Integrate new chapters of the Handbook into the Greek build.

This is still work in progress (as not everything is translated yet) but it makes life easier for us if the 'official' and our test builds are in sync.

New files:

el_GR.ISO8859-7/books/handbook/dtrace Makefile & chapter.sgml (Synopsis translated)
el_GR.ISO8859-7/books/handbook/updating Makefile & chapter.sgml (Completely translated)
el_GR.ISO8859-7/books/handbook/filesystems Makefile & chapter.sgml (Synopsis translated)

Modified files:

MFen: 1.109 -> 1.110	en_US.ISO8859-1/books/handbook/Makefile
MFen: 1.172 -> 1.173	en_US.ISO8859-1/books/handbook/book.sgml
MFen: 1.37  -> 1.38	en_US.ISO8859-1/books/handbook/chapters.ent

Obtained from: FreeBSD Greek Documentation Project

1 files changed, 630 insertions, 0 deletions

diff --git a/el_GR.ISO8859-7/books/handbook/filesystems/chapter.sgml b/el_GR.ISO8859-7/books/handbook/filesystems/chapter.sgml
new file mode 100644
index 0000000000..18d6e92a6d
--- /dev/null
+++ b/el_GR.ISO8859-7/books/handbook/filesystems/chapter.sgml
@@ -0,0 +1,630 @@
+<!--
+
+  Το Εγχειρίδιο του FreeBSD: Συστήματα Αρχείων
+
+  The FreeBSD Greek Documentation Project
+
+  $FreeBSD$
+
+  %SOURCE%	en_US.ISO8859-1/books/handbook/filesystems/chapter.sgml
+  %SRCID%	1.3
+
+-->
+
+<chapter id="filesystems">
+  <chapterinfo>
+    <authorgroup>
+      <author>
+	<firstname>Tom</firstname>
+	<surname>Rhodes</surname>
+	<contrib>Γράφηκε από τον </contrib>
+      </author>
+    </authorgroup>
+  </chapterinfo>
+
+  <title>Υποστήριξη Συστημάτων Αρχείων</title>
+
+  <sect1 id="filesystems-synopsis">
+    <title>Σύνοψη</title>
+
+    <indexterm><primary>File Systems</primary></indexterm>
+    <indexterm>
+      <primary>File Systems Support</primary>
+      <see>File Systems</see>
+    </indexterm>
+
+    <para>Τα συστήματα αρχείων αποτελούν αναπόσπαστο τμήμα κάθε λειτουργικού
+      συστήματος.  Επιτρέπουν στους χρήστες να δημιουργούν και να αποθηκεύουν
+      αρχεία, παρέχουν πρόσβαση σε δεδομένα, και φυσικά αξιοποιούν τους
+      σκληρούς δίσκους.  Διαφορετικά λειτουργικά συστήματα χρησιμοποιούν
+      συνήθως διαφορετικά εγγενή συστήματα αρχείων.  Το σύστημα αρχείων του
+      &os; είναι το Fast File System ή <acronym>FFS</acronym>, το
+      οποίο προήλθε από το αρχικό σύστημα αρχείων του Unix&trade;, γνωστό
+      επίσης και ως <acronym>UFS</acronym>.  Αυτό είναι και το εγγενές
+      σύστημα αρχείων του &os;, το οποίο χρησιμοποιείται στους σκληρούς
+      δίσκους και προσφέρει πρόσβαση στα δεδομένα.</para>
+
+    <para>Το &os; προσφέρει επίσης πληθώρα διαφορετικών συστημάτων αρχείων,
+      ώστε να παρέχει τοπική πρόσβαση σε δεδομένα που έχουν δημιουργηθεί από
+      άλλα λειτουργικά συστήματα, π.χ.&nbsp;δεδομένα που βρίσκονται σε τοπικά
+      <acronym>USB</acronym> αποθηκευτικά μέσα, οδηγούς flash, και σκληρούς
+      δίσκους.  Υπάρχει επίσης υποστήριξη για άλλα, μη-εγγενή συστήματα
+      αρχείων, όπως το το Extended File System (<acronym>EXT</acronym>) του
+      &linux; καθώς και το σύστημα Z File System (<acronym>ZFS</acronym>) της
+      &sun;.</para>
+
+    <para>Το &os; παρέχει διαφορετικό επίπεδο υποστήριξης για κάθε σύστημα
+      αρχείων.  Για ορισμένα θα χρειαστεί να φορτωθεί κάποιο άρθρωμα στον
+      πυρήνα, ενώ για άλλα θα πρέπει να εγκατασταθούν κάποια εργαλεία.
