Re: 32-bit vs AMD64 on Opteron for LAMP server
Quoting Neil Gunton <neil@nilspace.com>:
Hi all,
I am going to be rebuilding a server in August which has been running
Sarge AMD64 for the last couple of years in a colo environment. I am
going to do a total rebuild (need to repartition the disks). Since I am
using the dpt_i2o drivers for Adaptec RAID, which I had a hell of a
problem getting to work under Sarge AMD64 (and still aren't in the
default modules for Etch), I am considering all options, including
simply using 32-bit Etch on the new install. This is a LAMP server,
running apache 1.3, mysql 5.
I am aware of some of the benefits of running 64-bit vs 32-bit on an
Opteron system, including larger memory addressing, more registers and
possibly better performance with larger numbers of connections.
However, I am wondering if anyone has actual experience of running a
real-world LAMP server, on the same hardware, using the same system,
using both 32-bit and 64-bit (not at the same time obviously!). In
other words, does anyone have real-world experience of whether AMD64
benefits are really apparent to this kind of application. I currently
have 4GB RAM on the server, and no intention to upgrade it soon. I
think the disk I/O will become an issue way before memory does (even
with kernel disk caching, it's just the impression I get from current
experience on my site with upward of 80-100,000 page requests per day
and fairly complex sql queries etc).
It would certainly make the install much more straightforward if I
could just use the i386 version of Etch, but if someone can tell me
that there really is substantial difference for LAMP type operation
with AMD64, then I'm all ears.
I don't have any facts or numbers to bring forward, but you probably
won't notice that much of a difference. Having said that, I would say
go for the AMD64 port. I don't think the install is anywhere near less
straightforward than the 32bit port.
But since you are running 4 Gig of RAM, take full advantage of it by
running amd64.
The developers have done a great job getting this port official and
you won't be disappointed with it. Its rock solid.
If you can, try both in a test environment, and then make your decision.
Perhaps there are some apache, or mysql benchmarks you can try?
Oh, and I would ask you if you have considered Software raid instead
of using an adaptec raid card? If you have time, try benchmarking
between them.
You might be suprised to see which one actually works better for you.
Cheers,
Mike
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