Date: Thu, 17 Apr 2003 20:10:16 -0700 (PDT) From: Jim Brown <jpb@sixshooter.v6.thrupoint.net> To: freebsd-doc@FreeBSD.org Subject: Re: docs/50664: Handbook 12.4.1 (CCD) needs work Message-ID: <200304180310.h3I3AG3T021030@freefall.freebsd.org>
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The following reply was made to PR docs/50664; it has been noted by GNATS.
From: Jim Brown <jpb@sixshooter.v6.thrupoint.net>
To: freebsd-gnats-submit@FreeBSD.org, murray@freebsd.org
Cc:
Subject: Re: docs/50664: Handbook 12.4.1 (CCD) needs work
Date: Thu, 17 Apr 2003 23:06:11 -0400
Hi,
Here is an update of Handbook 12.4.1 (CCD) per docs/50664.
Hope this helps,
jpb
===
Index: chapter.sgml
===================================================================
RCS file: /home/ncvs/doc/en_US.ISO8859-1/books/handbook/disks/chapter.sgml,v
retrieving revision 1.145
diff -u -r1.145 chapter.sgml
--- chapter.sgml 2003/03/26 02:11:55 1.145
+++ chapter.sgml 2003/04/17 21:50:46
@@ -342,57 +342,57 @@
<author>
<firstname>Christopher</firstname>
<surname>Shumway</surname>
- <contrib>Written by </contrib>
+ <contrib>Original work by </contrib>
</author>
</authorgroup>
<authorgroup>
<author>
<firstname>Valentino</firstname>
<surname>Vaschetto</surname>
- <contrib>Marked up by </contrib>
+ <contrib>Original markup by </contrib>
</author>
</authorgroup>
+ <authorgroup>
+ <author>
+ <firstname>Jim</firstname>
+ <surname>Brown</surname>
+ <contrib>Revised by </contrib>
+ </author>
+ </authorgroup>
</sect3info>
- <title>ccd (Concatenated Disk Configuration)</title>
+ <title>Concatenated Disk Driver (CCD) Configuration</title>
<para>When choosing a mass storage solution the most important
- factors to consider are speed, reliability, and cost. It is very
- rare to have all three in favor; normally a fast, reliable mass
+ factors to consider are speed, reliability, and cost. It is
+ rare to have all three in balance; normally a fast, reliable mass
storage device is expensive, and to cut back on cost either speed
- or reliability must be sacrificed. In designing my system, I
- ranked the requirements by most favorable to least favorable. In
- this situation, cost was the biggest factor. I needed a lot of
- storage for a reasonable price. The next factor, speed, is not
- quite as important, since most of the usage would be over a one
- hundred megabit switched Ethernet, and that would most likely be
- the bottleneck. The ability to spread the file input/output
- operations out over several disks would be more than enough speed
- for this network. Finally, the consideration of reliability was
- an easy one to answer. All of the data being put on this mass
- storage device was already backed up on CD-R's. This drive was
- primarily here for online live storage for easy access, so if a
- drive went bad, I could just replace it, rebuild the file system,
- and copy back the data from CD-R's.</para>
-
- <para>To sum it up, I need something that will give me the most
- amount of storage space for my money. The cost of large IDE disks
- are cheap these days. I found a place that was selling Western
- Digital 30.7GB 5400 RPM IDE disks for about one-hundred and thirty
- US dollars. I bought three of them, giving me approximately
- ninety gigabytes of online storage.</para>
+ or reliability must be sacrificed.</para>
+
+ <para>In designing the system described below, cost was chosen
+ as the most important factor, followed by speed, then reliability.
