=head1 NAME

nbdkit-rotational-filter - set if a plugin is rotational or not

=head1 SYNOPSIS

 nbdkit --filter=rotational PLUGIN [rotational=true|false]

=head1 DESCRIPTION

C<nbdkit-rotational-filter> is a filter for L<nbdkit(1)> which lets
you change the rotational property of a plugin.

The rotational property is a boolean flag which hints to the client
whether the plugin behaves like a spinning disk (if rotational is
true) or like a solid state disk or RAM (if rotational is false).  If
a disk is rotational, then the client may attempt to schedule disk
accesses to reduce seek times using the elevator algorithm
(L<https://en.wikipedia.org/wiki/Elevator_algorithm>).

Adding this filter without using the C<rotational> parameter forces
the plugin to advertise that it is rotational.  You can explicitly set
the rotational property by using C<rotational=true> or
C<rotational=false>.

=head1 PARAMETERS

=over 4

=item B<rotational=true>

Set the rotational property, indicating that the plugin behaves like a
spinning disk.  This is the default when you enable this filter.

=item B<rotational=false>

Clear the rotational property, indicating that the plugin behaves like
a solid state disk or RAM.

=back

=head1 FILES

=over 4

=item F<$filterdir/nbdkit-rotational-filter.so>

The filter.

Use C<nbdkit --dump-config> to find the location of C<$filterdir>.

=back

=head1 VERSION

C<nbdkit-rotational-filter> first appeared in nbdkit 1.40.

=head1 SEE ALSO

L<nbdkit(1)>,
L<nbdkit-file-plugin(1)>,
L<nbdkit-readonly-filter(1)>,
L<nbdkit-spinning-filter(1)>,
L<nbdinfo(1)>,
L<nbdkit-filter(3)>,
L<https://en.wikipedia.org/wiki/Elevator_algorithm>.

=head1 AUTHORS

Richard W.M. Jones

=head1 COPYRIGHT

Copyright Red Hat
