Re: adding more ram

From: Robert Watson (rwatson_at_freebsd.org)
Date: 12/11/03

  • Next message: David Schultz: "Re: adding more ram" 
    Date: Thu, 11 Dec 2003 00:01:20 -0500 (EST)
To: Dan Nelson <dnelson@allantgroup.com>

    On Wed, 10 Dec 2003, Dan Nelson wrote:

    > In the last episode (Dec 10), nbari@unixmexico.com said:
    > > I have a server with 1GB of RAM and a swap partition of 2GB i will
    > > upgrade the memory server to 2GB so my questions are:
    > >
    > > should i fix the swap partition to have now 4GB of space ?
    >
    > Depends. Have you ever used up that 2gb of swap? If not, you'll
    > probably never consume 4gb either :) If this is a database server, or
    > something similar where a few processes allocate large amounts of
    > memory, you don't need much swap anyway, since if any of those processes
    > actually has to swap, you end up thrashing the system as it tries to
    > swap 500mb processes in and out of memory. I really can't think of a
    > system that would still perform well with 2 or 3GB of process space in
    > swap. At the 2gb RAM point, you usually have a system where any
    > swapping == bad news.

    Actually, the thing I use swap for most now is to make sure I can allocate
    large temporary file systems without consuming excessive kernel address
    space. I.e., I'll often create a 512mb swap-backed md device for /tmp,
    and make sure I have enough swap to fully back it and everything else,
    even though the chances are I won't touch it in normal operation. I just
    don't want to run out in the event something does need it...

    Robert N M Watson FreeBSD Core Team, TrustedBSD Projects
    robert@fledge.watson.org Senior Research Scientist, McAfee Research

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  • Next message: David Schultz: "Re: adding more ram"

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