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Date:      Wed, 02 Feb 2022 23:29:46 +0000
From:      bugzilla-noreply@freebsd.org
To:        doc@FreeBSD.org
Subject:   [Bug 261212] Update the ZFS chapter (20) of the FreeBSD Handbook, and other OpenZFS-related pages
Message-ID:  <bug-261212-9-k0fKnjnZe9@https.bugs.freebsd.org/bugzilla/>
In-Reply-To: <bug-261212-9@https.bugs.freebsd.org/bugzilla/>
References:  <bug-261212-9@https.bugs.freebsd.org/bugzilla/>

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D261212

Graham Perrin <grahamperrin@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Update the ZFS chapter (20) |Update the ZFS chapter (20)
                   |of the FreeBSD Handbook     |of the FreeBSD Handbook,
                   |                            |and other OpenZFS-related
                   |                            |pages

--- Comment #1 from Graham Perrin <grahamperrin@gmail.com> ---
Not the FreeBSD Handbook alone =E2=80=A6=20


Manual pages
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

<https://www.freebsd.org/cgi/man.cgi?query=3Dzfs&sektion=3D4&manpath=3DFree=
BSD>=20

* finds nothing for zfs(4) in FreeBSD 13.0.=20

Compare with OpenZFS <https://openzfs.github.io/openzfs-docs/man/4/zfs.4.ht=
ml>:=20

> zfs =E2=80=94 tuning of the ZFS kernel module

For zfs(4) in ports
<https://www.freebsd.org/cgi/man.cgi?query=3Dzfs&sektion=3D4&manpath=3DFree=
BSD-Ports>
=E2=80=93 more specifically,
<https://www.freebsd.org/cgi/man.cgi?query=3Dzfs&sektion=3D4&manpath=3DFree=
BSD+Ports+13.0>
in 'FreeBSD Ports 13.0' =E2=80=93 we have, for example:=20

> zfs_arc_max=3D0B (ulong)

There's a corresponding entry in the OpenZFS page for zfs(4).=20


Actual tunables
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

FreeBSD 13.0-RELEASE includes this variable:=20

    vfs.zfs.arc.max

=E2=80=93 the value of which defaults to:=20

    0

The name of the variable in FreeBSD is comparable to the name of the
parameter/variable in original OpenZFS documentation. Fair enough.=20


FreeBSD Handbook
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

<https://docs.freebsd.org/en/books/handbook/book/#zfs-advanced-tuning-arc_m=
ax>
describes this variable, with a different name, which probably predates Ope=
nZFS
in FreeBSD:=20

    vfs.zfs.arc_max

No mention of    0    and there's this:=20

> =E2=80=A6  all RAM but 1 GB, or 5/8 of all RAM, whichever is more.=20
> Use a lower value if =E2=80=A6

The word "but" is not ideal ("minus" would be better); and the reader might
wonder:=20

   Lower than what?

--=20
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