+      Το κεφάλαιο αυτό έχει σχεδιαστεί να βοηθήσει τους χρήστες του &os; να
+      αποκτήσουν πρόσβαση σε άλλα συστήματα αρχείων στο σύστημα τους,
+      ξεκινώντας από το Ζ File System της &sun;.</para>
+
+    <para>Αφού διαβάσετε αυτό το κεφάλαιο, θα γνωρίζετε:</para>
+
+    <itemizedlist>
+      <listitem>
+	<para>Τη διαφορά μεταξύ των εγγενών και των υποστηριζόμενων
+	  συστημάτων αρχείων.</para>
+      </listitem>
+
+      <listitem>
+	<para>Ποια συστήματα αρχείων υποστηρίζονται από το &os;.</para>
+      </listitem>
+
+      <listitem>
+	<para>Πως να ενεργοποιήσετε, να ρυθμίσετε, να αποκτήσετε πρόσβαση και
+	  να χρησιμοποιήσετε μη-εγγενή συστήματα αρχείων.</para>
+      </listitem>
+    </itemizedlist>
+
+    <para>Πριν διαβάσετε αυτό το κεφάλαιο, θα πρέπει:</para>
+
+    <itemizedlist>
+      <listitem>
+	<para>Να κατανοείτε βασικές έννοιες του &unix; και του &os;
+	  (<xref linkend="basics">).</para>
+      </listitem>
+
+      <listitem>
+	<para>Να είστε εξοικειωμένος με τις βασικές διαδικασίες ρύθμισης και
+	  εγκατάστασης προσαρμοσμένου πυρήνα
+	  (<xref linkend="kernelconfig">).</para>
+      </listitem>
+
+      <listitem>
+	<para>Να αισθάνεστε άνετα με την εγκατάσταση εφαρμογών τρίτου
+	  κατασκευαστή στο &os; (<xref linkend="ports">).</para>
+      </listitem>
+
+      <listitem>
+	<para>Να είστε εξοικειωμένος με τους δίσκους, τα μέσα
+	  αποθήκευσης, και τα αντίστοιχα ονόματα συσκευών στο
+	  &os; (<xref linkend="disks">).</para>
+      </listitem>
+    </itemizedlist>
+
+    <!--
+      Temporary warning to avoid listing experimental versions
+      and production versions of FreeBSD with this technology.
+    -->
+    <warning>
+      <para>Τη δεδομένη στιγμή, το <acronym>ZFS</acronym> θεωρείται
+	δοκιμαστική δυνατότητα.  Μερικές επιλογές μπορεί να υπολείπονται
+	λειτουργικότητας, και άλλες μπορεί να μη λειτουργούν καθόλου.  Με
+	την πάροδο του χρόνου, η δυνατότητα αυτή θα θεωρηθεί έτοιμη για χρήση
+	σε περιβάλλοντα παραγωγής, και η παρούσα τεκμηρίωση θα ανανεωθεί ώστε
+	να αντιπροσωπεύει αυτή την κατάσταση.</para>
+    </warning>
+  </sect1>
+
+  <sect1 id="filesystems-zfs">
+    <title>The Z File System</title>
+
+    <para>The Z&nbsp;file system, developed by &sun;, is a new
+      technology designed to use a pooled storage method.  This means
+      that space is only used as it is needed for data storage.  It
+      has also been designed for maximum data integrity, supporting
+      data snapshots, multiple copies, and data checksums.  A new
+      data replication model, known as <acronym>RAID</acronym>-Z has
+      been added.  The <acronym>RAID</acronym>-Z model is similar
+      to <acronym>RAID</acronym>5 but is designed to prevent data
+      write corruption.</para>
+
+    <sect2>
+      <title>ZFS Tuning</title>
+
+      <para>The <acronym>ZFS</acronym> subsystem utilizes much of
+	the system resources, so some tuning may be required to provide
+	maximum efficiency during every-day use.  As an experimental
+	feature in &os; this may change in the near future; however,
+	at this	time, the following steps are recommended.</para>
+
+      <sect3>
+	<title>Memory</title>
+
+	<para>The total system memory should be at least one gigabyte,
+	  with two gigabytes or more recommended.  In all of the
+	  examples here, the system has one gigabyte of memory with
+	  several other tuning mechanisms in place.</para>
+
+	<para>Some people have had luck using fewer than one gigabyte
+	  of memory, but with such a limited amount of physical memory,
+	  when the system is under heavy load, it is very plausible
+	  that &os; will panic due to memory exhaustion.</para>
+      </sect3>
+
+      <sect3>
+	<title>Kernel Configuration</title>
+
