ZFS and PAE
olli at lurza.secnetix.de
Mon Feb 11 10:55:16 UTC 2008
Aristedes Maniatis wrote:
> Given the high memory usage requirements of ZFS, I'd like to load up
> servers using it with as much memory as I can. More than 4Gb of memory
> on older 32bit CPUs. Since PAE doesn't play with loadable kernel
> modules, is there a way to compile ZFS into the kernel itself (if I
> tick a box that says I know that licensing issues exist)?
When you hit the 4 GB limit in FreeBSD/i386, the main issue
with ZFS is address space, not RAM.
Running at 32bit, you will always have the 4 GB limit for
KVM + userspace address space, no matter how much RAM you
actually have, and no matter whether you use PAE or not.
The additional RAM beyond 4 GB will not help much for ZFS,
even with PAE.
If your processor supports 64bit mode, then take advantage
of that if you want to use ZFS. If your processor is 32bit
only, buying huge amounts of RAM and enabling PAE will not
compensate for the lack of 64bit support. Better spend the
money on 64bit capable hardware.
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