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Date:      Fri, 11 Jan 2013 21:14:35 -0500 (EST)
From:      Diane Bruce <db@db.net>
To:        FreeBSD-gnats-submit@freebsd.org
Subject:   docs/175226: obsolete section on tapes in handbook
Message-ID:  <20130112021435.E120C1CCDF@night.db.net>
Resent-Message-ID: <201301120220.r0C2K0rk035818@freefall.freebsd.org>

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>Number:         175226
>Category:       docs
>Synopsis:       obsolete section on tapes in handbook
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-doc
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          doc-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Jan 12 02:20:00 UTC 2013
>Closed-Date:
>Last-Modified:
>Originator:     Diane Bruce
>Release:        FreeBSD 9.0-RELEASE amd64
>Organization:
Do I have to have any?
>Environment:
System: FreeBSD night.db.net 9.0-RELEASE FreeBSD 9.0-RELEASE #11: Sat Jun 30 08:32:31 EST 2012 root@night.db.net:/usr/obj/usr/src/sys/GENERIC amd64


	
>Description:
	
>How-To-Repeat:
	
>Fix:

	


Index: en_US.ISO8859-1/books/handbook/disks/chapter.xml
===================================================================
--- en_US.ISO8859-1/books/handbook/disks/chapter.xml	(revision 40568)
+++ en_US.ISO8859-1/books/handbook/disks/chapter.xml	(working copy)
@@ -2085,234 +2085,77 @@
 
     <indexterm><primary>tape media</primary></indexterm>
 
-    <para>The major tape media are the 4mm, 8mm, QIC, mini-cartridge
-      and DLT.</para>
+    <para>Tape technology has continued to evolve  but is less likely to be 
+      used in a modern system. Modern backup systems tend to use offsite
+      combined with local removable disk drive technologies. Nevertheless
+      FreeBSD will support any tape drive that uses SCSI such as LTO and
+      older devices such as DAT. There is limited support for SATA/USB tape
+      as well.
+      </para>
 
-    <sect2 id="backups-tapebackups-4mm">
-      <title>4mm (DDS: Digital Data Storage)</title>
+    <sect2 id="backups-tapebackups-sa0">
+      <title>Tape drives/serial access</title>
 
       <indexterm>
-	<primary>tape media</primary>
-	<secondary>DDS (4mm) tapes</secondary>
+	<primary>tape drives</primary>
       </indexterm>
-      <indexterm>
-	<primary>tape media</primary>
-	<secondary>QIC tapes</secondary>
-      </indexterm>
-      <para>4mm tapes are replacing QIC as the workstation backup
-	media of choice.  This trend accelerated greatly when Conner
-	purchased Archive, a leading manufacturer of QIC drives, and
-	then stopped production of QIC drives.  4mm drives are small
-	and quiet but do not have the reputation for reliability that
-	is enjoyed by 8mm drives.  The cartridges are less expensive
-	and smaller (3 x 2 x 0.5 inches, 76 x 51 x 12 mm) than 8mm
-	cartridges.  4mm, like 8mm, has comparatively short head life
-	for the same reason, both use helical scan.</para>
 
-      <para>Data throughput on these drives starts ~150&nbsp;kB/s,
-	peaking at ~500&nbsp;kB/s.  Data capacity starts at
-	1.3&nbsp;GB and ends at 2.0&nbsp;GB.  Hardware compression,
-	available with most of these drives, approximately doubles the
-	capacity.  Multi-drive tape library units can have 6 drives in
-	a single cabinet with automatic tape changing.  Library
-	capacities reach 240&nbsp;GB.</para>
-
-      <para>The DDS-3 standard now supports tape capacities up to
-	12&nbsp;GB (or 24&nbsp;GB compressed).</para>
-
-      <para>4mm drives, like 8mm drives, use helical-scan.  All the
-	benefits and drawbacks of helical-scan apply to both 4mm and
-	8mm drives.</para>
-
-      <para>Tapes should be retired from use after 2,000 passes or 100
-	full backups.</para>
+      <para>FreeBSD uses the sa(4) driver, providing <devicename>/dev/sa0</devicename>, 
+            <devicename>/dev/nsa0</devicename> and <devicename>/dev/esa0</devicename>.
+            In normal use only <devicename>/dev/sa0</devicename> is needed.
+            <devicename>/dev/nsa0</devicename> is the same
+            physical drive as <devicename>/dev/sa0</devicename> but does
+            not rewind the tape when a file is written to the tape and
+            this enables more than one backup to be done on a tape.
+            <devicename>/dev/esa0</devicename> Ejects the tape after
+            a close if applicable.
+      </para>
     </sect2>
 
-    <sect2 id="backups-tapebackups-8mm">
-      <title>8mm (Exabyte)</title>
+    <sect2>
+      <title id="Using-mt">Using mt(1) to control the tape drive</title>
 