+	<para>It is recommended that unused drivers and options
+	  be removed from the kernel configuration file.  Since most
+	  devices are available as modules, they may simply be loaded
+	  using the <filename>/boot/loader.conf</filename> file.</para>
+
+	<para>Users of the i386 architecture should add the following
+	  option to their kernel configuration file, rebuild their
+	  kernel, and reboot:</para>
+
+	<programlisting>options 	KVA_PAGES=512</programlisting>
+
+	<para>This option will expand the kernel address space, thus
+	  allowing the <varname>vm.kvm_size</varname> tunable to be
+	  pushed beyond the currently imposed limit of 1&nbsp;GB
+	  (2&nbsp;GB for <acronym>PAE</acronym>).  To find the most
+	  suitable value for this option, divide the desired address
+	  space in megabytes by four (4).  In this case, it is
+	  <literal>512</literal> for 2&nbsp;GB.</para>
+      </sect3>
+
+      <sect3>
+	<title>Loader Tunables</title>
+
+	<para>The <devicename>kmem</devicename> address space should be
+	  increased on all &os; architectures.  On the test system with
+	  one gigabyte of physical memory, success was achieved with the
+	  following options which should be placed in
+	  the <filename>/boot/loader.conf</filename> file and the system
+	  restarted:</para>
+
+	<programlisting>vm.kmem_slze="330M"
+vm.kmem_size_max="330M"
+vfs.zfs.arc_max="40M"
+vfs.zfs.vdev.cache.size="5M"</programlisting>
+
+	<para>For a more detailed list of recommendations for ZFS-related
+	  tuning, see
+	  <ulink url="http://wiki.freebsd.org/ZFSTuningGuide"></ulink>.</para>
+      </sect3>
+    </sect2>
+
+    <sect2>
+      <title>Using <acronym>ZFS</acronym></title>
+
+      <para>There is a start up mechanism that allows &os; to
+	mount <acronym>ZFS</acronym> pools during system
+	initialization.  To set it, issue the following
+	commands:</para>
+
+	<screen>&prompt.root; <userinput>echo 'zfs_enable="YES"' &gt;&gt; /etc/rc.conf</userinput>
+&prompt.root; <userinput>/etc/rc.d/zfs start</userinput></screen>
+
+	<para>The remainder of this document assumes two
+	  <acronym>SCSI</acronym> disks are available, and their device names
+	  are <devicename><replaceable>da0</replaceable></devicename>
+	  and <devicename><replaceable>da1</replaceable></devicename>
+	  respectively.  Users of <acronym>IDE</acronym> hardware may
+	  use the <devicename><replaceable>ad</replaceable></devicename>
+	  devices in place of <acronym>SCSI</acronym> hardware.</para>
+
+      <sect3>
+	<title>Single Disk Pool</title>
+
+	<para>To create a <acronym>ZFS</acronym> over a single disk
+	  device, use the <command>zpool</command> command:</para>
+
+	<screen>&prompt.root; <userinput>zpool create example /dev/da0</userinput></screen>
+
+	<para>To view the new pool, review the output of the
+	  <command>df</command>:</para>
+
+	<screen>&prompt.root; <userinput>df</userinput>
+Filesystem  1K-blocks    Used    Avail Capacity  Mounted on
+/dev/ad0s1a   2026030  235230  1628718    13%    /
+devfs               1       1        0   100%    /dev
+/dev/ad0s1d  54098308 1032846 48737598     2%    /usr
+example      17547136       0 17547136     0%    /example</screen>
+
+	<para>This output clearly shows the <literal>example</literal>
+	  pool has not only been created but
+	  <emphasis>mounted</emphasis> as well.  It is also accessible
+	  just like a normal file system, files may be created on it
+	  and users are able to browse it as in the
+	  following example:</para>
+
+	<screen>&prompt.root <userinput>cd /example</userinput>
+&prompt.root; <userinput>ls</userinput>
+&prompt.root; <userinput>touch testfile</userinput>
+&prompt.root; <userinput>ls -al</userinput>
+total 4
+drwxr-xr-x   2 root  wheel    3 Aug 29 23:15 .
