When a file system runs out of free space, it leads to numerous system and application failures. When the file system gets full, you might experience the following system issues:
Degradation in performance
Difficulty in spotting unused blocks by the kernel to store new data
System hangs due to long response time
The threshold when the effects on the system becomes visible varies from one file system to another. As a best practice, always keep the file system space usage below 90%.
Oracle Solaris provides the following standard UNIX tools to monitor file system space usage:
Displays the number of used blocks, number of free blocks, and calculates total file system space usage in percentage.
Displays the number of blocks a file or a set of files occupies.