RHEL 4 - Memory Problem

Nuwan nrfromlk at gmail.com
Fri Mar 16 10:32:45 UTC 2007


Try the following ;

# dmesg | grep Memory:

Memory: 2071680k/2097088k available (1848k kernel code, 24692k
reserved, 752k data, 184k init, 0k highmem)

This will gave u enough understanding about the linux available memory !


On 3/16/07, baran.yurdagul at turkcell.com.tr
<baran.yurdagul at turkcell.com.tr> wrote:
> Hi,
> If you look at the free output you will see that altough 162M of your memory is free, the cached memory is  ~15GB which means kernel is ready for giving that area to any application that needs memory. Linux has allocated that memoy for some reason, and if it is needed it can give it back.
> I hope I am clear enough.
>
>
>
> -----Original Message-----
> From: redhat-list-bounces at redhat.com [mailto:redhat-list-bounces at redhat.com] On Behalf Of qua nong
> Sent: Friday, March 16, 2007 6:50 AM
> To: General Red Hat Linux discussion list
> Subject: Re: RHEL 4 - Memory Problem
>
> Hi,
>
> Below is the output of free
>
> # free
>             total               used           free         shared    buffers     cached
> Mem:      16360260   16197904     162356          0     256496   14974144
> -/+ buffers/cache:     967264   15392996
> Swap:     33551744     186960   33364784
>
> May I also ask you that as you mentioned that you run Oracle RAC on linux box. Do you use RHEL3 cluster or 4, GFS or OCFS ?
>
> Qua
>
>
> ----- Original Message ----
> From: Troy Knabe <knabe at 4j.lane.edu>
> To: General Red Hat Linux discussion list <redhat-list at redhat.com>
> Sent: Friday, March 16, 2007 3:20:02 PM
> Subject: Re: RHEL 4 - Memory Problem
>
> Try running the command "free"  I think, although I don't know why and would love for someone on this list to answer this question that this is a better actual representation of the free memory on the box.
>
> I am running the same config as you, only 3 boxes with 8 gig of RAM each and Oracle RAC.
>
> My hunch is that top and vmstat are showing the actual memory locations that are empty, where a "free" command shows the memory addresses that while may have something in them, are able to be recycled and used.
>
> Can someone verify that I am right or way off base?
>
> Thanks
> -Troy
>
>
> ----- Original Message -----
> From: qua nong <quanong_os at yahoo.com>
> Date: Thursday, March 15, 2007 9:02 pm
> Subject: RHEL 4 - Memory Problem
> To: redhat-list at redhat.com
>
> > Hi list,
> >
> > We have a AMD with RHEL4 64 installed and the Oracle 10g installed as
> > well.
> > It has  the latest kernel update 2.6.9-42.0.8.ELsmp but the memory is
> > always being used by some unexplained processes.
> >
> > There are 4 CPUs, 16 GB RAM, 33GB swap but memory used = 16148872k
> >
> > Even when oracle is shutdown, a memory use  is  still nearly 16GB. CPU
> > is 99.4 % in idle, and I/O is too quiet. This is quite difficult to
> > explain.
> >
> > Could anyone have any idea ?
> >
> > Here is the display of the top command
> >
> > top - 14:57:33 up 30 days, 22:29,  3 users,  load
> > average: 0.22, 0.10, 0.02
> > Tasks: 121 total,   1 running, 120
> > sleeping,   0 stopped,   0 zombie
> > Cpu(s):  0.0% us,  0.0% sy,  0.0% ni, 99.4% id,  0.6% wa,  0.0% hi,
> > 0.0% si
> > Mem:  16360260k total, 16198280k used,   161980k
> > free,   256496k buffers
> > Swap: 33551744k total,   186960k used, 33364784k free,
> > 14973940k cached
> >
> >  vmstat 2
> > procs -----------memory---------- ---swap-- -----io---- --system-
> > - ----cpu----
> >  r  b   swpd   free
> > buff  cache   si   so
> > bi    bo   in    cs us
> > sy id wa
> >  0  0 186960 161420 256496 14973940
> > 0    0     1
> > 112    3     1  0
> > 0 99  1
> >  0  0 186960 162284 256496 14973940
> > 0    0     0   170
> > 1021  2162  0  0 100  0
> >  0  0 186960 162276 256496 14973940
> > 0    0
> > 0    44 1009  2149  0  0 100  0
> >  0  0 186960 162284 256496 14973940
> > 0    0
> > 0    42 1008  2244  0  0 99  0
> >  0  0 186960 162292 256496 14973940
> > 0    0
> > 0    48 1011  2164  0  0 99  0
> >  0  0 186960 162292 256496 14973940
> > 0    0
> > 0    56 1006  2118  0  0 100  0
> >  0  0 186960 162292 256496 14973940
> > 0    0
> > 0    66 1011  2154  0  0 98  2
> >
> >
> >
> > cat /proc/meminfo
> > MemTotal:     16360260 kB
> > MemFree:        162740 kB
> > Buffers:        256496 kB
> > Cached:       14973940 kB
> > SwapCached:       9724 kB
> > Active:        2709340 kB
> > Inactive:     12799980 kB
> > HighTotal:           0 kB
> > HighFree:            0 kB
> > LowTotal:     16360260 kB
> > LowFree:        162740 kB
> > SwapTotal:    33551744 kB
> > SwapFree:     33364784 kB
> > Dirty:             332 kB
> > Writeback:         140 kB
> > Mapped:        1147256 kB
> > Slab:           608056 kB
> > CommitLimit:  41731872 kB
> > Committed_AS:  7853044 kB
> > PageTables:      39080 kB
> > VmallocTotal: 536870911 kB
> > VmallocUsed:     16760 kB
> > VmallocChunk: 536854071 kB
> > HugePages_Total:     0
> > HugePages_Free:      0
> > Hugepagesize:     2048 kB
> >
> >
> >
> >
> >
> >
> >
> >
> >
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>  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Troy Knabe
> Senior Systems Administrator
> Computing and Information Services
> 4J School District
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