       <indexterm>
 	<primary>tape media</primary>
-	<secondary>Exabyte (8mm) tapes</secondary>
+	<secondary>mt</secondary>
       </indexterm>
 
-      <para>8mm tapes are the most common SCSI tape drives; they are
-	the best choice of exchanging tapes.  Nearly every site has an
-	Exabyte 2&nbsp;GB 8mm tape drive.  8mm drives are reliable,
-	convenient and quiet.  Cartridges are inexpensive and small
-	(4.8 x 3.3 x 0.6 inches; 122 x 84 x 15 mm).  One downside of
-	8mm tape is relatively short head and tape life due to the
-	high rate of relative motion of the tape across the
-	heads.</para>
-
-      <para>Data throughput ranges from ~250&nbsp;kB/s to
-	~500&nbsp;kB/s.  Data sizes start at 300&nbsp;MB and go up to
-	7&nbsp;GB.  Hardware compression, available with most of these
-	drives, approximately doubles the capacity.  These drives are
-	available as single units or multi-drive tape libraries with 6
-	drives and 120 tapes in a single cabinet.  Tapes are changed
-	automatically by the unit.  Library capacities reach
-	840+&nbsp;GB.</para>
-
-      <para>The Exabyte <quote>Mammoth</quote> model supports
-	12&nbsp;GB on one tape (24&nbsp;GB with compression) and costs
-	approximately twice as much as conventional tape
-	drives.</para>
-
-      <para>Data is recorded onto the tape using helical-scan, the
-	heads are positioned at an angle to the media (approximately 6
-	degrees).  The tape wraps around 270 degrees of the spool that
-	holds the heads.  The spool spins while the tape slides over
-	the spool.  The result is a high density of data and closely
-	packed tracks that angle across the tape from one edge to the
-	other.</para>
+      <para>mt(1) is the FreeBSD utility for controlling other operations
+        of the tape drive such as seeking through files on a tape or writing
+        tape control marks to the tape.
+	</para>
+      <para>For example you have already written several backups to the tape
+        and you wish to save the first 3 backups without overwriting them.
+  	<screen>mt -f <devicename>/dev/nsa0</devicename> fsf 3</screen>
+      </para>
     </sect2>
 
-    <sect2 id="backups-tapebackups-qic">
-      <title>QIC</title>
+    <sect2>
+      <title id="Using-tar-on-tape">Using tar(1) to read/write backups on tape</title>
 
-      <indexterm>
-	<primary>tape media</primary>
-	<secondary>QIC-150</secondary>
-      </indexterm>
-
-      <para>QIC-150 tapes and drives are, perhaps, the most common
-	tape drive and media around.  QIC tape drives are the least
-	expensive <quote>serious</quote> backup drives.  The downside
-	is the cost of media.  QIC tapes are expensive compared to 8mm
-	or 4mm tapes, up to 5 times the price per GB data storage.
-	But, if your needs can be satisfied with a half-dozen tapes,
-	QIC may be the correct choice.  QIC is the
-	<emphasis>most</emphasis> common tape drive.  Every site has a
-	QIC drive of some density or another.  Therein lies the rub,
-	QIC has a large number of densities on physically similar
-	(sometimes identical) tapes.  QIC drives are not quiet.  These
-	drives audibly seek before they begin to record data and are
-	clearly audible whenever reading, writing or seeking.  QIC
-	tapes measure 6&nbsp;x 4&nbsp;x 0.7 inches (152&nbsp;x
-	102&nbsp;x 17 mm).</para>
-
-      <para>Data throughput ranges from ~150&nbsp;kB/s to
-	~500&nbsp;kB/s.  Data capacity ranges from 40&nbsp;MB to
-	15&nbsp;GB.  Hardware compression is available on many of the
-	newer QIC drives.  QIC drives are less frequently installed;
-	they are being supplanted by DAT drives.</para>
-
-      <para>Data is recorded onto the tape in tracks.  The tracks run
-	along the long axis of the tape media from one end to the
-	other.  The number of tracks, and therefore the width of a
-	track, varies with the tape's capacity.  Most if not all newer
-	drives provide backward-compatibility at least for reading
-	(but often also for writing).  QIC has a good reputation
-	regarding the safety of the data (the mechanics are simpler
-	and more robust than for helical scan drives).</para>
-
-      <para>Tapes should be retired from use after 5,000
-	backups.</para>
+      <para>An example of a simple backup using tar(1) and a tape drive.
+        <screen>tar cv <filename>file</filename></screen>
+        As the default tape drive is <devicename>/dev/sa0</devicename>
+        there is no need to specify it.
+        To specify a specific tape deivce from the command line.
+        <screen>tar cvf <devicename>/dev/sa1</devicename><filename>dir</filename></screen>
+      </para>
+      <para>Typical use to recover files backed up with tar from a tape.
+        <screen>tar xvf <devicename>/dev/sa0</devicename></screen>
+      </para>
     </sect2>
-
-    <sect2 id="backups-tapebackups-dlt">
-      <title>DLT</title>
-
-      <indexterm>
-	<primary>tape media</primary>
-	<secondary>DLT</secondary>
-      </indexterm>
-
-      <para>DLT has the fastest data transfer rate of all the drive
-	types listed here.  The 1/2" (12.5mm) tape is contained in a
-	single spool cartridge (4 x 4 x 1 inches; 100 x 100 x 25 mm).
-	The cartridge has a swinging gate along one entire side of the
-	cartridge.  The drive mechanism opens this gate to extract the
-	tape leader.  The tape leader has an oval hole in it which the
-	drive uses to <quote>hook</quote> the tape.  The take-up spool
-	is located inside the tape drive.  All the other tape
-	cartridges listed here (9 track tapes are the only exception)
-	have both the supply and take-up spools located inside the
-	tape cartridge itself.</para>
-
-      <para>Data throughput is approximately 1.5&nbsp;MB/s, three
-	times the throughput of 4mm, 8mm, or QIC tape drives.  Data
-	capacities range from 10&nbsp;GB to 20&nbsp;GB for a single
-	drive.  Drives are available in both multi-tape changers and
-	multi-tape, multi-drive tape libraries containing from 5 to
-	900 tapes over 1 to 20 drives, providing from 50&nbsp;GB to
-	9&nbsp;TB of storage.</para>
-
-      <para>With compression, DLT Type IV format supports up to
-	70&nbsp;GB capacity.</para>
-
-      <para>Data is recorded onto the tape in tracks parallel to the
-	direction of travel (just like QIC tapes).  Two tracks are
-	written at once.  Read/write head lifetimes are relatively
-	long; once the tape stops moving, there is no relative motion
-	between the heads and the tape.</para>
-    </sect2>
-
+    
     <sect2>
-      <title id="backups-tapebackups-ait">AIT</title>
+      <title id="Using-dump-on-tape">Using restore(8)/dump(8) to read/write backups on tape</title>
 
