Re: RHEL memory questions

From: Mark Brinsmead <mark.brinsmead_at_gmail.com>
Date: Thu, 1 Oct 2015 23:03:57 -0600
Message-ID: <CAAaXtLDw9wi77s0qVt05GXVXckJTiuxS2hwHKrNiy3HUpAZQyQ_at_mail.gmail.com>

On most Linux (Unix) systems, it is completely normal to see memory is roughly 100% utilized, unless the system is sitting idle.

Any memory not used by your applications is usually taken by the operating system for filesystem buffers.

Seeing memory at or near 100% (total) utilization is not necessarily an indication of a problem. Nor is it necessarily an indication that the memory is being used effectively. (On an Oracle database server, memory is usually put to better use in your SGA and PGA than in filesystem buffers.)

There are others here who can -- I am sure -- answer much more precisely than I have, so I'll go back to lurking now.

Cheers!

On Wed, Sep 30, 2015 at 5:53 PM, David Ramírez Reyes <dramirezr_at_gmail.com> wrote:

> Hello List!
>
>
>
> Am just starting working with Oracle (11g R2) over RHEL(5) and I have some
> basic doubts that I would like to clarify (until now, I’ve been working
> with Oracle over Windows):
>
>
>
> - As part of a daily DB report, I need to check the memory usage
> of the server and am getting these:
>
> total used free shared buffers cached
>
> Mem: 62 61 1 0 1 55
>
> -/+ buffers/cache: 4 58
>
> Swap: 31 0 31
>
> Total: 94 61 33
>
>
>
> As you can see, “free” memory is almost over (although there’s no swap)
> which makes me report that memory usage is at 98% (it sounds strange to
> me), is this a normal behavior?; I’ve checked the processes running and
> there’s no a pick process but many opened by the oracle connections to the
> DB; depending on the answer, the next questions would be if more memory is
> required or if there’s a way to limit the memory that Oracle uses (on
> Windows, there’s a single Oracle process –with all subprocesses inside- and
> is very easy to determine and restrict the memory used by the DB, here in
> Linux seems like I need to sum the memory used by all processes for oracle
> user and seems not easy to restrict to a limit, is this correct?).
>
>
>
> Any advice, tip or trick for an Oracle DBA over Linux is well received.
>
>
>
> Thanks
>
>
> David Ramírez Reyes
> Profesión: Padre de Familia
>
>
>
>
>

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Received on Fri Oct 02 2015 - 07:03:57 CEST