Sun Fire X4500, FreeBSD and ZFS

[Pawel Jakub Dawidek]

On Fri, May 04, 2007 at 06:26:14PM +0200, Kenneth Vestergaard Schmidt wrote:
> At the very least, we want to do some heavy testing with FreeBSD. If we
> get the time, it would be fun to contrast them to Solaris. It does
> require that I reinstall Solaris, though :)
> 
> How would you go about tweaking the machine for maximum efficiency? We
> have around 13 GB RAM free at the moment, just sitting doing nothing,
> and that might just as well be used for caching.

There is a lot memory and quite a few silly limits in the kernel.
Currently we allocate most memory for ZFS via malloc(9), so the memory
is allocate from kmem_map. This should change in the future, but until
then, you need to adjust vm_kmem_size, etc. to make memory usable with
ZFS. You'd also want to tune vfs.zfs.arc_max and vfs.zfs.arc_min,
because current auto-tuning won't be of any good from that much RAM. I'd
start from setting vfs.zfs.arc_max to kmem_map size minus 3GB. You can
tune all of them (vfs.zfs.arc_max, vfs.zfs.arc_min, vm.kmem_size and
vm.kmem_size_max from /boot/loader.conf).
Another old limit is for maximum number of vnodes in the system. It is
only auto-tuned up to 100000, which you may want to change. I'm not sure
if you can do it from kernel config, so just change MAXVNODES_MAX define
in sys/kern/vfs_subr.c.
Be aware that most debugging options like INVARIANTS, WITNESS, etc. have
very negative impact on ZFS performance in FreeBSD.

PS. Even if you don't want to install Solaris in there, there are plenty
benchmarks on the net for Solaris/ZFS on this very machine. Would be
good to know what results do we have.

Good luck!

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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