-      <indexterm>
-	<primary>tape media</primary>
-	<secondary>AIT</secondary>
-      </indexterm>
-
-      <para>AIT is a new format from Sony, and can hold up to
-	50&nbsp;GB (with compression) per tape.  The tapes contain
-	memory chips which retain an index of the tape's contents.
-	This index can be rapidly read by the tape drive to determine
-	the position of files on the tape, instead of the several
-	minutes that would be required for other tapes.  Software such
-	as <application>SAMS:Alexandria</application> can operate
-	forty or more AIT tape libraries, communicating directly with
-	the tape's memory chip to display the contents on screen,
-	determine what files were backed up to which tape, locate the
-	correct tape, load it, and restore the data from the
-	tape.</para>
-
-      <para>Libraries like this cost in the region of $20,000, pricing
-	them a little out of the hobbyist market.</para>
+      <para>An example of a simple backup using dump(8) and a tape drive.
+        <screen>dump -0u -f <devicename>/dev/nsa0</devicename> <filename>/usr</filename></screen>
+      </para>
+      <para>Typical use to recover files backed up with dump(8) from a tape.
+        <screen>restore -f <devicename>/dev/nsa0</devicename></screen>
+      </para>
     </sect2>
 
-    <sect2>
-      <title>Using a New Tape for the First Time</title>
-
-      <para>The first time that you try to read or write a new,
-	completely blank tape, the operation will fail.  The console
-	messages should be similar to:</para>
-
-      <screen>sa0(ncr1:4:0): NOT READY asc:4,1
-sa0(ncr1:4:0):  Logical unit is in process of becoming ready</screen>
-
-      <para>The tape does not contain an Identifier Block (block
-	number 0).  All QIC tape drives since the adoption of QIC-525
-	standard write an Identifier Block to the tape.  There are two
-	solutions:</para>
-
-      <itemizedlist>
-	<listitem>
-	  <para><command>mt fsf 1</command> causes the tape drive to
-	    write an Identifier Block to the tape.</para>
-	</listitem>
-
-	<listitem>
-	  <para>Use the front panel button to eject the tape.</para>
-
-	  <para>Re-insert the tape and <command>dump</command> data to
-	    the tape.</para>
-
-	  <para><command>dump</command> will report
-	    <errorname>DUMP: End of tape detected</errorname> and the
-	    console will show: <errorname>HARDWARE FAILURE info:280
-	      asc:80,96</errorname>.</para>
-
-	  <para>rewind the tape using:
-	    <command>mt rewind</command>.</para>
-
-	  <para>Subsequent tape operations are successful.</para>
-	</listitem>
-      </itemizedlist>
-    </sect2>
   </sect1>
 
   <sect1 id="backups-floppybackups">
>Release-Note:
>Audit-Trail:
>Unformatted:



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