+drwxr-xr-x  21 root  wheel  512 Aug 29 23:12 ..
+-rw-r--r--   1 root  wheel    0 Aug 29 23:15 testfile</screen>
+
+	<para>Unfortunately this pool is not taking advantage of
+	  any <acronym>ZFS</acronym> features.  Create a file system
+	  on this pool, and enable compression on it:</para>
+
+	<screen>&prompt.root; <userinput>zfs create example/compressed</userinput>
+&prompt.root; <userinput>zfs set compression=gzip example/compressed</userinput></screen>
+
+	<para>The <literal>example/compressed</literal> is now a
+	  <acronym>ZFS</acronym> compressed file system.  Try copying
+	  some large files to it by copying them to
+	  <filename class="directory">/example/compressed</filename>.</para>
+
+	<para>The compression may now be disabled with:</para>
+
+	<screen>&prompt.root; <userinput>zfs set compression=off example/compressed</userinput></screen>
+
+	<para>To unmount the file system, issue the following command
+	  and then verify by using the <command>df</command>
+	  utility:</para>
+
+	<screen>&prompt.root; <userinput>zfs umount example/compressed</userinput>
+&prompt.root; <userinput>df</userinput>
+Filesystem  1K-blocks    Used    Avail Capacity  Mounted on
+/dev/ad0s1a   2026030  235232  1628716    13%    /
+devfs               1       1        0   100%    /dev
+/dev/ad0s1d  54098308 1032864 48737580     2%    /usr
+example      17547008       0 17547008     0%    /example</screen>
+
+	<para>Re-mount the file system to make it accessible
+	  again, and verify with <command>df</command>:</para>
+
+	<screen>&prompt.root; <userinput>zfs mount example/compressed</userinput>
+&prompt.root; <userinput>df</userinput>
+Filesystem         1K-blocks    Used    Avail Capacity  Mounted on
+/dev/ad0s1a          2026030  235234  1628714    13%    /
+devfs                      1       1        0   100%    /dev
+/dev/ad0s1d         54098308 1032864 48737580     2%    /usr
+example             17547008       0 17547008     0%    /example
+example/compressed  17547008       0 17547008     0%    /example/compressed</screen>
+
+	<para>The pool and file system may also be observed by viewing
+	  the output from <command>mount</command>:</para>
+
+	<screen>&prompt.root; <userinput>mount</userinput>
+/dev/ad0s1a on / (ufs, local)
+devfs on /dev (devfs, local)
+/dev/ad0s1d on /usr (ufs, local, soft-updates)
+example on /example (zfs, local)
+example/data on /example/data (zfs, local)
+example/compressed on /example/compressed (zfs, local)</screen>
+
+	<para>As observed, <acronym>ZFS</acronym> file systems, after
+	  creation, may be used like ordinary file systems; however,
+	  many other features are also available.  In the following
+	  example, a new file system, <literal>data</literal> is
+	  created.  Important files will be stored here, so the file
+	  system is set to keep two copies of each data block:</para>
+
+	<screen>&prompt.root; <userinput>zfs create example/data</userinput>
+&prompt.root; <userinput>zfs set copies=2 example/data</userinput></screen>
+
+	<para>It is now possible to see the data and space utilization
+	  by issuing the <command>df</command> again:</para>
+
+	<screen>&prompt.root; <userinput>df</userinput>
+Filesystem         1K-blocks    Used    Avail Capacity  Mounted on
+/dev/ad0s1a          2026030  235234  1628714    13%    /
+devfs                      1       1        0   100%    /dev
+/dev/ad0s1d         54098308 1032864 48737580     2%    /usr
+example             17547008       0 17547008     0%    /example
+example/compressed  17547008       0 17547008     0%    /example/compressed
+example/data        17547008       0 17547008     0%    /example/data</screen>
+
+	<para>Notice that each file system on the pool has the same
+	  amount of available space.  This is the reason for using
+	  the <command>df</command> through these examples, to show
+	  that the file systems are using only the amount of space
+	  they need and will all draw from the same pool.
