-<!-- Section1: structure -->
-
- <sect1 id="structure">
- <title>Structure</title>
-
- <para>
- <emphasis>A quick overview on how all parts fit together in the overall
- structure. An example from the Multi Disk HOWTO is used.</emphasis>
- </para>
-
- <para>
- As this type of document is supposed to be as much for learning as
- a technical reference document I have rearranged the structure to
- this end. For the designer of a system it is more useful to have
- the information presented in terms of the goals of this exercise
- than from the point of view of the logical layer structure of the
- devices themselves. Nevertheless this document would not be
- complete without such a layer structure the computer field is so
- full of, so I will include it here as an introduction to how it
- works.
- </para>
-
-<!-- Section2: logical-struct -->
-
- <sect2 id="logical-struct">
- <title>Logical structure</title>
-
- <indexterm>
- <primary>disk!structure, I/O subsystem</primary>
- </indexterm>
-
- <para>
- This is based on how each layer access each other, traditionally
- with the application on top and the physical layer on the bottom.
- It is quite useful to show the interrelationship between each of
- the layers used in controlling drives.
-
- <screen>
- ___________________________________________________________
- |__ File structure ( /usr /tmp etc) __|
- |__ File system (ext2fs, vfat etc) __|
- |__ Volume management (AFS) __|
- |__ RAID, concatenation (md) __|
- |__ Device driver (SCSI, IDE etc) __|
- |__ Controller (chip, card) __|
- |__ Connection (cable, network) __|
- |__ Drive (magnetic, optical etc) __|
- -----------------------------------------------------------
- </screen>
- </para>
-
- <para>
- In the above diagram both volume management and RAID and
- concatenation are optional layers. The 3 lower layers are in
- hardware. All parts are discussed at length later on in this
- document.
- </para>
- </sect2>
-
-<!-- Section2: doc-struct -->
-
- <sect2 id="doc-struct">
- <title>Document structure</title>
-
- <para>
- Most users start out with a given set of hardware and some plans
- on what they wish to achieve and how big the system should be.
- This is the point of view I will adopt in this document in
- presenting the material, starting out with hardware, continuing
- with design constraints before detailing the design strategy that
- I have found to work well. I have used this both for my own
- personal computer at home, a multi purpose server at work and
- found it worked quite well. In addition my Japanese co-worker in
- this project have applied the same strategy on a server in an
- academic setting with similar success.
- </para>
-
- <para>
- Finally at the end I have detailed some configuration tables for
- use in your own design. If you have any comments regarding this
- or notes from your own design work I would like to hear from you
- so this document can be upgraded.
- </para>
- </sect2>
-
-<!-- Section2: reading-plan -->
-
- <sect2 id="reading-plan">
- <title>Reading plan</title>
-
- <para>
- <emphasis>As you go beyond 50 pages or so there will be a lot of
- text that experts and even the experienced do not need to read.
- Keeping in mind that we wish to care for all kinds of people in
- the Linux world we might have to make a reading plan. Again,
- an example follows from the Multi Disk HOWTO.</emphasis>
- </para>
-
- <para>
- Although not the biggest HOWTO it is nevertheless rather big
- already and I have been requested to make a reading plan to make
- it possible to cut down on the volume.
- </para>
-
- <para>
- <variablelist>
-
- <varlistentry>
- <term>Expert</term>