On Tue, 3 Oct 2000, guy keren wrote:
>
> On Tue, 3 Oct 2000, Dani Arbel wrote:
>
> > i would reccomand to make the swap at least double the RAM size. that
> > system has too small swap partition.
>
> sorry for poking in again - i just had to dispell that mith. this 'swap
> size is double RAM size' was the rule of thumb for unix administrators
> about 5-10 years back. unix systems back then used to pre-allocate space
> in the swap partition for every page of memory allocated for program's
> code and data segments in memory. this meant that you had tohave at least
> the same ammount of swap space as your RAM size, in order to be able to
> use all of your system's RAM.
Actually, what you are describing is the BSD 4.n (n<=3) behaviour (SunOS
4 is based on BSD4.3). SysV always used swap and RAM to store pages (Irix
3.3 (SysVR3), AIX 3.1 are two SysV OSes that were in use ten years ago and
used the 'new' model). In BSD 4.4 (which FreeBSD 2.x and above is based
on) this is no longer true.
> also, RAM was very expensive back then, so it was scarce.
>
> these days, however, RAM is cheap, and linux does not do that
> pre-allocation (and i think neither do other modern unices), so some
> people manage to run their machine without using any RAM at all. if you
> system starts using swap space alot - it's often cheap enough to simply
> buy more ram. using a lot of swap is mostly leftrelevant for heavy-duty
> machi, and even then you try to get your system to do as little swap as
> possible (especially if you're running an interactive web server, or
> similar).
You ment '... run their machine without using any swap at all.'. That's
true. It is unlikely that if your machine has 0.5Gb of RAM you will
install 1Gb of swap. Just try to imagine (calculate) what will happen if
you start swapping 1Gb.
This discussion usually comes hand in hand with the swap file vs. swap
partition discussion. I always felt that during the installation you
should install lots of swap space (~250Mb, or even more), just to be on
the safe side (with today's disks it doesn't make sense to save here). If
you go out of swap, add a swap file (don't re-partirion). Once you start
swapping, it is going to crawl anyway and it doesn't really matter which
of them you use. The obvious answer is to buy more memory.
> thus - allocate RAM based on your experience with the pattern of usage of
> your machine.
You ment allocate swap. Dito (and buy as much RAM to make sure that
programs don't swap).
> guy
>
> "For world domination - press 1,
> or dial 0, and please hold, for the creator." -- nob o. dy
>
>
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-- Yaron.
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