+	  The <acronym>ZFS</acronym> file system does away with concepts
+	  such as volumes and partitions, and allows for several file
+	  systems to occupy the same pool.  Destroy the file systems,
+	  and then destroy the pool as they are no longer
+	  needed:</para>
+
+	<screen>&prompt.root; <userinput>zfs destroy example/compressed</userinput>
+&prompt.root; <userinput>zfs destroy example/data</userinput>
+&prompt.root; <userinput>zpool destroy example</userinput></screen>
+
+	<para>Disks go bad and fail, an unavoidable trait.  When
+	  this disk goes bad, the data will be lost.  One method of
+	  avoiding data loss due to a failed hard disk is to implement
+	  a <acronym>RAID</acronym>.  <acronym>ZFS</acronym> supports
+	  this feature in its pool design which is covered in
+	  the next section.</para>
+      </sect3>
+
+      <sect3>
+	<title><acronym>ZFS</acronym> RAID-Z</title>
+
+	<para>As previously noted, this section will assume that
+	  two <acronym>SCSI</acronym> exists as devices
+	  <devicename>da0</devicename> and
+	  <devicename>da1</devicename>.  To create a
+	  <acronym>RAID</acronym>-Z pool, issue the following
+	  command:</para>
+
+	<screen>&prompt.root; <userinput>zpool create storage raidz da0 da1</userinput></screen>
+
+	<para>The <literal>storage</literal> zpool should have been
+	  created.  This may be verified by using the &man.mount.8; and
+	  &man.df.1; commands as before.  More disk devices may have
+	  been allocated by adding them to the end of the list above.
+	  Make a new file system in the pool, called
+	  <literal>home</literal> where user files will eventually be
+	  placed:</para>
+
+	<screen>&prompt.root; <userinput>zfs create storage/home</userinput></screen>
+
+	<para>It is now possible to enable compression and keep extra
+	  copies of the user's home directories and files.  This may
+	  be accomplished just as before using the following
+	  commands:</para>
+
+	<screen>&prompt.root; <userinput>zfs set copies=2 storage/home</userinput>
+&prompt.root; <userinput>zfs set compression=gzip storage/home</userinput></screen>
+
+	<para>To make this the new home directory for users, copy the
+	  user data to this directory, and create the appropriate
+	  symbolic links:</para>
+
+	<screen>&prompt.root; <userinput>cp -rp /home/* /storage/home</userinput>
+&prompt.root; <userinput>rm -rf /home /usr/home</userinput>
+&prompt.root; <userinput>ln -s /storage/home /home</userinput>
+&prompt.root; <userinput>ln -s /storage/home /usr/home</userinput></screen>
+
+	<para>Users should now have their data stored on the freshly
+	  created <filename class="directory">/storage/home</filename>
+	  file system.  Test by adding a new user and logging in as
+	  that user.</para>
+
+	<para>Try creating a snapshot which may be rolled back
+	  later:</para>
+
+	<screen>&prompt.root; <userinput>zfs snapshot storage/home@08-30-08</userinput></screen>
+
+	<para>Note that the snapshot option will only capture a real
+	  file system, not a home directory or a file.  The
+	  <literal>@</literal> character is a delimiter used between
+	  the file system name or the volume name.  When a user's
+	  home directory gets trashed, restore it with:</para>
+
+	<screen>&prompt.root; <userinput>zfs rollback storage/home@08-30-08</userinput></screen>
+
+	<para>To get a list of all available snapshots, run the
+	  <command>ls</command> in the file system's
+	  <filename class="directory">.zfs/snapshot</filename>
