path: root/el_GR.ISO8859-7/books/handbook/filesystems/chapter.sgml

<!--

  Ôï Åã÷åéñßäéï ôïõ FreeBSD: ÓõóôÞìáôá Áñ÷åßùí

  The FreeBSD Greek Documentation Project

  $FreeBSD$

  %SOURCE%	en_US.ISO8859-1/books/handbook/filesystems/chapter.sgml
  %SRCID%	1.10

-->

<chapter id="filesystems">
  <chapterinfo>
    <authorgroup>
      <author>
	<firstname>Tom</firstname>
	<surname>Rhodes</surname>
	<contrib>ÃñÜöçêå áðü ôïí </contrib>
      </author>
    </authorgroup>
  </chapterinfo>

  <title>ÕðïóôÞñéîç ÓõóôçìÜôùí Áñ÷åßùí</title>

  <sect1 id="filesystems-synopsis">
    <title>Óýíïøç</title>

    <indexterm><primary>File Systems</primary></indexterm>
    <indexterm>
      <primary>File Systems Support</primary>
      <see>File Systems</see>
    </indexterm>

    <para>Ôá óõóôÞìáôá áñ÷åßùí áðïôåëïýí áíáðüóðáóôï ôìÞìá êÜèå ëåéôïõñãéêïý
      óõóôÞìáôïò.  ÅðéôñÝðïõí óôïõò ÷ñÞóôåò íá äçìéïõñãïýí êáé íá áðïèçêåýïõí
      áñ÷åßá, ðáñÝ÷ïõí ðñüóâáóç óå äåäïìÝíá, êáé öõóéêÜ áîéïðïéïýí ôïõò
      óêëçñïýò äßóêïõò.  ÄéáöïñåôéêÜ ëåéôïõñãéêÜ óõóôÞìáôá ÷ñçóéìïðïéïýí
      óõíÞèùò äéáöïñåôéêÜ åããåíÞ óõóôÞìáôá áñ÷åßùí.  Ôï óýóôçìá áñ÷åßùí ôïõ
      &os; åßíáé ôï Fast File System Þ <acronym>FFS</acronym>, ôï
      ïðïßï ðñïÞëèå áðü ôï áñ÷éêü óýóôçìá áñ÷åßùí ôïõ Unix&trade;, ãíùóôü
      åðßóçò êáé ùò <acronym>UFS</acronym>.  Áõôü åßíáé êáé ôï åããåíÝò
      óýóôçìá áñ÷åßùí ôïõ &os;, ôï ïðïßï ÷ñçóéìïðïéåßôáé óôïõò óêëçñïýò
      äßóêïõò êáé ðñïóöÝñåé ðñüóâáóç óôá äåäïìÝíá.</para>

    <para>Ôï &os; ðñïóöÝñåé åðßóçò ðëçèþñá äéáöïñåôéêþí óõóôçìÜôùí áñ÷åßùí,
      þóôå íá ðáñÝ÷åé ôïðéêÞ ðñüóâáóç óå äåäïìÝíá ðïõ Ý÷ïõí äçìéïõñãçèåß áðü
      Üëëá ëåéôïõñãéêÜ óõóôÞìáôá, ð.÷.&nbsp;äåäïìÝíá ðïõ âñßóêïíôáé óå ôïðéêÜ
      <acronym>USB</acronym> áðïèçêåõôéêÜ ìÝóá, ïäçãïýò flash, êáé óêëçñïýò
      äßóêïõò.  ÕðÜñ÷åé åðßóçò õðïóôÞñéîç ãéá Üëëá, ìç-åããåíÞ óõóôÞìáôá
      áñ÷åßùí, üðùò ôï Extended File System (<acronym>EXT</acronym>) ôïõ
      &linux; êáèþò êáé ôï óýóôçìá Z File System (<acronym>ZFS</acronym>) ôçò
      &sun;.</para>

    <para>Ôï &os; ðáñÝ÷åé äéáöïñåôéêü åðßðåäï õðïóôÞñéîçò ãéá êÜèå óýóôçìá
      áñ÷åßùí.  Ãéá ïñéóìÝíá èá ÷ñåéáóôåß íá öïñôùèåß êÜðïéï Üñèñùìá óôïí
      ðõñÞíá, åíþ ãéá Üëëá èá ðñÝðåé íá åãêáôáóôáèïýí êÜðïéá åñãáëåßá.
      Ôï êåöÜëáéï áõôü Ý÷åé ó÷åäéáóôåß íá âïçèÞóåé ôïõò ÷ñÞóôåò ôïõ &os; íá
      áðïêôÞóïõí ðñüóâáóç óå Üëëá óõóôÞìáôá áñ÷åßùí óôï óýóôçìá ôïõò,
      îåêéíþíôáò áðü ôï Æ File System ôçò &sun;.</para>

    <para>Áöïý äéáâÜóåôå áõôü ôï êåöÜëáéï, èá ãíùñßæåôå:</para>

    <itemizedlist>
      <listitem>
	<para>Ôç äéáöïñÜ ìåôáîý ôùí åããåíþí êáé ôùí õðïóôçñéæüìåíùí
	  óõóôçìÜôùí áñ÷åßùí.</para>
      </listitem>

      <listitem>
	<para>Ðïéá óõóôÞìáôá áñ÷åßùí õðïóôçñßæïíôáé áðü ôï &os;.</para>
      </listitem>

