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<TITLE>HOWTO-template for big HOWTOs : Structure</TITLE>
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<H2><A NAME="s2">2. Structure</A></H2>
<P><EM>A quick overview on how all parts fit together in the structure.
Here I use an example from my Multi Disk HOWTO.</EM>
<P>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.
<H2><A NAME="ss2.1">2.1 Logical structure</A>
(your index root)!structure, I/O subsystem
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.
|__ 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) __|
<P>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.
<H2><A NAME="ss2.2">2.2 Document structure</A>
<P>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.
<P>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.
<H2><A NAME="ss2.3">2.3 Reading plan</A>
<P><EM>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 example follows from my
<P>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
<DT><B>Expert</B><DD><P>(aka the elite). If you are familiar with Linux as well
as disk drive technologies you will find most of what you need in the
appendices. Additionally you are recommended to read the FAQ and the
<A HREF="big-howto-template-ld-12.html#bits-n-pieces">Bits'n'pieces</A>
<DT><B>Experienced</B><DD><P>(aka Competent). If you are familiar with computers
in general you can go straight to the chapters on
<A HREF="big-howto-template-ld-3.html#technologies">technologies</A>
and continue from there on.
<DT><B>Newbie</B><DD><P>(mostly harmless). You just have to read the whole thing.
Sorry. In addition you are also recommended to read all the other disk
related HOWTOs.
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