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Top Forums UNIX for Advanced & Expert Users linux memory buffers & cache usage Post 302487859 by drummerrob on Thursday 13th of January 2011 08:54:35 PM
Old 01-13-2011
linux memory buffers & cache usage

Code:
18:45:47 # free -m
             total       used       free     shared    buffers     cached
Mem:         96679      95909        770          0       1530      19550
-/+ buffers/cache:      74828      21851
Swap:        12287        652      11635

Hi all. The below output is from a RHEL 4.5 node running a single Oracle instance. I am looking to increase the SGA shortly and am curious about the effects given the current utilization information above. I understand that this system has 770mb of "free" memory and roughly 20gb allocated in buffers & cache. My question is, if I were to increase the SGA by about 4gb, this would take away from available memory that
can be used for buffers and cache, do i run a risk of having some IO issues given the amount of cache that i am currently usiing?

Thank you in advance for any feedback you can provide!


Moderator's Comments:
Mod Comment Please use code tags when posting data and code samples!

Last edited by Franklin52; 01-14-2011 at 05:33 AM..
 

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FREE(1) 							Linux User's Manual							   FREE(1)

NAME
free - display information about free and used memory on the system SYNOPSIS
free [-b|-k|-m|-g] [-l] [-o] [-t] [-s delay ] [-c count ] DESCRIPTION
free(1) displays the total amount of free and used physical memory and swap space in the system, as well as the buffers and cache consumed by the kernel. OPTIONS
Normal invocation of free(1) does not require any options. The output, however, can be fine-tuned by specifying one or more of the follow- ing flags: -b, --bytes Display output in bytes. -k, --kb Display output in kilobytes (KB). This is the default. -m, --mb Display output in megabytes (MB). -g, --gb Display output in gigabytes (GB). -l, --lowhigh Display detailed information about low vs. high memory usage. -o, --old Use old format. Specifically, do not display -/+ buffers/cache. -t, --total Display total summary for physical memory + swap space. -c n, --count=n Display statistics n times, then exit. Used in conjunction with the -s flag. Default is to display only once, unless -s was speci- fied, in which case default is to repeat until interrupted. -s n, --repeat=n Repeat, pausing every n seconds in-between. -V, --version Display version information and exit. --help Display usage information and exit FILES
/proc/meminfo -- memory information SEE ALSO
ps(1), top(1), vmstat(1) AUTHORS
Written by Robert Love. The procps package is maintained by Rik van Riel and Robert Love and was created by Michael Johnson. Send bug reports to <procps-list@redhat.com>. Linux 18 Nov 2002 FREE(1)
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