Guidelines for configuring /swap partitions

Admittedly, I am new to Linux, however I am a decades old UNIX
administrator. I ask patience if my question seems beneath this group.

I have a production server with 12 gig of ram, running Inetd daemons for
high volume, short duration IP transactions, often times less than 4
seconds. I am using RedHat Enterprise, version 10, and it recommends a
max of 2 gig for swap space, a mere portion of available user memory.

Is this 2 gig limit real, or based on specifications of older hardware
supporting lower amounts of system memory?

For that matter, is my production too large for Linux?

Joseph

In article <u8hAd.28$JC2.10@newsread2.news.atl.earthlink.net> ,
Joseph Dionne wrote:

>Admittedly, I am new to Linux, however I am a decades old UNIX
>administrator. I ask patience if my question seems beneath this group.

So you know about 'top' and 'free' and how to determine what is
swapped out using the 'ps' command.

>I have a production server with 12 gig of ram, running Inetd daemons for
> high volume, short duration IP transactions, often times less than 4
>seconds. I am using RedHat Enterprise, version 10, and it recommends a
>max of 2 gig for swap space, a mere portion of available user memory.

OK, the assumption is you are also using the big-memory kernel too.

>Is this 2 gig limit real, or based on specifications of older hardware
>supporting lower amounts of system memory?

Do you really _need_ that much swap? Normally, with that much memory,
the system shouldm't be using much (if any) swap space. With our systems
that at work stations and relatively dumb servers, we tend to have lots
of stuff cached and/or buffered, and there might be ten or twenty Megs
of unused stuff swapped out, and that's it.

>For that matter, is my production too large for Linux?

Dunno - what does 'free' show?

Old guy

Moe Trin wrote:
> In article <u8hAd.28$JC2.10@newsread2.news.atl.earthlink.net> ,
> Joseph Dionne wrote:
>
>
>>Admittedly, I am new to Linux, however I am a decades old UNIX
>>administrator. I ask patience if my question seems beneath this group.
>
>
> So you know about 'top' and 'free' and how to determine what is
> swapped out using the 'ps' command.
>
>
>>I have a production server with 12 gig of ram, running Inetd daemons for
>> high volume, short duration IP transactions, often times less than 4
>>seconds. I am using RedHat Enterprise, version 10, and it recommends a
>>max of 2 gig for swap space, a mere portion of available user memory.
>
>
> OK, the assumption is you are also using the big-memory kernel too.
>
>
>>Is this 2 gig limit real, or based on specifications of older hardware
>>supporting lower amounts of system memory?
>
>
> Do you really _need_ that much swap? Normally, with that much memory,
> the system shouldm't be using much (if any) swap space. With our systems
> that at work stations and relatively dumb servers, we tend to have lots
> of stuff cached and/or buffered, and there might be ten or twenty Megs
> of unused stuff swapped out, and that's it.
>
>
>>For that matter, is my production too large for Linux?
>
>
> Dunno - what does 'free' show?
>
> Old guy

Thanks for your response, but continued research lead me to a answer.

Yes, "hugemem" is being used. No, the server is not swapping now but
this will be a DB server and with anticipated loads, swapping is
expected as its data/isam buffers increase.

The point of the post was advice on best use of swap space under linux.
Since this post I am modeling worse case swap configurations, most for
our front line servers that will be hosting thousands of client app
processes. I believe a larger number of swap fs that are small in size
on their own physical device will be most effective to keep performance
up until mew front line servers are added to the farms.