      <listitem>
	<para>Ðùò íá åíåñãïðïéÞóåôå, íá ñõèìßóåôå, íá áðïêôÞóåôå ðñüóâáóç êáé
	  íá ÷ñçóéìïðïéÞóåôå ìç-åããåíÞ óõóôÞìáôá áñ÷åßùí.</para>
      </listitem>
    </itemizedlist>

    <para>Ðñéí äéáâÜóåôå áõôü ôï êåöÜëáéï, èá ðñÝðåé:</para>

    <itemizedlist>
      <listitem>
	<para>Íá êáôáíïåßôå âáóéêÝò Ýííïéåò ôïõ &unix; êáé ôïõ &os;
	  (<xref linkend="basics">).</para>
      </listitem>

      <listitem>
	<para>Íá åßóôå åîïéêåéùìÝíïò ìå ôéò âáóéêÝò äéáäéêáóßåò ñýèìéóçò êáé
	  åãêáôÜóôáóçò ðñïóáñìïóìÝíïõ ðõñÞíá
	  (<xref linkend="kernelconfig">).</para>
      </listitem>

      <listitem>
	<para>Íá áéóèÜíåóôå Üíåôá ìå ôçí åãêáôÜóôáóç åöáñìïãþí ôñßôïõ
	  êáôáóêåõáóôÞ óôï &os; (<xref linkend="ports">).</para>
      </listitem>

      <listitem>
	<para>Íá åßóôå åîïéêåéùìÝíïò ìå ôïõò äßóêïõò, ôá ìÝóá
	  áðïèÞêåõóçò, êáé ôá áíôßóôïé÷á ïíüìáôá óõóêåõþí óôï
	  &os; (<xref linkend="disks">).</para>
      </listitem>
    </itemizedlist>
  </sect1>

  <sect1 id="filesystems-zfs">
    <title>Ôï Óýóôçìá Áñ÷åßùí Z (ZFS)</title>

    <para>Ôï óýóôçìá áñ÷åßùí Z, áíáðôý÷èçêå áðü ôçí &sun;, êáé åßíáé ìéá íÝá
      ôå÷íïëïãßá ðïõ ó÷åäéÜóôçêå ãéá íá ðáñÝ÷åé áðïèÞêåõóç ìÝóù ôçò ìåèüäïõ
      pool.  Áõôü óçìáßíåé üôé üëïò ï åëåýèåñïò ÷þñïò äéáôßèåôáé ùò
      áðüèåìá, êáé äéáíÝìåôáé äõíáìéêÜ óå êÜèå óýóôçìá áñ÷åßùí áíÜëïãá ìå ôéò
      áíÜãêåò áðïèÞêåõóçò äåäïìÝíùí.  ¸÷åé åðßóçò ó÷åäéáóôåß ãéá ôç ìÝãéóôç
      áêåñáéüôçôá äåäïìÝíùí êáé õðïóôçñßæåé óôéãìéüôõðá (snapshots) äåäïìÝíùí,
      ðïëëáðëÜ áíôßãñáöá êáé áèñïßóìáôá åëÝã÷ïõ äåäïìÝíùí (checksums).  ¸÷åé
      áêüìá ðñïóôåèåß Ýíá íÝï ìïíôÝëï ãéá ôç äéáôÞñçóç áíôéãñÜöùí ôùí
      äåäïìÝíùí, ãíùóôü ùò <acronym>RAID</acronym>-Z.  Ôï ìïíôÝëï
      <acronym>RAID</acronym>-Z åßíáé ðáñüìïéï ìå ôï
      <acronym>RAID</acronym>5 áëëÜ åßíáé ó÷åäéáóìÝíï íá ðáñÝ÷åé ðñïóôáóßá
      ôùí äåäïìÝíùí êáôÜ ôçí åããñáöÞ ôïõò.</para>

    <sect2>
      <title>Âåëôéóôïðïßçóç ôïõ ZFS</title>

      <para>Ôï õðïóýóôçìá <acronym>ZFS</acronym> ÷ñçóéìïðïéåß áñêåôïýò ðüñïõò
	ôïõ óõóôÞìáôïò.  Âåëôéóôïðïéþíôáò ôéò ñõèìßóåéò ôïõ óõóôÞìáôïò óáò, èá
	åðéôý÷åôå ôç ìÝãéóôç áðüäïóç óôçí êáèçìåñéíÞ ÷ñÞóç.  Êáèþò ôï
	<acronym>ZFS</acronym> åßíáé áêüìá óå ðåéñáìáôéêü óôÜäéï óôï &os;,
	áõôü ßóùò áëëÜîåé ìåëëïíôéêÜ.  Ùóôüóï, ãéá ôçí þñá, óõíßóôáôáé íá
	áêïëïõèÞóåôå ôá ðáñáêÜôù âÞìáôá:</para>

      <sect3>
	<title>ÌíÞìç</title>

	<para>Ôï óõíïëéêü ìÝãåèïò ìíÞìçò ôïõ óõóôÞìáôïò ðñÝðåé íá åßíáé
	  ôïõëÜ÷éóôïí Ýíá gigabyte, åíþ ôï óõíéóôþìåíï ìÝãåèïò åßíáé äýï
	  gigabytes Þ êáé ðåñéóóüôåñï.  Óå üëá ôá ðáñáäåßãìáôá ðïõ öáßíïíôáé
	  åäþ, ôï óýóôçìá Ý÷åé Ýíá gigabyte ìíÞìçò êáé Ý÷ïõìå åðßóçò
	  âåëôéóôïðïéÞóåé ôéò ñõèìßóåéò ôïõ.</para>