+ Data transfer speed for this system is ulitmately
+ constrained by the network. And while reliability is very
important,
+ the CCD drive described below serves online data that is already
+ fully backed up on CD-R's and can easily be replaced.</para>
+
+ <para>Defining your own requirements is the first step
+ in choosing a mass storage solution. If your requirements prefer
+ speed or reliability over cost, your solution will differ from
+ the system described in this section.</para>
+
<sect4 id="ccd-installhw">
<title>Installing the Hardware</title>
- <para>I installed the hard drives in a system that already
- had one IDE disk in as the system disk. The ideal solution
- would be for each IDE disk to have its own IDE controller
- and cable, but without fronting more costs to acquire a dual
- IDE controller this would not be a possibility. So, I
- jumpered two disks as slaves, and one as master. One went
- on the first IDE controller as a slave to the system disk,
- and the other two where slave/master on the secondary IDE
- controller.</para>
+ <para>In addition to the IDE system disk, three Western
+ Digital 30GB, 5400 RPM IDE disks form the core
+ of the CCD disk described below providing approximately
+ 90GB of online storage. Ideally,
+ each IDE disk would have its own IDE controller
+ and cable, but to minimize cost, additional
+ IDE controllers were not used. Instead the disks were
+ configured with jumpers so that each IDE controller has
+ one master, and one slave.</para>
<para>Upon reboot, the system BIOS was configured to
automatically detect the disks attached. More importantly,
@@ -403,74 +403,74 @@
ad2: 29333MB <WDC WD307AA> [59598/16/63] at ata1-master UDMA33
ad3: 29333MB <WDC WD307AA> [59598/16/63] at ata1-slave
UDMA33</programlisting>
- <para>At this point, if FreeBSD does not detect the disks, be
- sure that you have jumpered them correctly. I have heard
- numerous reports with problems using cable select instead of
- true slave/master configuration.</para>
-
- <para>The next consideration was how to attach them as part of
- the file system. I did a little research on &man.vinum.8;
- (<xref linkend="vinum-vinum">) and
- &man.ccd.4;. In this particular configuration, &man.ccd.4;
- appeared to be a better choice mainly because it has fewer
- parts. Less parts tends to indicate less chance of breakage.
- Vinum appears to be a bit of an overkill for my needs.</para>
+ <para>Note that if FreeBSD does not detect all the disks, ensure that
+ you have jumpered them correctly. Most IDE drives also have a
+ <quote>Cable Select</quote> jumper. This is
<emphasis>not</emphasis>
+ the jumper for the master/slave relationship. Consult the drive
+ documentation for help in identifying the correct jumper.</para>
+
+ <para>Next, consider how to attach them as part of
+ the file system. You should research both &man.vinum.8;
+ (<xref linkend="vinum-vinum">) and &man.ccd.4;. In this
+ particular configuration, &man.ccd.4; was chosen.</para>
</sect4>
<sect4 id="ccd-setup">
<title>Setting up the CCD</title>
- <para><application>CCD</application> allows me to take
+ <para><application>CCD</application> allows you to take
several identical disks and concatenate them into one
logical file system. In order to use
- <application>ccd</application>, I need a kernel with
- <application>ccd</application> support built into it. I
- added this line to my kernel configuration file and rebuilt
- the kernel:</para>
+ <application>ccd</application>, you need a kernel with
+ <application>ccd</application> support built in.
+ Add this line to your kernel configuration file, rebuild, and
+ reinstall the kernel:</para>
<programlisting>pseudo-device ccd 4</programlisting>
<note><para>In FreeBSD 5.0, it is not necessary to specify
a number of ccd devices, as the ccd device driver is now
- cloning -- new device instances will automatically be
+ self-cloning -- new device instances will automatically be
created on demand.</para></note>
<para><application>ccd</application> support can also be
- loaded as a kernel loadable module in FreeBSD 4.0 or
- later.</para>
+ loaded as a kernel loadable module in FreeBSD 3.0 or
+ later. See &man.ccd.4; for information on loading
+ <application>ccd</application> as a kernel loadable
module.</para>
- <para>To set up <application>ccd</application>, first I need
- to disklabel the disks. Here is how I disklabeled
- them:</para>
+ <para>To set up <application>ccd</application>, you must first use
+ &man.disklabel.8 to label the disks:</para>
<programlisting>disklabel -r -w ad1 auto
disklabel -r -w ad2 auto
disklabel -r -w ad3 auto</programlisting>
- <para>This created a disklabel ad1c, ad2c and ad3c that
+ <para>This creates a disklabel for ad1c, ad2c and ad3c that
spans the entire disk.</para>
- <para>The next step is to change the disklabel type. To do
- that I had to edit the disklabel:</para>
+ <para>The next step is to change the disklabel type.
+ You can use <application>disklabel</application> to
+ edit the disks:</para>
<programlisting>disklabel -e ad1
disklabel -e ad2
disklabel -e ad3</programlisting>
- <para>This opened up the current disklabel on each disk
- respectively in whatever editor the <envar>EDITOR</envar>
- environment variable was set to, in my case, &man.vi.1;.
- Inside the editor I had a section like this:</para>
+ <para>This openes up the current disklabel on each disk
+ with the editor specified by the <envar>EDITOR</envar>
+ environment variable, typically &man.vi.1;.</para>
+ <para>An unmodified disklabel will look something like this:</para>
+
<programlisting>8 partitions:
# size offset fstype [fsize bsize bps/cpg]
c: 60074784 0 unused 0 0 0 # (Cyl. 0 -
59597)</programlisting>
- <para>I needed to add a new "e" partition for &man.ccd.4; to
- use. This usually can be copied of the "c" partition, but
- the <option>fstype</option> must be <userinput>4.2BSD</userinput>.
