How to analyse Swap/Memory usage Oracle Solaris?

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Oracle Solaris MemoryMemory bottlenecks are evidenced by two different things happening on the system.

  • Paging
    • Page in;something is moved into Active RAM whether that is from Inactive RAM, the swapfile(s), or another file on the hard drive.
      • Page out;anything is moved out from Active RAM to Inactive RAM, as well as writing to a Swapfile. Also in some cases, high  page  out means your system has run out of memory and had to use some of the Hard Disk instead of RAM.
  • Swapping

Paging refers to memory pages being reclaimed by the system page daemon, when system faces with lack of free memory.Swapping is more extreme and it means that processed being swapped out. Determine if system is only paging or swapping you should check two columns in “vmstat” output. The first result you need to check is “scan rate (sc)”.If this result is different from “0” then it means page daemon scans for free memory pages to put in them on the free list to be reused.

Page scan runs: default value is 1/64th of total physical memory or cache free.

Don’t worry about high scan rate if you are using the file system heavily. If priority_paging is enable high scan rate can be normal in many circumstances. If priority_paging is enabled then page scanners daemon steals pages more effectively. So the file system I/O does not cause unnecessary paging of process.

Check “w” column to see if system is swapping. It shows entire processes which are swapped out. If “w” column is different from 0, system is either low on memory right now, or have been in the past.

Use this command to see which processes are running .Don’t forget that check for RSS column if it’s 0 (sched, pageout and fsflush processes should always have a RSS of 0). If not then it means that system is swapping out.


Scan Rate And “w” Column:

RSS  check: RSS  column must be “0”  for this check.If not system is low on memory right now.

Page Out, Page in:

Check Free Memory: 

How to calculate  sar free memory  usage?

 
Parameter Size Total Free  Size
Free Mem GB Free  Memory*8  /1024/1024/1024
Free Swap GB Free  Swap * 512 /1024 /1024/1024

Pagesize for Oracle  Solaris  is  8K.
How to check  page size  on Oracle Solaris ?

How to check free  memory  on Oracle  Solaris?

How  to check process  memory  usage  on Oracle Solaris?

This  command will sort  processes  by memory usage(RSS ).If you need change sort  option for  Virtual Size.

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Abdurrahim

I'm a System Engineer with extensive experience and administration skills and works for Interbank Card Center Of Turkey.I provide hardware and software support for the following Unix/Linux and Windows platforms.(Oracle Solaris,HP-UX, Linux, IBM-AIX, Windows Servers)
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