	<para>ÏñéóìÝíïé ÷ñÞóôåò öáßíåôáé íá ôá êáôáöÝñíïõí êáé ìå ëéãüôåñï
	  áðü Ýíá gigabyte ìíÞìçò, áëëÜ ìå ôÝôïéïõò ðåñéïñéóìïýò öõóéêÞò
	  ìíÞìçò, åßíáé áñêåôÜ ðéèáíü íá äçìéïõñãçèåß panic êÜôù áðü âáñý
	  öïñôßï åñãáóßáò, åîáéôßáò åîÜíôëçóçò ôçò.</para>
      </sect3>

      <sect3>
	<title>Ñýèìéóç ôïõ ÐõñÞíá</title>

	<para>Óõíßóôáôáé íá áöáéñÝóåôå ôá ðñïãñÜììáôá ïäÞãçóçò êáé ôéò
	  åðéëïãÝò ðïõ äåí ÷ñçóéìïðïéåßôå áðü ôï áñ÷åßï ñõèìßóåùí ôïõ
	  ðõñÞíá.  Êáèþò ïé ðåñéóóüôåñïé ïäçãïß óõóêåõþí äéáôßèåíôáé åðßóçò
	  êáé óå ìïñöÞ áñèñùìÜôùí, ìðïñåßôå áðëÜ íá ôïõò öïñôþóåôå
	  ÷ñçóéìïðïéþíôáò ôï áñ÷åßï
	  <filename>/boot/loader.conf</filename>.</para>

	<para>Ïé ÷ñÞóôåò ôçò áñ÷éôåêôïíéêÞò &i386; èá ðñÝðåé íá ðñïóèÝóïõí ôçí
	  ðáñáêÜôù åðéëïãÞ óôï áñ÷åßï ñõèìßóåùí ôïõ ðõñÞíá ôïõò, íá ôïí
	  åðáíáìåôáãëùôôßóïõí êáé íá åðáíåêêéíÞóïõí ôï óýóôçìá ôïõò:</para>

	<programlisting>options 	KVA_PAGES=512</programlisting>

	<para>Ç åðéëïãÞ áõôÞ èá äéåõñýíåé ôçí ðåñéï÷Þ äéåõèýíóåùí ôïõ ðõñÞíá,
	  åðéôñÝðïíôáò Ýôóé ôçí áýîçóç ôéìÞò ôçò ñõèìéóôéêÞò ìåôáâëçôÞò
	  <varname>vm.kvm_size</varname> ðÝñá áðü ôï ôñÝ÷ïí üñéï ôïõ
	  1&nbsp;GB (2&nbsp;GB ãéá ðõñÞíåò <acronym>PAE</acronym>).  Ãéá íá
	  âñåßôå ôçí êáôáëëçëüôåñç ôéìÞ ãéá áõôÞ ôçí åðéëïãÞ, äéáéñÝóôå ôï
	  åðéèõìçôü ìÝãåèïò ôçò ðåñéï÷Þò äéåõèýíóåùí ìå ôï ôÝóóåñá (4).  Óôçí
	  ðåñßðôùóç áõôÞ, Ý÷ïõìå <literal>512</literal> ãéá ìÝãåèïò
	  2&nbsp;GB.</para>
      </sect3>

      <sect3>
	<title>Ñõèìßóåéò óôéò ÌåôáâëçôÝò ôïõ Loader</title>

	<para>Èá ðñÝðåé íá áõîçèåß ç ðåñéï÷Þ äéåõèýíóåùí
	  <devicename>kmem</devicename> óå üëåò ôéò áñ÷éôåêôïíéêÝò ôïõ &os;.
	  Óôï äïêéìáóôéêü ìáò óýóôçìá, ìå Ýíá gigabyte öõóéêÞò ìíÞìçò,
	  åß÷áìå åðéôõ÷çìÝíï áðïôÝëåóìá ÷ñçóéìïðïéþíôáò ôéò áêüëïõèåò
	  åðéëïãÝò óôï áñ÷åßï <filename>/boot/loader.conf</filename> êáé
	  åðáíåêêéíþíôáò ôï óýóôçìá ìáò:</para>

	<programlisting>vm.kmem_size="330M"
vm.kmem_size_max="330M"
vfs.zfs.arc_max="40M"
vfs.zfs.vdev.cache.size="5M"</programlisting>

	<para>Ãéá áíáëõôéêüôåñåò ñõèìßóåéò ó÷åôéêÜ ìå ôçí âåëôéóôïðïßçóç ôïõ
	  ZFS, äåßôå ôï <ulink
	    url="http://wiki.freebsd.org/ZFSTuningGuide"></ulink>.</para>
      </sect3>
    </sect2>

