Why mq ffdc logs are piling up ?

We observed in our environment MQ /var/mqm file system is getting full and got filesystem alert . We cleared the logs and within 2 min filesystem is again full . We see the ffdc files are generating .

AMQ6119 with rc=27 meaning EFBIG “File too big” on both Sending and Receiving queue managers. Probe ID AD020000 is caused by an attempt to increase the queue file size beyond the Operating System limit (ulimit).

When we look in the QMGR actually the SDR channel is down and the Transmit queue is holding lot of message that actually reach the max size of the file that can hold the data as per the mqm user limits . Configured value for max size of a file is 2 GB as it reaches that then the file is unable to grow and MQ is throuing exception on ffdc.

We reset and start the channel then the message processed and stops writing the ffdc .

How to reset channel

stop channel(channel_name)

reset channel(channel_name)

stop channel(channel_name)

MQ supports queues larger than 2 GB. However, on AIX and Linux systems, you need to explicitly enable large file support before you can create queue files larger than 2 GB.

So, in order to resolve the issue, you need to Increase the /etc/security/limits to go beyond 1GB. You may refer your operating system documentation for information on how to do this.

Three things have to occur to over come the limit:

1. Enable large file support.

2. Increase the ulimit values to match the MQ limit or to unlimited.

3. Delete and re-create the queue PLBFMAPOR81.QM1 after you have enabled large file support.

So, please enable large file support and increase the ulimit as desired to stop the FDCs.

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