- Once I was done,
- my disklabel should look like this:</para>
+ <para>Add a new "e" partition for &man.ccd.4; to
+ use. This can usually be copied from the <quote>c</quote> partition, but
+ the <option>fstype</option> <emphasis>must</emphasis>
+ be <userinput>4.2BSD</userinput>. The disklabel should now look
+ something like this:</para>
<programlisting>8 partitions:
# size offset fstype [fsize bsize bps/cpg]
@@ -482,12 +482,7 @@
<sect4 id="ccd-buildingfs">
<title>Building the File System</title>
- <para>Now that I have all of the disks labeled, I needed to
- build the <application>ccd</application>. To do that, I
- used a utility called &man.ccdconfig.8;.
- <command>ccdconfig</command> takes several arguments, the
- first argument being the device to configure, in this case,
- <devicename>/dev/ccd0c</devicename>. The device node for
+ <para>The device node for
<devicename>ccd0c</devicename> may not exist yet, so to
create it, perform the following commands:</para>
@@ -496,60 +491,89 @@
<note><para>In FreeBSD 5.0, &man.devfs.5; will automatically
manage device nodes in <filename>/dev</filename>, so use of
- <command>MAKEDEV</command> is not necessary.</para></note>
-
- <para>The next argument <command>ccdconfig</command> expects
- is the interleave for the file system. The interleave
- defines the size of a stripe in disk blocks, normally five
- hundred and twelve bytes. So, an interleave of thirty-two
- would be sixteen thousand three hundred and eighty-four
- bytes.</para>
-
- <para>After the interleave comes the flags for
- <command>ccdconfig</command>. If you want to enable drive
- mirroring, you can specify a flag here. In this
- configuration, I am not mirroring the
- <application>ccd</application>, so I left it as zero.</para>
-
- <para>The final arguments to <command>ccdconfig</command>
- are the devices to place into the array. Putting it all
- together I get this command:</para>
-
- <programlisting>ccdconfig ccd0 32 0 /dev/ad1e /dev/ad2e
/dev/ad3e</programlisting>
+ <command>MAKEDEV</command> may not be necessary.</para></note>
- <para>This configures the <application>ccd</application>.
- I can now &man.newfs.8; the file system.</para>
+ <para>Now that you have all of the disks labeled, you must
+ build the <application>ccd</application>. To do that,
+ use &man.ccdconfig.8;, with options similar to the following:
+
+ <programlisting>ccdconfig ccd0 32 0 /dev/ad1e /dev/ad2e
/dev/ad3e</programlisting>
+
+ The use and meaning of each option is shown below:</para>
+
+ <programlisting>ccd0 <co id="co-ccd-dev">
+32 <co id="co-ccd-interleave">
+0 <co id="co-ccd-flags">
+/dev/ad1e <co id="co-ccd-devs">
+/dev/ad2e
+/dev/ad3e</programlisting>
+
+ <calloutlist>
+
+ <callout arearefs="co-ccd-dev">
+ <para>The first argument is the device to configure, in this case,
+ <devicename>/dev/ccd0c</devicename>. The <filename>/dev/</filename>
+ portion is optional.</para>
+ </callout>
+
+ <callout arearefs="co-ccd-interleave">
+
+ <para>The interleave for the file system. The interleave
+ defines the size of a stripe in disk blocks, each normally 512 bytes.