    <sect2>
      <title>×ñçóéìïðïéþíôáò ôï <acronym>ZFS</acronym></title>

      <para>ÕðÜñ÷åé Ýíáò ìç÷áíéóìüò åêêßíçóçò ðïõ åðéôñÝðåé óôï &os; íá
	ðñïóáñôÞóåé <acronym>ZFS</acronym> pools êáôÜ ôç äéÜñêåéá ôçò
	åêêßíçóçò ôïõ óõóôÞìáôïò.  Ãéá íá ôïí ñõèìßóåôå, åêôåëÝóôå ôéò
	áêüëïõèåò åíôïëÝò:</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>Ôï õðüëïéðï áõôïý ôïõ êåéìÝíïõ õðïèÝôåé üôé Ý÷åôå äéáèÝóéìïõò
	ôñåéò <acronym>SCSI</acronym> äßóêïõò, êáé üôé ôá ïíüìáôá óõóêåõþí
	ôïõò åßíáé <devicename><replaceable>da0</replaceable></devicename>,
	<devicename><replaceable>da1</replaceable></devicename> êáé
	<devicename><replaceable>da2</replaceable></devicename>.
	¼óïé äéáèÝôïõí äßóêïõò <acronym>IDE</acronym> èá
	ðñÝðåé íá ÷ñçóéìïðïéÞóïõí óõóêåõÝò ôïõ ôýðïõ
	<devicename><replaceable>ad</replaceable></devicename>
	áíôß ãéá ôéò áíôßóôïé÷åò <acronym>SCSI</acronym>.</para>

      <sect3>
	<title>Pool ìå ¸íá Ìüíï Äßóêï</title>

	<para>Ãéá ôçí äçìéïõñãßá åíüò <acronym>ZFS</acronym> pool ìå Ýíá
	  ìüíï äßóêï (÷ùñßò äõíáôüôçôá áíï÷Þò óöáëìÜôùí), ÷ñçóéìïðïéÞóôå ôçí
	  åíôïëÞ <command>zpool</command>:</para>

	<screen>&prompt.root; <userinput>zpool create example /dev/da0</userinput></screen>

	<para>Ãéá íá äåßôå ôï íÝï pool, åîåôÜóôå ôçí Ýîïäï ôçò åíôïëÞò
	  <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>Ç Ýîïäïò áõôÞ äåß÷íåé êáèáñÜ üôé ôï <literal>example</literal>
	  pool ü÷é ìüíï Ý÷åé äçìéïõñãçèåß, áëëÜ Ý÷åé åðßóçò
	  <emphasis>ðñïóáñôçèåß</emphasis> êéüëáò.  Åßíáé åðßóçò äéáèÝóéìï ùò
	  êáíïíéêü óýóôçìá áñ÷åßùí, ìðïñåßôå íá äçìéïõñãÞóåôå áñ÷åßá óå áõôü,
	  êáé Üëëïé ÷ñÞóôåò ìðïñïýí åðßóçò íá ôï äïõí, üðùò öáßíåôáé óôï
	  ðáñáêÜôù ðáñÜäåéãìá:</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>Äõóôõ÷þò áõôü ôï pool äåí ÷ñçóéìïðïéåß êÜðïéï áðü ôá
	  ðëåïíåêôÞìáôá ôïõ <acronym>ZFS</acronym>.  ÄçìéïõñãÞóôå Ýíá óýóôçìá
	  áñ÷åßùí óå áõôü ôï pool êáé åíåñãïðïéÞóôå óå áõôü ôç
	  óõìðßåóç:</para>

	<screen>&prompt.root; <userinput>zfs create example/compressed</userinput>
&prompt.root; <userinput>zfs set compression=gzip example/compressed</userinput></screen>

	<para>Ôï óýóôçìá áñ÷åßùí <literal>example/compressed</literal>
	  åßíáé ðëÝïí Ýíá óõìðéåóìÝíï <acronym>ZFS</acronym> óýóôçìá.
	  ÄïêéìÜóôå íá áíôéãñÜøåôå ìåñéêÜ ìåãÜëá áñ÷åßá óå áõôü, áðåõèåßáò
	  óôïí êáôÜëïãï
	  <filename class="directory">/example/compressed</filename>.</para>

	<para>Ìðïñåßôå ôþñá íá áðåíåñãïðïéÞóåôå ôç óõìðßåóç ãñÜöïíôáò:</para>

	<screen>&prompt.root; <userinput>zfs set compression=off example/compressed</userinput></screen>

	<para>Ãéá íá áðïðñïóáñôÞóåôå ôï óýóôçìá áñ÷åßùí, åêôåëÝóôå ôçí
	  áêüëïõèç åíôïëÞ êáé åðáëçèåýóôå ôï áðïôÝëåóìá ìÝóù ôïõ âïçèçôéêïý
	  ðñïãñÜììáôïò <command>df</command>:</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>ÐñïóáñôÞóôå îáíÜ ôï óýóôçìá áñ÷åßùí, þóôå íá åßíáé êáé ðÜëé
	  ðñïóâÜóéìï, êáé åðáëçèåýóôå ôï ÷ñçóéìïðïéþíôáò üðùò êáé ðñéí, ôçí
	  åíôïëÞ <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>Ìðïñåßôå åðßóçò íá äåßôå ôï pool êáé ôï óýóôçìá áñ÷åßùí
	  åîåôÜæïíôáò ôçí Ýîïäï ôçò åíôïëÞò <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>¼ðùò ðáñáôçñïýìå, ôï óýóôçìá áñ÷åßùí <acronym>ZFS</acronym>
	  ìðïñåß íá ÷ñçóéìïðïéçèåß ùò êïéíü óýóôçìá áñ÷åßùí ìåôÜ ôç
	  äçìéïõñãßá ôïõ.  Ùóôüóï, äéáèÝôåé ðïëëÝò áêüìá ëåéôïõñãßåò.  Óôï
	  ðáñáêÜôù ðáñÜäåéãìá äçìéïõñãïýìå Ýíá íÝï óýóôçìá áñ÷åßùí, ôï
	  <literal>data</literal>.  èá áðïèçêåýóïõìå óçìáíôéêÜ äåäïìÝíá óå
	  áõôü, êáé Ýôóé ôï ñõèìßæïõìå þóôå íá êñáôÜåé äýï áíôßãñáöá áðü
	  êÜèå ìðëïê äåäïìÝíùí:</para>

