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

Lars R. Noldan lars at w9zeb.org
Thu Feb 3 07:10:25 PST 2011

Hi Kris,

Further discussion in #PCBSD led me to realize my original thought was 
wrong.  That value is generated by the installer based on the available 
memory in the system rather than being a set value.

I think this one can be ignored.


On 02/03/2011 10:02 AM, Kris Moore wrote:
> Hash: SHA1
> On 02/02/2011 16:25, Lars R. Noldan wrote:
>> 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
> I guess the question would be what is the downside if we drop that max
> size? They have it set to that by default already, so there must have
> been a reason to pick it originally.
> - -- 
> Kris Moore
> PC-BSD Software
> iXsystems
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