Max memory + swap

[Per Engelbrecht]

Hi Alessandro
(please use 72 char. per line)

> Tuesday, September 28, 2004, 10:13:34 AM, ha scritto:
>
>>> I was thinking of installing 1 Gb of RAM plus another Gigabytes
>>> of swap.
>
> PE> 'pstat -s' will tell you if you need more phy. ram.
>
> Of course, but since I'm planning to buy this new server just now
> I'ld add more RAM on its list, instead of buying it after few
> weeks.
>
>>> (without PAE or similar things, it's a "normal" P4 machine)
>
> PE> You have to use kernel PAE option if your fbsd4.x box should be
> able to PE> use anything above 4gb of ram. The installation can se
> the total amount PE> of ram, but can't use it - unless you compile
> the kernel with PAE option.
>
> so you too confirm swap space is NOT included in this math ?
> 2 Gb RAM + 4 Gb swap would work without enabling PAE ?

Phy. ram and swap space are two different things. The PAE option deals
with phy. ram allocation/management in the kernel. Swap has nothing to
do with this. It's merly a "helping hand" for systems running out of ram
... which you can "test" the use of/need for with 'pstat' (and 'wmstat')
as I mentioned in my previous mail.

>
> I'm afraid of PAE because of some "glitches" I read about with some
> HD controller drivers. Without PAE I feel more "safe" :)
> This will be a _very_ critical production server and I'm just
> taking all precautions I can in order to gain maximum availabily
> and
> stability.

There's no "glitches" with PAE. If HA is such a big issue, the amount of
ram should not be an issue in the first place - buy big.
Don't get offended, but if it's because you don't like to recompile a
kernel (just guessing) read the documentation on the fbsd site - it's a
dicipline you'll have to master (it's easy and it's mandatory).

>
> PE> Don't know about limits in fbsd5.x but I'm sure it's "fixed".
>
> Unfortunately for my purposes 5.x is not yet an option, also if I'm
> waiting 5.3-rel. for start an our own internal test program :)

The 5.x branch is differnt from the 4.x branche in a number of ways and
5.2[1] is a good place to start. Fbsd 5.3 is close to a release now, but
if you have a sandbox don't wait. Start testing/playing now!

>
>
>>> Anyone with similar experiences could, please, remember me actual
>>> limits ?
>
> PE> I run production serveres fbsd4.10 with 4gb of ram and with PAE
> compiled PE> into the kernel.
>
> How much swap space do you have configured, if any ?
> May I ask you, if possible, which HD controller drivers are you
> using ? (reply in private mail if you think it's better ;) )

fbsd4.10, Xeon, 4gb ram, 1024m swap (swap use 0), AIC-7990 (U320 / ahd)
This is a public maillist thread, why should I feel better by posting my
answer directly to you ?

/per
per at xterm.dk


>
> PE> P.S. don't cross-post a thread to several liste like you've
> done with PE> this one. Stick to one and only one list. People are
> kind enough to PE> point you to another list if you're on the wrong
> one.
>
> Yep, sorry but I was not sure which list was the correct one for my
> question ;) :(
>
>
> Many thanks !!
>
>
> --
>
> Alessandro de Manzano
>
> System & Network Administrator
> Playstos - TIMA S.p.A.
> Corso Sempione 63
> 20149 Milano, Italy
>
> tel.: +39-023314153
> fax : +39-02315678
> email: demanzano at playstos.com
>
> http://www.playstos.com