	<screen>&prompt.root; <userinput>zfs create example/data</userinput>
&prompt.root; <userinput>zfs set copies=2 example/data</userinput></screen>

	<para>Ìðïñïýìå ôþñá íá äïýìå ôá äåäïìÝíá êáé ôçí êáôáíÜëùóç ÷þñïõ
	  äßíïíôáò îáíÜ ôçí åíôïëÞ <command>df</command>:</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>ÐáñáôçñÞóôå üôé êÜèå óýóôçìá áñ÷åßùí óôï pool äåß÷íåé ôï ßäéï
	  ìÝãåèïò äéáèÝóéìïõ ÷þñïõ.  Áõôüò åßíáé êáé ï ëüãïò ðïõ
	  ÷ñçóéìïðïéïýìå ôçí åíôïëÞ <command>df</command> óå üëá ôá
	  ðáñáäåßãìáôá, ãéá íá äåßîïõìå üôé ôá óõóôÞìáôá áñ÷åßùí
	  ÷ñçóéìïðïéïýí ìüíï ôï ÷þñï ðïõ ÷ñåéÜæïíôáé êáé üôé üëá ìïéñÜæïíôáé
	  ôïí ßäéï ÷þñï (ôï êïéíü÷ñçóôï áðüèåìá &mdash; pool).  Óôï óýóôçìá
	  áñ÷åßùí <acronym>ZFS</acronym> Ýííïéåò üðùò ïé ôüìïé (volumes) êáé
	  ïé êáôáôìÞóåéò (partitions) äåí Ý÷ïõí íüçìá.  Áíôßèåôá, ðïëëÜ
	  óõóôÞìáôá áñ÷åßùí ìïéñÜæïíôáé ôïí ßäéï ÷þñï, ôï pool.  Ìðïñåßôå íá
	  êáôáñãÞóåôå ôï óýóôçìá áñ÷åßùí êáé êáôüðéí ôï ßäéï ôï pool üôáí
	  äåí ôá ÷ñåéÜæåóôå ðëÝïí:</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>Ïé óêëçñïß äßóêïé ìå ôïí êáéñü ÷áëÜíå, åßíáé áíáðüöåõêôï.
	  ¼ôáí Ýíáò äßóêïò ÷áëÜóåé, ôá äåäïìÝíá ôïõ ÷Üíïíôáé.  Ìéá ìÝèïäïò
	  ãéá íá áðïöýãïõìå ôçí áðþëåéá äåäïìÝíùí åîáéôßáò åíüò ÷áëáóìÝíïõ
	  äßóêïõ åßíáé íá äçìéïõñãÞóïõìå ìéá óõóôïé÷ßá
	  <acronym>RAID</acronym>.  Ôá pools ôïõ <acronym>ZFS</acronym> Ý÷ïõí
	  ó÷åäéáóèåß þóôå íá õðïóôçñßæïõí áõôü ôï ÷áñáêôçñéóôéêü.
	  Ç ëåéôïõñãßá áõôÞ áíáëýåôáé óôçí åðüìåíç åíüôçôá.</para>
      </sect3>

      <sect3>
	<title><acronym>ZFS</acronym> RAID-Z</title>

	<para>¼ðùò áíáöÝñáìå ðñïçãïõìÝíùò, ç åíüôçôá áõôÞ ðñïûðïèÝôåé üôé
	  ÷ñçóéìïðïéïýìå ôñåéò óõóêåõÝò
	  <acronym>SCSI</acronym> ìå ïíüìáôá óõóêåõþí
	  <devicename>da0</devicename>, <devicename>da1</devicename> êáé
	  <devicename>da2</devicename>.  Ãéá íá äçìéïõñãÞóïõìå Ýíá pool ôýðïõ
	  <acronym>RAID</acronym>-Z, åêôåëïýìå ôçí áêüëïõèç åíôïëÞ:</para>

	<screen>&prompt.root; <userinput>zpool create storage raidz da0 da1 da2</userinput></screen>

	<note>
	  <para>Ç &sun; óõíéóôÜ íá ÷ñçóéìïðïéïýíôáé áðü ôñåéò ùò åííéÜ
	    óõóêåõÝò óå óõóôïé÷ßåò ôýðïõ <acronym>RAID</acronym>-Z.
	    Áí ÷ñåéÜæåôáé íá äçìéïõñãÞóåôå Ýíá pool ìå ðåñéóóüôåñïõò áðü
	    äÝêá äßóêïõò, åßíáé ðñïôéìüôåñï íá ôï ÷ùñßóåôå óå ïìÜäåò áðü
	    ìéêñüôåñá <acronym>RAID</acronym>-Z pools.  Áí äéáèÝôåôå ìüíï
	    äýï äßóêïõò áëëÜ ÷ñåéÜæåóôå ôçí äõíáôüôçôá áíï÷Þò óöáëìÜôùí,
	    ßóùò åßíáé êáëýôåñï íá ÷ñçóéìïðïéÞóåôå Ýíá
	    <acronym>ZFS</acronym> mirror.  Äåßôå ôç óåëßäá manual ôïõ
	    &man.zpool.8; ãéá ðåñéóóüôåñåò ëåðôïìÝñåéåò.</para>
	</note>

