Re: i386 with PAE or AMD64 on PowerEdge with 4G RAM

2007/6/18, Jeremy Chadwick <koitsu@xxxxxxxxxxx>:

On Mon, Jun 18, 2007 at 01:03:44PM -0400, Martin Turgeon wrote:
> I just receive 2 PowerEdge servers (a 1950 and a 860) both with 4G of
RAM. I
> installed FreeBSD 6.2 Release i386 on both of them. Unfortunately, only
3,5G
> is recognized on the 860 and 3,3G on the 1950.
> dmesg on 860:
> real memory = 3757834240 (3583 MB)
> avail memory = 3678318592 (3507 MB)
>
> I am facing a difficult decision. Should I use i386 with PAE enabled in
the
> kernel (I read a lot of warnings using it) or should I go with AMD64?
Which
> branch should I follow?

Based on what I've read from some of the porters and miscellaneous
others, generally-speaking there's too many issues with amd64 (in the
sense of 32-bit vs. 64-bit compatibility -- not the fault of the kernel
or otherwise) to consider it worth switching to.

I personally don't run 64-bit OSes because most developers still use
32-bit machines and don't have a way to develop/test in 64-bit
environments.

That said, I'd recommend you stick with i386 + PAE, simply for
guaranteed application compatibility.


My setup is fairly standard (as I described), should I expect problem with
64 bit version of these programs?


You'll lose the amount of RAM you're seeing due to PAE addressing for
PCI address space. I can dig you up a usage map (broken down by how
much is taken up by each portion; PCI, ACPI, etc.) if you want one.
It's for SuperMicro systems, but the general idea applies to most
everything.


I'm not sure to understand what you mean by that. Are you saying that PAE
will eat the 500M that should be available?

--
| Jeremy Chadwick jdc at parodius.com |
| Parodius Networking http://www.parodius.com/ |
| UNIX Systems Administrator Mountain View, CA, USA |
| Making life hard for others since 1977. PGP: 4BD6C0CB |


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