ZFS Tuning Guide
(Work in Progress)
To use ZFS 1GB of memory is recommended but, more is helpful as ZFS does lots of caching. A amd64 system is preferred due to the larger address space.
amd64
On amd64 it helps to crank kern.maxvnodes way up if you have the RAM for it (e.g. 400000 for a 2GB system). Keep an eye on vfs.numvnodes during production to see where it stabilizes.
i386
Minimum recommended memory: 1 GB
Even on machines with enough memory, several configuration knobs need to be altered to ensure stable operation. Here's an example configuration for a machine with 1 GB memory:
- kern.maxvnodes="50000" (sysctl)
- vfs.zfs.prefetch_disable="1" (loader.conf)
- vfs.zfs.arc_max="83886080" (loader.conf)
- vm.kmem_size_max="268435456" (loader.conf)
On machines with less than 1 GB memory, some options to try are:
- vfs.zfs.zil_disable="1" (loader.conf)
- For 512 MB, reduce kern.maxvnodes and vfs.zfs.arc_max to half their value, for 256 MB, to quarter, etc.