VNX: Control Station (CS) Memory Utilization is High

* Running "top" and "free -m" commands on the Control Station shows the used  memory is 90%+

$ top

top - 11:27:10 up 5 days, 15:57,  1 user,  load average: 0.10, 0.21, 0.28
Mem:   2071700k total,  1935556k used,   136144k free,   493100k buffers
Swap:  2096440k total,      108k used,  2096332k free,   820184k cached


 $ free -m
             total       used       free     shared    buffers     cached
Mem:          2023       1890        132          0        481        800
Swap:         2047          0       2047  

* Running "top" command shows no process consumes the memory and load average is low "Less than 1".

* Used "Swap" is almost 0.

* Control station performance is normal, even the memory usage is 90%+.

* Monitoring systems keep alerting the customer with abnormal Memory usage.

* Control Station reboot reduce the used memory, but after a while it starts increasing again.

This is normal and works as designed.

Control Station OE is based on Linux, Linux always tries to use RAM to speed up disk operations by using available memory for buffers (file system metadata) and cache (pages with actual contents of files or block devices). This helps the system to run faster because disk information is already in memory which saves I/O operations.

If space is needed by programs or applications like Oracle, then Linux will free up the buffers and cache to yield memory for the applications. If your system runs for a while you will usually see a small number under the field "free" on the first line.

This is a normal situation and need no action as long as:

1- No process consumes the memory "Check using top command".
2- Load average is low "Check using top command, less than 1".
3- Used "Swap" is almost 0 "Check using top command and free -m".
4- Control Station performance is normal.
5 - buffers and cache consumes most of Memory used space "Check using top command and free -m":

$top
top - 11:27:10 up 5 days, 15:57,  1 user,  load average: 0.10, 0.21, 0.28
Mem:   2071700k total,  1935556k used,   136144k free,   493100k buffers
Swap:  2096440k total,      108k used,  2096332k free,   820184k cached


 $ free -m
             total       used       free     shared    buffers     cached
Mem:          2023       1890        132          0        481        800
-/+ buffers/cache:        607       1415
Swap:         2047          0       2047