The error logging daemon, syslogd, automatically records various system warnings and errors in message files. By default, many of these system messages are displayed on the system console and are stored in the /var/adm directory. You can direct where these messages are stored by setting up system message logging. For more information, see Customizing System Message Logging. These messages can alert you to system problems, such as a device that is about to fail.
The /var/adm directory contains several message files. The most recent messages are in /var/adm/messages file (and in messages.*), and the oldest are in the messages.3 file. After a period of time (usually every ten days), a new messages file is created. The messages.0 file is renamed messages.1, messages.1 is renamed messages.2, and messages.2 is renamed messages.3. The current /var/adm/messages.3 file is deleted.
Because the /var/adm directory stores large files containing messages, crash dumps, and other data, this directory can consume lots of disk space. To keep the /var/adm directory from growing too large, and to ensure that future crash dumps can be saved, you should remove unneeded files periodically. You can automate this task by using the crontab file. For more information about automating this task, see Removing Dump Files in Managing Devices in Oracle Solaris 11.3 and Chapter 4, Scheduling System Tasks in Managing System Information, Processes, and Performance in Oracle Solaris 11.3.