	<para>Èá äçìéïõñãçèåß ôï <literal>storage</literal> zpool.  Ìðïñåßôå
	  íá åðáëçèåýóåôå ôï áðïôÝëåóìá ÷ñçóéìïðïéþíôáò, üðùò êáé
	  ðñïçãïõìÝíùò, ôéò åíôïëÝò &man.mount.8; êáé &man.df.1;.  Èá
	  ìðïñïýóáìå íá ÷ñçóéìïðïéÞóïõìå ðåñéóóüôåñïõò äßóêïõò, ðñïóèÝôïíôáò
	  ôá ïíüìáôá óõóêåõþí ôïõò óôï ôÝëïò ôçò ðáñáðÜíù ëßóôáò.
	  ÄçìéïõñãÞóôå Ýíá íÝï óýóôçìá áñ÷åßùí óôï pool, ôï ïðïßï èá
	  ïíïìÜæåôáé <literal>home</literal> êáé üðïõ èá áðïèçêåýïíôáé ôåëéêÜ
	  ôá áñ÷åßá ôùí ÷ñçóôþí:</para>

	<screen>&prompt.root; <userinput>zfs create storage/home</userinput></screen>

	<para>Ìðïñïýìå ôþñá íá åíåñãïðïéÞóïõìå ôçí óõìðßåóç êáé íá êñáôÜìå
	  åðéðëÝïí áíôßãñáöá ôùí êáôáëüãùí êáé ôùí äåäïìÝíùí ôùí ÷ñçóôþí.
	  ¼ðùò êáé ðñïçãïõìÝíùò, ìðïñïýìå íá ôï åðéôý÷ïõìå ÷ñçóéìïðïéþíôáò
	  ôéò ðáñáêÜôù åíôïëÝò:</para>

	<screen>&prompt.root; <userinput>zfs set copies=2 storage/home</userinput>
&prompt.root; <userinput>zfs set compression=gzip storage/home</userinput></screen>

	<para>Ãéá íá ãßíåé áõôüò ï íÝïò êáôÜëïãïò ôùí ÷ñçóôþí, áíôéãñÜøôå ôá
	  äåäïìÝíá ôïõò óå áõôüí êáé äçìéïõñãÞóôå ôïõò êáôÜëëçëïõò
	  óõìâïëéêïýò äåóìïýò:</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>Ôá äåäïìÝíá ôùí ÷ñçóôþí èá áðïèçêåýïíôáé ôþñá óôï íÝï óýóôçìá
	  áñ÷åßùí <filename class="directory">/storage/home</filename>.
	  Ãéá íá ôï åðáëçèåýóåôå, äçìéïõñãÞóôå Ýíá íÝï ÷ñÞóôç êáé åéóÝëèåôå
	  óôï óýóôçìá ìå ôï íÝï ëïãáñéáóìü.</para>

	<para>ÄïêéìÜóôå íá äçìéïõñãÞóåôå Ýíá óôéãìéüôõðï (snapshot) óôï
	  ïðïßï èá ìðïñåßôå íá åðáíÝëèåôå áñãüôåñá:</para>

	<screen>&prompt.root; <userinput>zfs snapshot storage/home@08-30-08</userinput></screen>

	<para>Óçìåéþóôå üôé ç åðéëïãÞ äçìéïõñãßáò óôéãìéüôõðïõ ëåéôïõñãåß
	  ìüíï óå ðñáãìáôéêü óýóôçìá áñ÷åßùí, êáé ü÷é óå êÜðïéï ìåìïíùìÝíï
	  êáôÜëïãï Þ áñ÷åßï.  Ï ÷áñáêôÞñáò <literal>@</literal>
	  ÷ñçóéìïðïéåßôáé ùò äéá÷ùñéóôéêü ìåôáîý ôïõ óõóôÞìáôïò áñ÷åßùí êáé
	  ôïõ ïíüìáôïò ôüìïõ.  Áí êáôáóôñáöåß ï êáôÜëïãïò äåäïìÝíùí êÜðïéïõ
	  ÷ñÞóôç áðïêáôáóôÞóôå ôïí ìå ôçí åíôïëÞ:</para>

	<screen>&prompt.root; <userinput>zfs rollback storage/home@08-30-08</userinput></screen>

	<para>Ãéá íá äåßôå ìéá ëßóôá ôùí äéáèÝóéìùí óôéãìéüôõðùí, åêôåëÝóôå
	  ôçí åíôïëÞ <command>ls</command> óôïí êáôÜëïãï
	  <filename class="directory">.zfs/snapshot</filename> ôïõ óõóôÞìáôïò
	  áñ÷åßùí.  Ãéá ðáñÜäåéãìá, ãéá íá äåßôå ôï óôéãìéüôõðï ðïõ
	  äçìéïõñãÞóáìå ðñïçãïõìÝíùò, åêôåëÝóôå ôçí ðáñáêÜôù åíôïëÞ:</para>

	<screen>&prompt.root; <userinput>ls /storage/home/.zfs/snapshot</userinput></screen>