+	  directory.  For example, to see the previously taken
+	  snapshot, perform the following command:</para>
+
+	<screen>&prompt.root; <userinput>ls /storage/home/.zfs/snapshot</userinput></screen>
+
+	<para>It is possible to write a script to perform monthly
+	  snapshots on user data; however, over time, snapshots
+	  may consume a great deal of disk space.  The previous
+	  snapshot may be removed using the following command:</para>
+
+	<screen>&prompt.root; <userinput>zfs destroy storage/home@08-30-08</userinput></screen>
+
+	<para>There is no reason, after all of this testing, we should
+	  keep <filename class="directory">/storage/home</filename>
+	  around in its present state.  Make it the real
+	  <filename class="directory">/home</filename> file
+	  system:</para>
+
+	<screen>&prompt.root; <userinput>zfs set mountpoint=/home storage/home</userinput></screen>
+
+	<para>Issuing the <command>df</command> and
+	  <command>mount</command> commands will show that the system
+	  now treats our file system as the real
+	  <filename class="directory">/home</filename>:</para>
+
+	<screen>&prompt.root; <userinput>mount</userinput>
+/dev/ad0s1a on / (ufs, local)
+devfs on /dev (devfs, local)
+/dev/ad0s1d on /usr (ufs, local, soft-updates)
+storage on /storage (zfs, local)
+storage/home on /home (zfs, local)
+&prompt.root; <userinput>df</userinput>
+Filesystem   1K-blocks    Used    Avail Capacity  Mounted on
+/dev/ad0s1a    2026030  235240  1628708    13%    /
+devfs                1       1        0   100%    /dev
+/dev/ad0s1d   54098308 1032826 48737618     2%    /usr
+storage       17547008       0 17547008     0%    /storage
+storage/home  17547008       0 17547008     0%    /home</screen>
+
+	<para>This completes the <acronym>RAID</acronym>-Z
+	  configuration.  To get status updates about the file systems
+	  created during the nightly &man.periodic.8; runs, issue the
+	  following command:</para>
+
+	<screen>&prompt.root; <userinput>echo 'daily_status_zfs_enable="YES"' &gt;&gt; /etc/periodic.conf</userinput></screen>
+      </sect3>
+
+      <sect3>
+	<title>Recovering <acronym>RAID</acronym>-Z</title>
+
+	<para>Every software <acronym>RAID</acronym> has a method of
+	  monitoring their <literal>state</literal>.
+	  <acronym>ZFS</acronym> is no exception.  The status of
+	  <acronym>RAID</acronym>-Z devices may be viewed with the
+	  following command:</para>
+
+	<screen>&prompt.root; <userinput>zpool status -x</userinput></screen>
+
+	<para>If all pools are healthy and everything is normal, the
+	  following message will be returned:</para>
+
+	<screen>all pools are healthy</screen>
+
+	<para>If there is an issue, perhaps a disk has gone offline,
+	  the pool state will be returned and look similar to:</para>
+
+	<screen>  pool: storage
+ state: DEGRADED
+status: One or more devices has been taken offline by the administrator.
+	Sufficient replicas exist for the pool to continue functioning in a
+	degraded state.
+action: Online the device using 'zpool online' or replace the device with
+	'zpool replace'.
+ scrub: none requested
+config:
+
+	NAME        STATE     READ WRITE CKSUM
+	storage     DEGRADED     0     0     0
+	  raidz1    DEGRADED     0     0     0
+	    da0     ONLINE       0     0     0
+	    da1     OFFLINE      0     0     0
+
+errors: No known data errors</screen>
+
+	<para>This states that the device was taken offline by the
+	  administrator.  This is true for this particular example.
