[PC-BSD Testing] vfs.zfs.arch_max on 9.0 AMD64 (jan.13, 2011 snapshot)

[Lars R. Noldan]

This afternoon I spent some time playing with the installer, and trying 
to set up my system with a ZFS /

In doing this one thing I came across was it seems to fail stamping boot 
on ADA0 if I don't set any swap partition.  In talking with a few people 
it came to my attention that ZFS will happily consume all the ram in 
your system if you don't put a limitation on it.

The default vfs.zfs.arch_max via the install DVD reports as.

PCBSD# sysctl vfs.zfs.arch_max
vfs.zfs.arch_max: 9257951232

This shouldn't cause my system to fail as it has 12 gigs of ram in it.  
However that seems like a rather high default for the installation 
media.  Wouldn't ~4gb be a much more sane setting, as I suspect most 
AMD64 users are not going to be on a machine with > 4gb of ram?

Thanks
Lars