	<para>Åßíáé äõíáôüí íá ãñÜøåôå êÜðïéï script ðïõ íá äçìéïõñãåß
	  ìçíéáßá óôéãìéüôõðá ôùí äåäïìÝíùí ôùí ÷ñçóôþí.  Ùóôüóï, ìå ôçí
	  ðÜñïäï ôïõ ÷ñüíïõ, ôá óôéãìéüôõðá èá êáôáíáëþóïõí ìåãÜëï ðïóïóôü
	  ôïõ ÷þñïõ óôï äßóêï.  Ìðïñåßôå íá äéáãñÜøåôå ôï ðñïçãïýìåíï
	  óôéãìéüôõðï ÷ñçóéìïðïéþíôáò ôçí ðáñáêÜôù åíôïëÞ:</para>

	<screen>&prompt.root; <userinput>zfs destroy storage/home@08-30-08</userinput></screen>

	<para>Äåí õðÜñ÷åé ëüãïò, ìåôÜ áðü üëåò áõôÝò ôéò äïêéìÝò, íá
	  êñáôÞóïõìå ôï <filename class="directory">/storage/home</filename>
	  óôçí ðáñïýóá êáôÜóôáóç ôïõ.  ÌåôáôñÝøôå ôï óôï ðñáãìáôéêü óýóôçìá
	  áñ÷åßùí <filename class="directory">/home</filename>:</para>

	<screen>&prompt.root; <userinput>zfs set mountpoint=/home storage/home</userinput></screen>

	<para>×ñçóéìïðïéþíôáò ôéò åíôïëÝò <command>df</command> êáé
	  <command>mount</command> èá äïýìå üôé ôï óýóôçìá ÷åéñßæåôáé ðëÝïí
	  áõôü ôï óýóôçìá áñ÷åßùí ùò ôï ðñáãìáôéêü
	  <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       26320512       0 26320512     0%    /storage
storage/home  26320512       0 26320512     0%    /home</screen>

	<para>Åäþ ïëïêëçñþíåôáé ç ñýèìéóç ôïõ <acronym>RAID</acronym>-Z.
	  Ãéá íá äÝ÷åóôå áíáöïñÝò êáôÜóôáóçò ó÷åôéêÜ ìå ôá óõóôÞìáôá
	  áñ÷åßùí êáôÜ ôç íõêôåñéíÞ åêôÝëåóç ôïõ &man.periodic.8;, äþóôå ôçí
	  ðáñáêÜôù åíôïëÞ:</para>

	<screen>&prompt.root; <userinput>echo 'daily_status_zfs_enable="YES"' &gt;&gt; /etc/periodic.conf</userinput></screen>
      </sect3>

      <sect3>
	<title>ÁíÜêôçóç ôïõ <acronym>RAID</acronym>-Z</title>

	<para>ÊÜèå ëïãéóìéêü <acronym>RAID</acronym> Ý÷åé ìéá ìÝèïäï ãéá
	  åðßâëåøç ôçò êáôÜóôáóÞò ôïõ, êáé ôï <acronym>ZFS</acronym> äåí
	  áðïôåëåß åîáßñåóç.  Ìðïñåßôå íá äåßôå ôçí êáôÜóôáóç ôùí óõóêåõþí
	  ôïõ <acronym>RAID</acronym>-Z ÷ñçóéìïðïéþíôáò ôçí áêüëïõèç
	  åíôïëÞ:</para>

	<screen>&prompt.root; <userinput>zpool status -x</userinput></screen>

	<para>Áí üëá ôá pools åßíáé óå õãéÞ êáôÜóôáóç, èá ðÜñåôå ôï áêüëïõèï
	  ìÞíõìá:</para>

	<screen>all pools are healthy</screen>

	<para>Áí õðÜñ÷åé êÜðïéï ðñüâëçìá, ð.÷. êÜðïéïò äßóêïò Ý÷åé âãåé
	  åêôüò ëåéôïõñãßáò, èá äåßôå ôçí ðåñéãñáöÞ ôçò êáôÜóôáóçò óå
	  Ýíá ìÞíõìá üðùò ôï ðáñáêÜôù:</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
	    da2     ONLINE       0     0     0

errors: No known data errors</screen>

	<para>Ôï ðáñáðÜíù äåß÷íåé üôé ç óõóêåõÞ ôÝèçêå åêôüò ëåéôïõñãßáò
	  áðü ôïí äéá÷åéñéóôÞ.  Áõôü åßíáé áëÞèåéá ãéá ôï óõãêåêñéìÝíï
	  ðáñÜäåéãìá.  Ãéá íá ôåèåß ï äßóêïò åêôüò, ÷ñçóéìïðïéÞèçêå ç
	  ðáñáêÜôù åíôïëÞ:</para>

	<screen>&prompt.root; <userinput>zpool offline storage da1</userinput></screen>

	<para>Ìðïñïýìå ôþñá íá áíôéêáôáóôÞóïõìå ôï äßóêï
	  <devicename>da1</devicename> ìåôÜ ôçí áðåíåñãïðïßçóç ôïõ
	  óõóôÞìáôïò.  ¼ôáí ôï óýóôçìá åðáíÝëèåé óå ëåéôïõñãßá, ìðïñïýìå íá
	  ÷ñçóéìïðïéÞóïõìå ôçí áêüëïõèç åíôïëÞ ãéá íá åíçìåñþóïõìå ôï
	  óýóôçìá ãéá ôçí áíôéêáôÜóôáóç ôïõ äßóêïõ:</para>

