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MQSeries.net Forum IndexGeneral IBM MQ Supportfilesystem data locks

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ammx
PostPosted: Tue Sep 19, 2017 4:09 pm Post subject: filesystem data locks Reply with quote

Newbie

Joined: 08 Sep 2017
Posts: 9

Hi

I am checking the qmgr error logs because my queue manager went down and I was searching for the cause of the problem. The error message is:

"AMQ7279: WebSphere MQ queue manager lost ownership of data lock.

The instance of the queue manager has lost ownership of a lock on its data in the filesystem due to transient failure. It was not able to reobtain the lock and will stop automatically to prevent the risk of data corruption".

I investigate a little bit about the filesystems that support reliable data locking and found that the NFS V4 is the one that supports file locking by a multi instance queue manager. I checked the filesystem where the qmgr is /var/mqm and the filesystem type is ext4, so I don't know if the filesystem supports this.
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Anant.v
PostPosted: Tue Sep 19, 2017 8:09 pm Post subject: Reply with quote

Apprentice

Joined: 26 Nov 2014
Posts: 35
Location: Malaysia

What does amqmfsck tells ?
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ammx
PostPosted: Wed Sep 20, 2017 12:02 pm Post subject: Reply with quote

Newbie

Joined: 08 Sep 2017
Posts: 9

When I am amqmfsck /var/mqm it throws me the following message:

The tests on the directory completed successfully.
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JosephGramig
PostPosted: Wed Sep 20, 2017 12:33 pm Post subject: Reply with quote

Grand Master

Joined: 09 Feb 2006
Posts: 1181
Location: Derby City, USA

Because you are using /var/mqm directory for your Qmgr, I would guess that you are not trying to use Multi Instance features. Right?

What version of the OS are you on?
What does dspmqinst say?
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ammx
PostPosted: Thu Sep 21, 2017 7:50 am Post subject: Reply with quote

Newbie

Joined: 08 Sep 2017
Posts: 9

It is a Linux RedHat 6, when I dspmqinst it shows the following:

InstName: Installation1
InstDesc:
Identifier: 1
InstPath: /opt/mqm
Version: 7.5.0.6
Primary: Yes
State: Available

so I guess I was wrong when I used the amqmfsck with the directory /var/mqm. But if I use the /opt directory it shows me an error message:

amqmfsck /opt/mqm

AMQ5667: Error executing system call 'open()' on file '/opt/mqm/amqmfsck.lck',
errno 13 ('Permission denied').

I know very little about Multi instance queue managers, so I am not sure how to troubleshoot this.

when I type dspmq to see the queue managers running on the server it only shows one active and another one which Ended unexpectedly, but there is no sign of another instance running as standby:

QMNAME(WCAPLQM3) STATUS(Running)
QMNAME(WCAPLQM1) STATUS(Ended unexpectedly)

But the error message makes me think that there is multi-instance configuration running in the server:

"The instance of queue manager WCAPLQM3 has lost ownership of a lock on its data in the filesystem due to a transient failure. It was not able to reobtain the lock and will stop automatically to prevent the risk of data corruption.

Check that another instance of the queue manager has become active. Restart this instance of the queue manager as a standby instance. If this problem recurs, it may indicate that the filesystem is not sufficiently reliable to support file locking by a multi-instance queue manager"

If I type mqsilist to list the brokers running I get the following:

BIP1295I: Integration node 'WCAPLBK3' is an active multi-instance or High Availability integration node that is running on queue manager 'WCAPLQM3'.
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JosephGramig
PostPosted: Thu Sep 21, 2017 8:25 am Post subject: Reply with quote

Grand Master

Joined: 09 Feb 2006
Posts: 1181
Location: Derby City, USA

mqsilist always gives that answer if you created the Integration Node (broker) with the -e switch to put the Integration Node in a non default path (which is what you need to do when it is HA or MI).

dspmqinf WCAPLQM1

Should display where MQ expects the Qmgr to be located. If this is MI, then it will say where the MI NSFv4 mount point is located.

If this is a MI Qmgr, then you need to know where the "Standby" is/was running.

You need to know a lot. You should seek experienced help from some one on your team. If you have no resources like that at your company, IBM would be happy to sell you some services that will get you up to speed.

When working with MI Qmgr and you want to see the status, use:

dspmq -x
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ammx
PostPosted: Thu Sep 21, 2017 1:25 pm Post subject: Reply with quote

Newbie

Joined: 08 Sep 2017
Posts: 9

Hi

With this command I checked the path of the qmgr:

dspmqinf -o command WCAPLQM1, and it gave me this information:

addmqinf -s QueueManager -v Name=WCAPLQM1 -v Directory=WCAPLQM1 -v Prefix=/var/mqm -v DataPath=/HA1/MQ/qmgrs/WCAPLQM1

with this path I can check the shared filesystem type to see if it supports the data locks

df -P -T /HA1/MQ/qmgrs/WCAPLQM1 | tail -n +2 | awk '{print $2}'

and it throws me this result:

gpfs

It is a cluster filesystem and when I make the test with amqmfsck /HA1/MQ/qmgrs/WCAPLQM1 it says everything is fine.

"The tests on the directory completed successfully."

I need to perform other two tests in both servers, but I don't know in which other server is the other instance located

amqmfsck -c <directoryName> and amqmfsck -w <directoryName>
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