Creating file systems on Linux
Before installing IBM® MQ, you might need to create file systems for both the product code and working data to be stored. There are minimum storage requirements for these file systems. The default installation directory for the product code can be changed at installation time, but the working data location cannot be changed.
Determining the size of a server installations file system
- The maximum number of messages in the system at one time.
- Contingency for message buildups, if there is a system problem.
- The average size of the message data, plus 500 bytes for the message header.
- The number of queues.
- The size of log files and error messages.
- The amount of trace that is written to the /var/mqm/trace directory.
Creating a file system for the working data
Before you install IBM MQ, create and mount a file
system called /var/mqm which is owned by the user
mqm in the
mqm ; see Setting up the user and group on Linux. This file system is used by all
installations of IBM MQ on a system. If possible, use a
partition strategy with a separate volume for the IBM MQ
data. This means that other system activity is not affected if a large amount of IBM MQ work builds up. Configure the directory permissions to
mqm user to have full control, for example, file mode 755. These
permissions will then be updated during the IBM MQ
installation to match the permissions required by the queue manager.
Creating separate file systems for errors and logs
You can also create separate file systems for your log data ( /var/mqm/log ) and error files ( /var/mqm/errors ). If possible, place these directories on different physical disks from the queue manager data ( /var/mqm/qmgrs ) and from each other.
If you create separate file systems the /var/mqm/errors directory can be NFS mounted. However, if you choose to NFS-mount /var/mqm/errors, the error logs might be lost if the network fails.
In the rare event that you need to trace an IBM MQ system for problem determination, you can reduce performance impact by placing the /var/mqm/trace file system on a separate disk.
If you are creating separate file systems, allow a minimum of 30 MB of storage for
/var/mqm, 100 MB of storage for
/var/mqm/log, and 10 MB of storage
/var/mqm/errors. The 100 MB minimum allowance of storage for
/var/mqm/log is the absolute minimum required for a single queue manager and is not
a recommended value. The size of a file system must be scaled according to the number of queue
managers that you intend to use, the number of pages per log file, and the number of log files per
For more information about file systems, see File system support.
The size of the log file depends on the log settings that you use. The minimum sizes are for circular logging using the default settings. For more information about log sizes, see Calculating the size of the log.
- For a client installation, the file system can be mounted on a remote network device, for example NFS.
- If you are performing both a client and a server installation, the requirements of the server installation take precedence over the requirements of the client installation.
- Allow 15 MB as a minimum for an IBM MQ client.
- A new sample IBM MQ MQI client configuration file is
created in the var/mqm directory, by the client package, during installation,
but only if this file does not exist. This file contains the
ClientExitPathstanza. An example mqclient.ini file is shown in Configuring a client using a configuration file.
- If you are using a common configuration file for multiple clients, either in the IBM MQ installation directory or in another location using the MQCLNTCF environment variable, you must grant read access to all user identifiers under which the IBM MQ client applications run. If, for any reason, the file cannot be read the failure is traced, and the search logic continues as if the file had not existed.