 16:07:09 node-01 SMGC: [20480] SR 767a ('Pool') (43 VDIs in 16 VHD trees): showing only VHD trees that changed:
Apr  7 16:07:09 node-01 SMGC: [20480]         *80da56bc[VHD](10.000G//4.684G|n)
Apr  7 16:07:09 node-01 SMGC: [20480]             *4c8eff6e[VHD](80.000G//10.035G|n)
Apr  7 16:07:09 node-01 SMGC: [20480]                 *c16bbd77[VHD](80.000G//68.000M|n)
Apr  7 16:07:09 node-01 SMGC: [20480]                     22229e00[VHD](80.000G//80.164G|n)
Apr  7 16:07:09 node-01 SMGC: [20480]             c09ea342[VHD](40.000G//40.086G|n)
Apr  7 16:07:09 node-01 SMGC: [20480]             40647cba[VHD](10.000G//244.000M|n)
Apr  7 16:07:09 node-01 SMGC: [20480]             *310a023f[VHD](10.000G//1.078G|n)
Apr  7 16:07:09 node-01 SMGC: [20480]                 *f6618327[VHD](10.000G//140.000M|n)
Apr  7 16:07:09 node-01 SMGC: [20480]                     *524d192c[VHD](10.000G//5.262G|n)
Apr  7 16:07:09 node-01 SMGC: [20480]                         914771aa[VHD](10.000G//10.027G|n)
Apr  7 16:07:09 node-01 SMGC: [20480]                     *47f40b1b[VHD](10.000G//252.000M|n)
Apr  7 16:07:09 node-01 SMGC: [20480]                         *18f02843[VHD](10.000G//5.828G|n)
Apr  7 16:07:09 node-01 SMGC: [20480]                             c7a0b227[VHD](10.000G//10.027G|n)
Apr  7 16:07:09 node-01 SMGC: [20480]
Apr  7 16:07:09 node-01 SMGC: [20480] *~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Apr  7 16:07:09 node-01 SMGC: [20480]          ***********************
Apr  7 16:07:09 node-01 SMGC: [20480]          *  E X C E P T I O N  *
Apr  7 16:07:09 node-01 SMGC: [20480]          ***********************
Apr  7 16:07:09 node-01 SMGC: [20480] gc: EXCEPTION <class 'XenAPI.Failure'>, ['XENAPI_PLUGIN_FAILURE', 'multi', 'CommandException', 'Input/output error']
Apr  7 16:07:09 node-01 SMGC: [20480]   File "/opt/xensource/sm/cleanup.py", line 2712, in gc
Apr  7 16:07:09 node-01 SMGC: [20480]     _gc(None, srUuid, dryRun)
Apr  7 16:07:09 node-01 SMGC: [20480]   File "/opt/xensource/sm/cleanup.py", line 2597, in _gc
Apr  7 16:07:09 node-01 SMGC: [20480]     _gcLoop(sr, dryRun)
Apr  7 16:07:09 node-01 SMGC: [20480]   File "/opt/xensource/sm/cleanup.py", line 2573, in _gcLoop
Apr  7 16:07:09 node-01 SMGC: [20480]     sr.coalesce(candidate, dryRun)
Apr  7 16:07:09 node-01 SMGC: [20480]   File "/opt/xensource/sm/cleanup.py", line 1542, in coalesce
Apr  7 16:07:09 node-01 SMGC: [20480]     self._coalesce(vdi)
Apr  7 16:07:09 node-01 SMGC: [20480]   File "/opt/xensource/sm/cleanup.py", line 1732, in _coalesce
Apr  7 16:07:09 node-01 SMGC: [20480]     vdi._doCoalesce()
Apr  7 16:07:09 node-01 SMGC: [20480]   File "/opt/xensource/sm/cleanup.py", line 1181, in _doCoalesce
Apr  7 16:07:09 node-01 SMGC: [20480]     VDI._doCoalesce(self)
Apr  7 16:07:09 node-01 SMGC: [20480]   File "/opt/xensource/sm/cleanup.py", line 693, in _doCoalesce
Apr  7 16:07:09 node-01 SMGC: [20480]     self.sr._updateSlavesOnResize(self.parent)
Apr  7 16:07:09 node-01 SMGC: [20480]   File "/opt/xensource/sm/cleanup.py", line 2492, in _updateSlavesOnResize
Apr  7 16:07:09 node-01 SMGC: [20480]     vdi.fileName, vdi.uuid, slaves)
Apr  7 16:07:09 node-01 SMGC: [20480]   File "/opt/xensource/sm/lvhdutil.py", line 300, in lvRefreshOnSlaves
Apr  7 16:07:09 node-01 SMGC: [20480]     text = session.xenapi.host.call_plugin(slave, "on-slave", "multi", args)
Apr  7 16:07:09 node-01 SMGC: [20480]   File "/usr/lib/python2.7/site-packages/XenAPI.py", line 263, in __call__
Apr  7 16:07:09 node-01 SMGC: [20480]     return self.__send(self.__name, args)
Apr  7 16:07:09 node-01 SMGC: [20480]   File "/usr/lib/python2.7/site-packages/XenAPI.py", line 159, in xenapi_request
Apr  7 16:07:09 node-01 SMGC: [20480]     result = _parse_result(getattr(self, methodname)(*full_params))
Apr  7 16:07:09 node-01 SMGC: [20480]   File "/usr/lib/python2.7/site-packages/XenAPI.py", line 237, in _parse_result
Apr  7 16:07:09 node-01 SMGC: [20480]     raise Failure(result['ErrorDescription'])
Apr  7 16:07:09 node-01 SMGC: [20480]
Apr  7 16:07:09 node-01 SMGC: [20480] *~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Apr  7 16:07:09 node-01 SMGC: [20480] * * * * * SR 767a9d9c-55aa-0898-fe10-400ee856bdce: ERROR
Apr  7 16:07:09 node-01 SMGC: [20480]

This is right at the end of my log. Any ideas from the logs what might be causing this? Input/output error seems fairly ambiguous?

Chris.

]]>https://xcp-ng.org/forum/post/38325https://xcp-ng.org/forum/post/38325Wed, 07 Apr 2021 15:53:02 GMT<![CDATA[Reply to Auto coalescing of disks on Wed, 07 Apr 2021 15:46:09 GMT]]>@chrispage1 said in Auto coalescing of disks:

Question 2 - can I force coalesce by rescanning the disk? If I rescan the disk, is there any chance of this causing an outage?

This automatically kicks GC apart from regular schedule. Rescanning won't cause outage. Do check /var/log/SMlog for any obvious error causing GC to not work.

]]>https://xcp-ng.org/forum/post/38324https://xcp-ng.org/forum/post/38324Wed, 07 Apr 2021 15:46:09 GMT