+ So, an interleave of 32 would be 16,384 bytes.</para>
+ </callout>
+
+ <callout arearefs="co-ccd-flags">
+ <para>Flags for <command>ccdconfig</command>. If you want to enable
drive
+ mirroring, you can specify a flag here. This
+ configuration does not provide mirroring for
+ <application>ccd</application>, so it is set at 0 (zero).</para>
+ </callout>
+
+ <callout arearefs="co-ccd-devs">
+ <para>The final arguments to <command>ccdconfig</command>
+ are the devices to place into the array. Use the complete pathname
+ for each device.</para>
+ </callout>
+ </calloutlist>
+
+
+ <para>After running <command>ccdconfig</command> the
<application>ccd</application>
+ is configured. A file system can be installed. Refer to
&man.newfs.8;
+ for options, or simply run: </para>
<programlisting>newfs /dev/ccd0c</programlisting>
+
</sect4>
<sect4 id="ccd-auto">
<title>Making it all Automatic</title>
- <para>Finally, if I want to be able to mount the
- <application>ccd</application>, I need to
- configure it first. I write out my current configuration to
+ <para>Generally, you will want to mount the
+ <application>ccd</application> upon each reboot. To do this, you must
+ configure it first. Write out your current configuration to
<filename>/etc/ccd.conf</filename> using the following command:</para>
<programlisting>ccdconfig -g > /etc/ccd.conf</programlisting>
- <para>When I reboot, the script <command>/etc/rc</command>
- runs <command>ccdconfig -C</command> if /etc/ccd.conf
+ <para>During reboot, the script <command>/etc/rc</command>
+ runs <command>ccdconfig -C</command> if
<filename>/etc/ccd.conf</filename>
exists. This automatically configures the
<application>ccd</application> so it can be mounted.</para>
- <para>If you are booting into single user mode, before you can
+ <note><para>If you are booting into single user mode, before you can
<command>mount</command> the <application>ccd</application>, you
need to issue the following command to configure the
array:</para>
<programlisting>ccdconfig -C</programlisting>
+ </note>
- <para>Then, we need an entry for the
- <application>ccd</application> in
+ <para>To automatically mount the <application>ccd</application>,
+ place an entry for the <application>ccd</application> in
<filename>/etc/fstab</filename> so it will be mounted at
- boot time.</para>
+ boot time:</para>
<programlisting>/dev/ccd0c /media ufs rw 2
2</programlisting>
</sect4>
@@ -566,7 +590,7 @@
storage. &man.vinum.8; implements the RAID-0, RAID-1 and
RAID-5 models, both individually and in combination.</para>
- <para>See the <xref linkend="vinum-vinum"> for more
+ <para>See <xref linkend="vinum-vinum"> for more
information about &man.vinum.8;.</para>
</sect3>
</sect2>
@@ -578,16 +602,19 @@
<primary>RAID</primary>
<secondary>Hardware</secondary>
</indexterm>
+
<para>FreeBSD also supports a variety of hardware
<acronym>RAID</acronym>
- controllers. In which case the actual <acronym>RAID</acronym> system
- is built and controlled by the card itself. Using an on-card
- <acronym>BIOS</acronym>, the card will control most of the disk operations
- itself. The following is a brief setup using a Promise <acronym>IDE
RAID</acronym>
- controller. When this card is installed and the system started up, it will
- display a prompt requesting information. Follow the on screen instructions
- to enter the cards setup screen. From here a user should have the ability
to
- combine all the attached drives. When doing this, the disk(s) will look
like
- a single drive to FreeBSD. Other <acronym>RAID</acronym> levels can be
setup
+ controllers. These devices control a <acronym>RAID</acronym>
subsystem
+ without the need for FreeBSD specific <acronym>RAID</acronym>
software
+ that manages the <acronym>RAID</acronym> array.</para>
+
+ <para>Using an on-card <acronym>BIOS</acronym>, the card controls most
of the disk operations
+ itself. The following is a brief setup description using a <acronym>Promise
IDE RAID</acronym>
+ controller. When this card is installed and the system is started up, it
+ displays a prompt requesting information. Follow the instructions
+ to enter the cards setup screen. From here, you have the ability to
+ combine all the attached drives. After doing so, the disk(s) will look like
+ a single drive to FreeBSD. Other <acronym>RAID</acronym> levels can be set
up
accordingly.
</para>
</sect2>
@@ -608,7 +635,7 @@
ad6: hard error reading fsbn 1116119 of 0-7 (ad6 bn 1116119; cn 1107 tn 4 sn
11) status=59 error=40
ar0: WARNING - mirror lost</programlisting>
- <para>Using &man.atacontrol.8;, check to see how things look:</para>
+ <para>Using &man.atacontrol.8;, check for further information:</para>
<screen>&prompt.root; <userinput>atacontrol list</userinput>
ATA channel 0:
@@ -656,8 +683,9 @@
</step>
<step>
- <para>The rebuild command hangs until complete, its possible to open
another
- terminal and check on the progress by issuing the following
command:</para>
+ <para>The rebuild command hangs until complete. However, it is possible
to open another
+ terminal (using <keycombo action="simul"><keycap>Alt</keycap>
<keycap>F<replaceable>n</replaceable></keycap></keycombo>)
+ and check on the progress by issuing the following command:</para>
<screen>&prompt.root; <userinput>dmesg | tail -10</userinput>
[output removed]
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