ZFS committed to the FreeBSD base.

Craig Boston craig at xfoil.gank.org
Tue Apr 10 01:30:37 UTC 2007

On Mon, Apr 09, 2007 at 09:11:25PM -0400, Kris Kennaway wrote:
> Nah, you were right the first time :) Your system is defaulting to
> 160MB for the kmem_map, of which zfs will (by default) try to use up
> to 3/4.  Naturally this doesn't leave much for the rest of the kernel
> (40MB), so you'll easily run the kernel out of memory.

Hmm, I had already reduced the maximum arc size to 64MB though, which I
figured (hoped?) would leave plenty of room.

So if kmem_size is the total size and it can't grow, what is
kmem_size_max?  Is there a way to see a sum of total kmem allocation?
Even the vm.zone breakdown seems to be gone in current so apparently my
knowledge of such things is becoming obsolete :)

> For now, you probably want to increase vm.kmem_size a bit to allow
> some more room for zfs, and set vfs.zfs.arc_max and arc_min to
> something more reasonable like 64*1024*1024+1 (the +1 is needed
> because zfs currently requires "greater than 64MB" for the arc).

Yeah, I found that out the hard way after wondering why it was ignoring
the tunables :)

I ran out of kmem_map space once with it set to 64*1024*1024+1, then I
modified the source so that it would accept zfs_arc_max >= (64 << 20)
instead, just in case it was a power-of-2 thing.


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