+	  To take the disk offline, the following command was
+	  used:</para>
+
+	<screen>&prompt.root; <userinput>zpool offline storage da1</userinput></screen>
+
+	<para>It is now possible to replace the
+	  <devicename>da1</devicename> after the system has been
+	  powered down.  When the system is back online, the following
+	  command may issued to replace the disk:</para>
+
+	<screen>&prompt.root; <userinput>zpool replace storage da1</userinput></screen>
+
+	<para>From here, the status may be checked again, this time
+	  without the <option>-x</option> flag to get state
+	  information:</para>
+
+	<screen>&prompt.root; <userinput>zpool status storage</userinput>
+ pool: storage
+ state: ONLINE
+ scrub: resilver completed with 0 errors on Sat Aug 30 19:44:11 2008
+config:
+
+	NAME        STATE     READ WRITE CKSUM
+	storage     ONLINE       0     0     0
+	  raidz1    ONLINE       0     0     0
+	    da0     ONLINE       0     0     0
+	    da1     ONLINE       0     0     0
+
+errors: No known data errors</screen>
+
+	<para>As shown from this example, everything appears to be
+	  normal.</para>
+      </sect3>
+
+      <sect3>
+	<title>Data Verification</title>
+
+	<para>As previously mentioned, <acronym>ZFS</acronym> uses
+	  <literal>checksums</literal> to verify the integrity of
+	  stored data.  They are enabled automatically upon creation
+	  of file systems and may be disabled using the following
+	  command:</para>
+
+	<screen>&prompt.root; <userinput>zfs set checksum=off storage/home</userinput></screen>
+
+	<para>This is not a wise idea; however, as checksums take
+	  very little storage space and are more useful enabled.  There
+	  also appear to be no noticeable costs having them enabled.
+	  While enabled, it is possible to have <acronym>ZFS</acronym>
+	  check data integrity using checksum verification.  This
+	  process is known as <quote>scrubing.</quote>  To verify the
+	  data integrity of the <literal>storage</literal> pool, issue
+	  the following command:</para>
+
+	<screen>&prompt.root; <userinput>zpool scrub storage</userinput></screen>
+
+	<para>This process may take considerable time depending on
+	  the amount of data stored.  It is also very
+	  <acronym>I/O</acronym> intensive, so much that only one
+	  of these operations may be run at any given time.  After
+	  the scrub has completed, the status is updated and may be
+	  viewed by issuing a status request:</para>
+
+	<screen>&prompt.root; <userinput>zpool status storage</userinput>
+ pool: storage
+ state: ONLINE
+ scrub: scrub completed with 0 errors on Sat Aug 30 19:57:37 2008
+config:
+
+	NAME        STATE     READ WRITE CKSUM
+	storage     ONLINE       0     0     0
+	  raidz1    ONLINE       0     0     0
+	    da0     ONLINE       0     0     0
+	    da1     ONLINE       0     0     0
+
+errors: No known data errors</screen>
+
+	<para>The completion time is in plain view in this example.
+	  This feature helps to ensure data integrity over a long
+	  period of time.</para>
+
+	<para>There are many more options for the Z&nbsp;file system,
+	  see the &man.zfs.8; and &man.zpool.8; manual
+	  pages.</para>
+      </sect3>
+    </sect2>
+  </sect1>
+
+
+  <!--
+      XXXTR: stub sections (added later, as needed, as desire,
+      after I get opinions from -doc people):
+
+      Still need to discuss native and foreign file systems.
+
+  <sect1>
+    <title>Device File System</title>
+  </sect1>
+
+  <sect1>
+    <title>DOS and NTFS File Systems</title>
+    <para>This is a good section for those who transfer files, using
+      USB devices, from Windows to FreeBSD and vice-versa.  My camera,
+      and many other cameras I have seen default to using FAT16.  There
+      is (was?) a kde utility, I think called kamera, that could be used
+      to access camera devices.  A section on this would be useful.</para>
+
+    <para>XXXTR: Though!  The disks chapter, covers a bit of this and
+      devfs under it's USB devices.  It leaves a lot to be desired though,
+      see:
+http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/usb-disks.html
+      It may be better to flesh out that section a bit more.  Add the
+      word "camera" to it so that others can easily notice.</para>
+  </sect1>
+
+  <sect1>
+    <title>Linux EXT File System</title>
+
+    <para>Probably NOT as useful as the other two, but it requires
+      knowledge of the existence of the tools.  Which are hidden in
+      the ports collection.  Most Linux guys would probably only use
+      Linux, BSD guys would be smarter and use NFS.</para>
+  </sect1>
+
+  <sect1>
+    <title>HFS</title>
+
+    <para>I think this is the file system used on Apple OSX.  There are
+      tools in the ports collection, and with Apple being a big
+      FreeBSD supporter and user of our technologies, surely there
+      is enough cross over to cover this?</para>
+  </sect1>
+  -->
+
+</chapter>