	<screen>&prompt.root; <userinput>zpool replace storage da1</userinput></screen>

	<para>Áðü åäþ, ìðïñïýìå íá åëÝãîïõìå îáíÜ ôçí êáôÜóôáóç, áõôÞ ôç
	  öïñÜ ÷ùñßò ôçí åðéëïãÞ <option>-x</option>:</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
	    da2     ONLINE       0     0     0

errors: No known data errors</screen>

	<para>¼ðùò öáßíåôáé óôï ðáñÜäåéãìá, ôá ðÜíôá öáßíåôáé íá ëåéôïõñãïýí
	  öõóéïëïãéêÜ.</para>
      </sect3>

      <sect3>
	<title>ÅðáëÞèåõóç ÄåäïìÝíùí</title>

	<para>¼ðùò áíáöÝñáìå ðñïçãïõìÝíùò, ôï <acronym>ZFS</acronym>
	  ÷ñçóéìïðïéåß <literal>checksums</literal> (áèñïßóìáôá åëÝã÷ïõ) ãéá
	  íá åðáëçèåýóåé ôçí áêåñáéüôçôá ôùí áðïèçêåõìÝíùí äåäïìÝíùí.
	  Ôá áèñïßóìáôá åëÝã÷ïõ åíåñãïðïéïýíôáé áõôüìáôá êáôÜ ôçí äçìéïõñãßá
	  ôùí óõóôçìÜôùí áñ÷åßùí, êáé ìðïñïýí íá áðåíåñãïðïéçèïýí ìÝóù ôçò
	  åðüìåíçò åíôïëÞò:</para>

	<screen>&prompt.root; <userinput>zfs set checksum=off storage/home</userinput></screen>

	<para>Áõôü äåí åßíáé ãåíéêÜ êáëÞ éäÝá, êáèþò ôá checksums
	  êáôáëáìâÜíïõí åëÜ÷éóôï áðïèçêåõôéêü ÷þñï, êáé åßíáé ðïëý ðéï
	  ÷ñÞóéìï íá ôá Ý÷ïõìå åíåñãïðïéçìÝíá.  Åðßóçò äåí öáßíåôáé íá
	  ðñïêáëïýí êÜðïéá óçìáíôéêÞ êáèõóôÝñçóç Þ åðéâÜñõíóç.  Ìå ôá
	  checksums åíåñãïðïéçìÝíá, ìðïñïýìå íá æçôÞóïõìå áðü ôï
	  <acronym>ZFS</acronym> íá åëÝãîåé ôçí áêåñáéüôçôá ôùí äåäïìÝíùí
	  ÷ñçóéìïðïéþíôáò ôá ãéá åðáëÞèåõóç.  Ç äéáäéêáóßá áõôÞ åßíáé
	  ãíùóôÞ ùò <quote>scrubbing.</quote>  Ãéá íá åëÝãîåôå ôçí
	  áêåñáéüôçôá äåäïìÝíùí ôïõ pool <literal>storage</literal>,
	  ÷ñçóéìïðïéÞóôå ôçí ðáñáêÜôù åíôïëÞ:</para>

	<screen>&prompt.root; <userinput>zpool scrub storage</userinput></screen>

	<para>Ç äéáäéêáóßá áõôÞ ìðïñåß íá ðÜñåé áñêåôÞ þñá, áíÜëïãá ìå ôçí
	  ðïóüôçôá ôùí áðïèçêåõìÝíùí äåäïìÝíùí.  Åðßóçò ÷ñçóéìïðïéåß ðÜñá
	  ðïëý ôï äßóêï (<acronym>I/O</acronym>), ôüóï þóôå óå êÜèå
	  äåäïìÝíç óôéãìÞ ìðïñåß íá åêôåëåßôáé ìüíï ìéá ôÝôïéá äéáäéêáóßá.
	  ÌåôÜ ôçí ïëïêëÞñùóç ôïõ scrub, èá áíáíåùèåß êáé ç áíáöïñÜ
	  êáôÜóôáóçò, ôçí ïðïßá ìðïñåßôå íá äåßôå æçôþíôáò ôçí ìå ôçí
	  ðáñáêÜôù åíôïëÞ:</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
	    da2     ONLINE       0     0     0

errors: No known data errors</screen>

	<para>Óôï ðáñÜäåéãìá ìáò åìöáíßæåôáé êáé ç ÷ñïíéêÞ óôéãìÞ ðïõ
	  ïëïêëçñþèçêå ç åíôïëÞ scrub.  Ç äõíáôüôçôá áõôÞ ìáò åîáóöáëßæåé
	  áêåñáéüôçôá äåäïìÝíùí óå ìåãÜëï âÜèïò ÷ñüíïõ.</para>

	<para>ÕðÜñ÷ïõí ðïëëÝò áêüìá åðéëïãÝò ãéá ôï óýóôçìá áñ÷åßùí Æ.  Äåßôå
	  ôéò óåëßäåò manual &man.zfs.8; êáé &man.zpool.8;.</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>

<!--
     Local Variables:
     mode: sgml
     coding: iso-8859-7
     sgml-declaration: "../chapter.decl"
     sgml-indent-data: t
     sgml-omittag: nil
     sgml-always-quote-attributes: t
     sgml-parent-document: ("../book.sgml" "part" "chapter")
     End:
-->