HPUX server failed to alert for Swap memory

book

Article ID: 221491

calendar_today

Updated On:

Products

DX Infrastructure Management

Issue/Introduction

There was an issue where  swap memory uage was 100% but in UIM it was showing as 1.9% and failed to trigger alert.

Output from server

Command:- /usr/sbin/swapinfo

Sat Jun 26 01:32:58 EDT 2021

                 Mb          Mb           Mb   PCT      START/          Mb

TYPE          AVAIL        USED         FREE  USED       LIMIT     RESERVE  PRI  NAME

dev           32768         626        32142    2%           0           -    1  /dev/vg00/swap_primary

reserve           -       32140       -32140

memory  31161       31124           37  100%

total         63929       63890           39  100%       -           0    -

Environment

Release : 20.3

Component : UIM - CDM WITH IOSTAT

Resolution

The probe is using pstat_getswap() API which will calculate swap memory for device and file system but not "reserve" and "memory" as shown in the swapinfo command output.

From the command output, "memory" is nothing but a Pseudo swap. It is a swap space, which the operating system recognizes, but in reality it does not exist. It does not exist in memory; it does not exist on disk; it does not exist anywhere. However, the operating system does recognize it, which means more swap space can be reserved than physically exists. The purpose of pseudo swap is to allow more processes to run in memory, than could be supported by the swap device (dev and filesystem).

Here the actual swap memory is dev and filesystem only, that is the reason the probe is not considered reserve and memory data while calculating the swap memory. So probe is working as expected.

 

Please refer the below article which will explain in detail about the swap memory (swapinfo command).

https://brainscraps.fandom.com/wiki/Understanding_Device_and_Pseudo_Swap

 

thanks,