Swap memory usage is high in Linux

 
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Operating Systems Linux Red Hat Swap memory usage is high in Linux
# 1  
Old 01-25-2015
Swap memory usage is high in Linux

Hi ,

There is one following alert .

Message : cdm:Average (2 samples) swap memory usage is now 91%, which is above the warning threshold (90%)

Here is my findings.

Output of TOP command in Linux server.

Code:
top - 14:21:44 up 6 days,  4:48,  1 user,  load average: 2.55, 2.06, 1.99
  Tasks: 495 total,   3 running, 492 sleeping,   0 stopped,   0 zombie
  Cpu(s):  5.3%us,  0.6%sy,  0.0%ni, 93.0%id,  0.8%wa,  0.0%hi,  0.3%si,  0.0%st
  Mem:  49454056k total, 49184128k used,   269928k free,    92960k buffers
  Swap: 16777208k total, 15902972k used,   874236k free, 45983512k cached

Code:
[oracle@server20 ~]$ vmstat 4 5
  procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu------
  r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
  0  0 15903124 265780  92988 45987776    0    2  2606   216    2    1  5  1 93  1  0
  0  0 15903124 269848  93028 45984436    0    0 36708   299 2885 10146  1  2 96  1  0
  0  0 15903124 268988  93100 45985100    0    0  3924   244 1481 9375  1  1 98  0  0
  0  0 15903124 269884  93088 45985180    0    0 52223    44 3446 9826  1  1 97  1  0
  1  0 15903124 270236  93024 45984104    0    0 86088   133 5065 10756  1  2 96  1  0


OS - Linux 5.11

This is 2 node cluster with one DB is running.

Please suggest me how to reduce swap usage in linux ?

Regards,
Maddy
# 2  
Old 01-25-2015
The propensity of the Linux kernel to swap out is determined by the value in the file /proc/sys/vm/swappiness

You can modify by running the following (10 is the recommended value by Oracle for DB servers)
Code:
sysctl -w vm.swappiness=10

This User Gave Thanks to Skrynesaver For This Post:
# 3  
Old 01-25-2015
Oracle also has a "unique" feature - when an SGA is allocated in shared memory, a backing store (identical size) is created in swap. This assures virtual memory availability later on. You create an 11GB SGA you also consume 11GB of swap.
This User Gave Thanks to jim mcnamara For This Post:
# 4  
Old 01-30-2015
Thanks all.
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