Re: 32-bit vs AMD64 on Opteron for LAMP server
On Thursday 05 July 2007 22:07, Neil Gunton wrote:
> 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.
You won't be able to use all of your 4GB RAM with a 32-bit kernel. A 32-bit
processor only has 4GB of addressing space, and that has to be shared between
memory and peripherals.
You'd also do better with Apache 2.0 or 2.2, as long as you use the "prefork"
version (which is more compatible with PHP, if that's your chosen "P"). The
breaking-up of the configuration files is a bit of a pain to deal with, but
worth it in the long run (I knocked up a Perl script to break up a 1.3-style
configuration file into 2.0-style snippets; e-mail me if you are interested,
on-list if you think others would be interested). Otherwise it's just like
1.3, only faster.
If your RAID card is one of the ones that uses a binary-only driver, ignore it
and use the open source drivers with md RAID instead -- md is faster than any
manufacturer's proprietary alternative (anything that needs a driver is fake
RAID. True hardware RAID never needs a special driver; the array just shows
up as a single drive). Beside the non-polluted kernel, you also get the
advantage that you can have your swap area without redundancy, hence running
as fast as possible (just set up the partitions as separate swap areas).
--
AJS
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