Date: Thu, 29 Aug 2013 14:56:44 -0700 From: Freddie Cash <fjwcash@gmail.com> To: Berend de Boer <berend@pobox.com> Cc: FreeBSD FS <freebsd-fs@freebsd.org> Subject: Re: NFS on ZFS pure SSD pool Message-ID: <CAOjFWZ6KQHj939dFiemHSEyhK7eeXuYPLqs5zWYN2tXa3685Hg@mail.gmail.com> In-Reply-To: <877gf4cj7o.wl%berend@pobox.com> References: <CAOFF%2BZ3jNvnWbE5C8LarRE7-SQbB4Q9NJTn01J=FGP9uppKdaw@mail.gmail.com> <1079189088.15197172.1377784177805.JavaMail.root@uoguelph.ca> <CAOFF%2BZ0SRDUNuaT73e4jU%2BFZESR35OS8Vo9cU-bV2-zn-HhWDw@mail.gmail.com> <CAOjFWZ6sigqx8LxMHmDvvH7XoNi-GCW=q1YzoXUoDq%2BOOBsC9Q@mail.gmail.com> <877gf4cj7o.wl%berend@pobox.com>
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On Thu, Aug 29, 2013 at 1:53 PM, Berend de Boer <berend@pobox.com> wrote: > >>>>> "Freddie" == Freddie Cash <fjwcash@gmail.com> writes: > > Freddie> This will show you how many bytes of the ARC are being > Freddie> used by metadata: sysctl vfs.zfs.arc_meta_used > > Freddie> You can tune what the max is via: sysctl > Freddie> vfs.zfs.arc_meta_limit > > Strangely enough on my system arc_meta_used = 2GB, while > arc_meta_limit = 1.5G. > > Wouldn't you expect that arc_meta_used would be lower than this limit? > You would think so. Maybe this is not a hard limit, but a high-water mark that leads to an eviction process running? Don't know, I'm not at all versed in the inner workings of ZFS. :) I do know other vfs.zfs.*limit tunables were high-water marks and work was underway to turn them into hard limits. Maybe this needs to be added to that list? Maybe it's not worth worrying about? -- Freddie Cash fjwcash@gmail.com
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