When going through my emails that are produced by the cron jobs ran on my Solaris servers, I am receiving a message that states,"/ is 50% full" what can I do to either lower the amount of data on this partition or raise the threshold limits to to stop this message? I would prefer to learn how to lower the amount of data on this disk to bring under my disk quota of 50% in order to stop these emails being produced by the cron job running on this server, thank you.

"quota" has a specific meaning in Linux/UNIX. What you are talking about is not "quota" but rather "utilization".

Typically to see what is using up space in a filesystem you can do:

cd /
"du -sk * |sort -n"

That will show what is using up the most space at the bottom of the list it produces, then the next most, then the next most etc... You can then drill down in each successive directory (e.g. /usr, /etc, /opt, /home).

Of course you may have filesystems mounted on / (on many systems /usr, /opt, /tmp and /home are often separate filesystems. If so the space they use is NOT part of what is taking up your 50% in / so can be ignored for what you are searching for.

Often it is worthwhile to look for "core" files on your system as generally these are memory dumps of processes that died and are often quite large. You can do "find / -name core" to find any of those. If you run "file" command on any of the cores you find you can verify it is a core dump file. (You need to run "file" because some applications like Oracle actually create directories or files named core that are not core dumps and you do NOT want to delete those.)

Additionally you could look for any file ending in ".tar". These are tar archive files and often are put on your system when you are installing some new package manually or copying files from one system to another or even just making a local backup of a directory before doing maintenance on it. Often these can be deleted or at least gzipped to reduce the space they take up. Running "tar tvf <tarfile>" against any tar you find will show you what it is in the archive. (You find them with 'find / -name "*.tar"'.)

Often you will see log files of one sort or another growing forever so truncating or deleting those may free up space. Before doing that to any log though run "lsof" against the log to be sure it is not currently being held open by any process. Deleting files held open does not really delete them - it gets rid of the name but the data is still in the inode. Often you have to stop the application that holds the file open then clean up the file then restart the application.

To change the threshold of the check you'd have to find what cron job is issuing the message about 50% then modify the underlying application (usually a script) to change the threshold. Personally I think 50% is too low a threshold unless you're on a system that has rapid and sudden growth of files in / filesystem which should not be the case unless you have everything in a single filesystem.