WHY is the SWAP memory increasing on our gateway appliance

Products

• CA API Gateway

Issue/Introduction

AppD reporting gateway JVM memory hitting 80%.  The SWAP memory increase during this timeframe going to 70 % usage 

Why is SWAP being used ?

Environment

Gateway 11.1.1

Cause

The default setting for swappiness in the OVA and must linux systems is = 60.  

This value means that the swap file will be used fairly often if the memory usage above 60 (over half of the system memory)

AppD shows Gateway are hitting 60 - 80% - the kernel will move memory to SWAP at times, NOTE there is no system/memory manager for this space it will not recover unless the specific APP using swap is restarted or the system rebooted 

 

Resolution

Swappiness setting of zero means that the disk will be avoided unless absolutely necessary (you run out of memory), while a swappiness setting of 100 means that programs will be swapped to disk almost instantly.

The default GW OVA configured with swappiness of 60

# cat /proc/sys/vm/swappiness

60

#  sysctl vm.swappiness

vm.swappiness = 60

Set SWAPPINESS to 10 to limit it’s usage for GW App

# sysctl vm.swappiness=10

OR disable SWAP 

# sysctl vm.swappiness=0