svn commit: r44770 - head/en_US.ISO8859-1/books/handbook/config
Gavin Atkinson
gavin at FreeBSD.org
Sat May 17 19:52:19 UTC 2014
On Tue, 6 May 2014, Dru Lavigne wrote:
> Author: dru
> Date: Tue May 6 14:18:28 2014
> New Revision: 44770
> URL: http://svnweb.freebsd.org/changeset/doc/44770
>
> Log:
> Editorial review of Swap Space section.
> This really belongs in the Storage chapter and should have a reference for ZFS swap.
We generally recommend against using swap on ZFS, as it can currently be
unstable under low-memory or high-activity situations. This will likely
be fixed in the future though.
Generally, I'll create a separate gmirror partition or similar for swap,
and use the rest of the disks for the ZFS partiton.
Gavin
>
> Sponsored by: iXsystems
>
> Modified:
> head/en_US.ISO8859-1/books/handbook/config/chapter.xml
>
> Modified: head/en_US.ISO8859-1/books/handbook/config/chapter.xml
> ==============================================================================
> --- head/en_US.ISO8859-1/books/handbook/config/chapter.xml Tue May 6 13:38:06 2014 (r44769)
> +++ head/en_US.ISO8859-1/books/handbook/config/chapter.xml Tue May 6 14:18:28 2014 (r44770)
> @@ -2703,9 +2703,9 @@ kern.maxvnodes: 100000</screen>
> <sect1 xml:id="adding-swap-space">
> <title>Adding Swap Space</title>
>
> - <para>Sometimes a system requires more swap space. There are
> - three ways to increase swap space: add a new hard drive,
> - enable swap over <literal>NFS</literal>, or create a swap file
> + <para>Sometimes a system requires more swap space. This section
> + describes two methods to increase swap space: adding swap to an
> + existing partition or new hard drive, and creating a swap file
> on an existing partition.</para>
>
> <para>For information on how to encrypt swap space, which options
> @@ -2713,16 +2713,16 @@ kern.maxvnodes: 100000</screen>
> <xref linkend="swap-encrypting"/>.</para>
>
> <sect2 xml:id="new-drive-swap">
> - <title>Swap on a New or Existing Hard Drive</title>
> + <title>Swap on a New Hard Drive or Existing Partition</title>
>
> <para>Adding a new hard drive for swap gives better performance
> - than adding a partition on an existing drive. Setting up
> + than using a partition on an existing drive. Setting up
> partitions and hard drives is explained in
> <xref linkend="disks-adding"/> while
> <xref linkend="configtuning-initial"/> discusses partition
> layouts and swap partition size considerations.</para>
>
> - <para>Use &man.swapon.8; to add a swap partition to the system.
> + <para>Use <command>swapon</command> to add a swap partition to the system.
> For example:</para>
>
> <screen>&prompt.root; <userinput>swapon <replaceable>/dev/ada1s1b</replaceable></userinput></screen>
> @@ -2730,10 +2730,10 @@ kern.maxvnodes: 100000</screen>
> <warning>
> <para>It is possible to use any partition not currently
> mounted, even if it already contains data. Using
> - &man.swapon.8; on a partition that contains data will
> + <command>swapon</command> on a partition that contains data will
> overwrite and destroy that data. Make sure that the
> partition to be added as swap is really the intended
> - partition before running &man.swapon.8;.</para>
> + partition before running <command>swapon</command>.</para>
> </warning>
>
> <para>To automatically add this swap partition on boot, add an
> @@ -2742,34 +2742,26 @@ kern.maxvnodes: 100000</screen>
> <programlisting><replaceable>/dev/ada1s1b</replaceable> none swap sw 0 0</programlisting>
>
> <para>See &man.fstab.5; for an explanation of the entries in
> - <filename>/etc/fstab</filename>.</para>
> - </sect2>
> -
> - <sect2 xml:id="nfs-swap">
> - <title>Swapping over <literal>NFS</literal></title>
> -
> - <para>Swapping over <literal>NFS</literal> is only recommended
> - when there is no local hard disk to swap to.
> - <literal>NFS</literal> swapping will be limited by the
> - available network bandwidth and puts an additional burden
> - on &man.nfsd.8;.</para>
> + <filename>/etc/fstab</filename>. More information about
> + <command>swapon</command> can be found in
> + &man.swapon.8;.</para>
> </sect2>
>
> <sect2 xml:id="create-swapfile">
> - <title>Swapfiles</title>
> + <title>Creating a Swap File</title>
>
> - <para>To create a swap file, specify its size. The following
> + <para>To instead create a swap file, specify its size. The following
> example creates a 64MB file named
> <filename>/usr/swap0</filename>.</para>
>
> <example>
> - <title>Creating a Swapfile on &os;</title>
> + <title>Creating a Swap File on &os;</title>
>
> <orderedlist>
> <listitem>
> <para>The <filename>GENERIC</filename> kernel already
> - includes the memory disk driver (&man.md.4;) required
> - for this operation. When building a custom kernel,
> + includes the required memory disk driver.
> + When building a custom kernel,
> make sure to include the following line in the custom
> configuration file:</para>
>
> @@ -2780,31 +2772,33 @@ kern.maxvnodes: 100000</screen>
> </listitem>
>
> <listitem>
> - <para>First, create the swapfile
> + <para>Create the swap file,
> <filename>/usr/swap0</filename>:</para>
>
> - <screen>&prompt.root; <userinput>dd if=/dev/zero of=/usr/swap0 bs=1024k count=64</userinput></screen>
> + <screen>&prompt.root; <userinput>dd if=/dev/zero of=<replaceable>/usr/swap0</replaceable> bs=1024k count=<replaceable>64</replaceable></userinput></screen>
> </listitem>
>
> <listitem>
> <para>Then, set proper permissions on
> <filename>/usr/swap0</filename>:</para>
>
> - <screen>&prompt.root; <userinput>chmod 0600 /usr/swap0</userinput></screen>
> + <screen>&prompt.root; <userinput>chmod 0600 <replaceable>/usr/swap0</replaceable></userinput></screen>
> </listitem>
>
> <listitem>
> <para>Enable the swap file in
> <filename>/etc/rc.conf</filename>:</para>
>
> - <programlisting>swapfile="/usr/swap0" # Set to name of swapfile if aux swapfile desired.</programlisting>
> + <programlisting>swapfile="<replaceable>/usr/swap0</replaceable>" # Set to name of swap file</programlisting>
> </listitem>
>
> <listitem>
> - <para>Reboot the machine or, to enable the swap file
> - immediately, type:</para>
> + <para>To enable the swap file
> + immediately, specify a free memory device. Refer to
> + <xref linkend="disks-virtual"/> for more information
> + about memory devices.</para>
>
> - <screen>&prompt.root; <userinput>mdconfig -a -t vnode -f /usr/swap0 -u 0 && swapon /dev/md0</userinput></screen>
> + <screen>&prompt.root; <userinput>mdconfig -a -t vnode -f <replaceable>/usr/swap0</replaceable> -u <replaceable>0</replaceable> && swapon /dev/md<replaceable>0</replaceable></userinput></screen>
> </listitem>
> </orderedlist>
> </example>
>
>
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