topic memory sizing methodology ? in Operating System - Linux

memory sizing methodology ?

Thomas Ritter — Thu, 27 Nov 2008 04:59:19 GMT

Given that linux tries to use all available memory and monitoring tools show near if not 100% memory utilisation, what approaches do system managers take to ensure memory shortages do not occur ?
In my view, not familair with linux, I would try an build a model show the number of process and their average working set and take this is the minimum memory required.

Would someone like to share the memory sizing methodologies ?

Re: memory sizing methodology ?

Prasu — Thu, 27 Nov 2008 11:31:09 GMT

Yes Thomas ...

You are correct .. i think linux will use the physical memory as a file system cash & it will keep most freequently used files in ths memory.

I had instlled one tool NMON, i think that will show it seperatly

Regards
Prasu

Re: memory sizing methodology ?

Prasu — Thu, 27 Nov 2008 12:21:13 GMT

You can use this tool to view system performance ,...

Its a very cool one

http://www.ibm.com/developerworks/wikis/display/WikiPtype/nmon

Regards
Prasu

Re: memory sizing methodology ?

Ben Stokes — Thu, 27 Nov 2008 13:31:30 GMT

I use cacti and this template to monitor memory usage:

http://forums.cacti.net/about11376.html

As you mentioned, other tools can show 100% of memory in use where this template can tell you where the memory is used. You can also configure alerting if there is no cache memory available or too much swap in use.

Re: memory sizing methodology ?

Ivan Ferreira — Thu, 27 Nov 2008 14:28:49 GMT

>>> what approaches do system managers take to ensure memory shortages do not occur ?

Use the free command to identify the real memory usage, without the buffers and the cache.

Use the vmstat command to identify page in and page outs. If so, then you have memory shortage.

This is not sizing, this is monitoring. If you want to do some sizing, that is, predict how much memory (or other resources) you will need in the future, it depends of what is doing your server.