FW: [olug] Possible error message

Vincent vincentr at cox.net
Wed May 7 21:53:57 UTC 2003


Try sar (if you have it setup).  It should be more comprehensive.  Free only tells you what's happening right now and has no memory
of the past.

sar -r | egrep swp\|Average

----- Original Message ----- 
From: "Brian Wiese" <bwiese at cotse.com>
To: "Omaha Linux User Group" <olug at olug.org>
Sent: Wednesday, May 07, 2003 4:26 PM
Subject: Re: FW: [olug] Possible error message


> Good point, might want to periodically check the swap freespace in
> megabytes (free -m) to find out if it is ever being used.  Is this an
> accurate way to measure it's use?
>
> On Tue, 06 May 2003 21:14:48 -0500
> Phil Brutsche <phil at brutsche.us> wrote:
>
> |Trent Melcher wrote:
> |>
> |> -----Original Message-----
> |> From: Trent Melcher [mailto:tmelcher at trilogytel.com]
> |> Sent: Tuesday, May 06, 2003 8:26 PM
> |> To: 'CM Miller'
> |> Subject: RE: [olug] Possible error message
> |>
> |>
> |> Yes, the gerenal rule of thumb is usually double the amount of RAM you
> |> have for swap.
> |
> |That's an old rule of thumb that really doesn't necessarily apply to
> |modern systems.  VM subsystems have improved quite a bit since the 1980s
> |:)
> |
> |Does a Linux firewall with 32 MB - one that's not running squid :) -
> |REALLY need ANY swap, much less 64MB?  NO
> |
> |Does that database server with 2GB RAM REALLY need that 4GB swap?  Well,
> |maybe it does...
> |
> |Does a workstation (ie MINE!) with 1GB+ RAM REALLY need 2GB+ swap?  NO
> |
> |Does having swap help performance?  YES (at least, I've heard it does
> |under Linux, I've never run without swap to find out)
> |
> |YMMV, of course.  It all depends on the situation, and most of the ones
> |I run into you do NOT *need* 2x RAM for swap.  99% of the time it's too
> |much for the application (ie it's wasted disk space because it's never
> |used), and the rest of the time it's way too little (mostly because the
> |machine's owner doesn't want to spend the $35 to get that extra Crucial
> |256MB DDR266).
> |
> |> I cant remember exactly, but there is a 4 GB limitation for 32bit
> |> processors, it either on physical RAM or Virtual RAM, it may be both,
> |> havent looked it up in a while.
> |
> |Without PAE, 4GB physical; 36GB physical with PAE.  PAE is this feature
> |on PPro (maybe PII) and newer CPUs that changes memory addressing a
> |little bit (36-bit addresses instead of 32-bit).
> |
> |64GB total available address space.
> |
> |That's with 32-bit ix86 processors, of course :)
> |
> |-- 
> |
> |Phil Brutsche
> |phil at brutsche.us
> |
> |
> |_______________________________________________
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> |OLUG at olug.org
> |http://lists.olug.org/mailman/listinfo/olug
> |
>
>
>   Brian Wiese | bwiese at cotse.com | aim: unolinuxguru
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