Possible Causes:

-    Tablespace Full
-    The db2diag.log too big
-    Transaction log full
-    User’s file too big

Investigation:

Step 1: Check File System Utilization:

df –k | grep -i <fsname>

Filesystem    1024-blocks      Free %Used    Iused %Iused Mounted on
/dev/hd4           229376    115676   90%     9211     9% /home/db2inst1

Step 2: on file system path, List the biggest files

du –k | sort +10

Resolution:

Compress files:

compress <filename> 
     
or

gzip <filename>

Send files to TSM :

dsmc incremental <filename>

Remove files:

rm –rf filename

Please make sure you are not touching files that are being used like, file containers, primary and secondary log files.

Usually we work with db2 dump files ( db2diag.log and etc), if you don’t have TSM on the server try to move the files to other file system, you can also involve aix and app team to discuss what is the best solution for the problem.