Bug 1477717 - Sanlock init failed with unhelpful error message "Sanlock exception"
Sanlock init failed with unhelpful error message "Sanlock exception"
Status: MODIFIED
Product: Red Hat Enterprise Virtualization Manager
Classification: Red Hat
Component: sanlock (Show other bugs)
4.1.4
All Linux
unspecified Severity high
: ovirt-4.2.0
: ---
Assigned To: Nir Soffer
Natalie Gavrielov
: ZStream
Depends On:
Blocks: 1497940
  Show dependency treegraph
 
Reported: 2017-08-02 13:19 EDT by nijin ashok
Modified: 2017-11-02 04:09 EDT (History)
7 users (show)

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Story Points: ---
Clone Of:
: 1497940 (view as bug list)
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Type: Bug
Regression: ---
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oVirt Team: Storage
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---


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External Trackers
Tracker ID Priority Status Summary Last Updated
oVirt gerrit 82482 ovirt-4.1 MERGED spec: Require sanlock 3.5 on EL 2017-10-03 02:18 EDT

  None (edit)
Description nijin ashok 2017-08-02 13:19:08 EDT
Description of problem:

The sanlock initialization sometimes fails without any valid error messages in sanlock log or any exception message in the vdsm log.  

2017-07-24 14:56:32,958+0530 ERROR (tasks/3) [storage.Volume] Unexpected error (volume:1110)
Traceback (most recent call last):
  File "/usr/share/vdsm/storage/volume.py", line 1104, in create
    cls.newVolumeLease(metaId, sdUUID, volUUID)
  File "/usr/share/vdsm/storage/volume.py", line 1387, in newVolumeLease
    return cls.manifestClass.newVolumeLease(metaId, sdUUID, volUUID)
  File "/usr/share/vdsm/storage/blockVolume.py", line 319, in newVolumeLease
    sanlock.init_resource(sdUUID, volUUID, [(leasePath, leaseOffset)])
SanlockException: (-202, 'Sanlock resource init failure', 'Sanlock exception')
2017-07-24 14:56:32,958+0530 ERROR (tasks/3) [storage.Image] Unexpected error (image:892)
Traceback (most recent call last):
  File "/usr/share/vdsm/storage/image.py", line 882, in copyCollapsed
    srcVolUUID=sc.BLANK_UUID)
  File "/usr/share/vdsm/storage/sd.py", line 758, in createVolume
    initialSize=initialSize)
  File "/usr/share/vdsm/storage/volume.py", line 1112, in create
    (volUUID, e))
VolumeCreationError: Error creating a new volume: (u"Volume creation 5a9a3fb8-9560-4240-aadf-1d2536c8dfe1 failed: (-202, 'Sanlock resource init failure', 'Sanlock exception')",)

As per the vdsm log, this happens four times for the customer and two of them was while creating the OVF_STORE. There is nothing logged in the sanlock log regarding the error.  I am unable to find any reason why this is happening as logs don't have any info. May be we have to add new log entries in the related area to understand the root cause.


Version-Release number of selected component (if applicable):

vdsm-4.19.24-1.el7ev.x86_64
sanlock-3.4.0-1.el7.x86_64

How reproducible:

Rarely for the customer while creating the disks.

Actual results:

Sometimes disk creation fails with sanlock error

Expected results:

Disk creation should work.

Additional info:
Comment 2 Allon Mureinik 2017-08-03 03:48:22 EDT
I see a bunch of errors about storage connections timing out, and sanlock renewal failures (which makes sense given the connection timeout).

Nir - anything we can do from our end?
Comment 3 Nir Soffer 2017-08-03 14:56:42 EDT
(In reply to nijin ashok from comment #0)
> Description of problem:
> 
> The sanlock initialization sometimes fails without any valid error messages
> in sanlock log 

Initializing a volume lease is done using sanlock_direct_init - this is done
in the client caller process, so sanlock daemon does not know anything about it
and cannot log failures.

> or any exception message in the vdsm log.  
> 
> 2017-07-24 14:56:32,958+0530 ERROR (tasks/3) [storage.Volume] Unexpected
> error (volume:1110)
> Traceback (most recent call last):
>   File "/usr/share/vdsm/storage/volume.py", line 1104, in create
>     cls.newVolumeLease(metaId, sdUUID, volUUID)
>   File "/usr/share/vdsm/storage/volume.py", line 1387, in newVolumeLease
>     return cls.manifestClass.newVolumeLease(metaId, sdUUID, volUUID)
>   File "/usr/share/vdsm/storage/blockVolume.py", line 319, in newVolumeLease
>     sanlock.init_resource(sdUUID, volUUID, [(leasePath, leaseOffset)])
> SanlockException: (-202, 'Sanlock resource init failure', 'Sanlock
> exception')

This looks like an exception message to me.

Maybe you are referring to the unhelpful 'Sanlock exception' message? this was
fixed in sanlock 3.5.0, see:
https://pagure.io/sanlock/c/b79bd2ac317427908ced4834cc08a1198ce327a1?branch=master

Error -202 means:
$ git grep '\-202'
src/sanlock_rv.h:#define SANLK_AIO_TIMEOUT      -202

Which probably means that sanlock had a timeout accessing storage for
initializing a volume lease.
Comment 4 Nir Soffer 2017-08-03 14:58:10 EDT
David, do you think we can do anything here, or given the SANLK_AIO_TIMEOUT's and
renewal errors, this is a storage side issue that must be fixed by the system
admin?
Comment 5 David Teigland 2017-08-03 15:33:50 EDT
Initializing new lease areas doesn't retry on i/o timeouts, and I'm not sure that it should.  If you can't initialize leases without timeouts, it means that you probably need to fix the environment first.  i/o timeouts should not be a normal state on the system, and handling i/o timeouts is designed to allow the system (or storage) to be fixed gracefully.  I don't know what sort of advice we give admins about storage that times out.

That being said, we can of course improve the error messages to make clear what happened.  Just reporting -202 as an i/o timeout would probably help.

The recent improvements in error messages were limited because the project ended up being larger than expected.  The more significant improvements are still planned for the next release.
Comment 6 Nir Soffer 2017-08-03 15:43:21 EDT
With sanlock 3.5.0, this error will be reported as:

    SanlockException: (-202, 'Sanlock resource init failure', 'IO timeout')

I don't think there is anything to improve for this error.
Comment 13 Lukas Svaty 2017-08-28 02:21:05 EDT
Can you propose verification steps here?

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