ZFS and FreeBSD 7.2 ?

Dark Atheist

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amd64

FreeBSD 7.2+ has improved kernel memory allocation strategy and no tuning may be necessary on systems with more than 2 GB of RAM.
On systems using FreeBSD 7.0 and 7.1, kernel memory usage (vm.kmem_size) should be increased to around 1 GB and ARC size reduced:

  • vm.kmem_size_max="1024M"
  • vm.kmem_size="1024M"
  • vfs.zfs.arc_max="100M"
This might help if the machine is also loaded with other tasks, such as network activity (a file server), etc. Tuning KVA_PAGES is not required on amd64.
To increase performance, you may increase kern.maxvnodes (/etc/sysctl.conf) 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. AMD64 uses direct mapping for vnodes, so you don't have to worry about address space for vnodes on this architecture (as opposed to i386).
So is it still an idea to use that above even on 7.2 and its new kernel memory management?
 
not unless you see problems with stability or network/disk throughput to ZFS volumes.
 

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