107 lines
4.4 KiB
HTML
107 lines
4.4 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<HTML>
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<HEAD>
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<META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
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<TITLE>HOWTO: Multi Disk System Tuning: Structure</TITLE>
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<LINK HREF="Multi-Disk-HOWTO-3.html" REL=next>
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<LINK HREF="Multi-Disk-HOWTO-1.html" REL=previous>
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<LINK HREF="Multi-Disk-HOWTO.html#toc2" REL=contents>
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</HEAD>
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<BODY>
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<A HREF="Multi-Disk-HOWTO-3.html">Next</A>
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<A HREF="Multi-Disk-HOWTO-1.html">Previous</A>
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<A HREF="Multi-Disk-HOWTO.html#toc2">Contents</A>
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<HR>
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<H2><A NAME="s2">2. Structure</A></H2>
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<P>As this type of document is supposed to be as much for learning
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as a technical reference document I have rearranged the structure
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to this end. For the designer of a system it is more useful to
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have the information presented in terms of the goals of this exercise
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than from the point of view of the logical layer structure of the
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devices themselves. Nevertheless this document would not be complete
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without such a layer structure the computer field is so full of, so
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I will include it here as an introduction to how it works.
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<P>It is a long time since the <EM>mini</EM> in mini-HOWTO could be defended
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as proper but I am convinced that this document is as long as it needs
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to be in order to make the right design decisions, and not longer.
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<P>
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<H2><A NAME="ss2.1">2.1 Logical structure</A>
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</H2>
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<P>
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<!--
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disk!structure, I/O subsystem
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-->
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This is based on how each layer access each other, traditionally
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with the application on top and the physical layer on the bottom.
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It is quite useful to show the interrelationship between each of
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the layers used in controlling drives.
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<BLOCKQUOTE><CODE>
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<PRE>
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___________________________________________________________
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|__ File structure ( /usr /tmp etc) __|
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|__ File system (ext2fs, vfat etc) __|
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|__ Volume management (AFS) __|
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|__ RAID, concatenation (md) __|
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|__ Device driver (SCSI, IDE etc) __|
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|__ Controller (chip, card) __|
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|__ Connection (cable, network) __|
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|__ Drive (magnetic, optical etc) __|
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-----------------------------------------------------------
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</PRE>
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</CODE></BLOCKQUOTE>
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<P>In the above diagram both volume management and RAID and concatenation
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are optional layers. The 3 lower layers are in hardware.
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All parts are discussed at length later on in this document.
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<P>
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<H2><A NAME="ss2.2">2.2 Document structure</A>
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</H2>
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<P>Most users start out with a given set of hardware and some plans on
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what they wish to achieve and how big the system should be. This is
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the point of view I will adopt in this document in presenting the
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material, starting out with hardware, continuing with design constraints
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before detailing the design strategy that I have found to work well.
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I have used this both for my own personal computer at home, a multi
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purpose server at work and found it worked quite well. In addition my
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Japanese co-worker in this project have applied the same strategy on
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a server in an academic setting with similar success.
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<P>Finally at the end I have detailed some configuration tables for use
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in your own design. If you have any comments regarding this or notes
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from your own design work I would like to hear from you so this
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document can be upgraded.
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<P>
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<H2><A NAME="ss2.3">2.3 Reading plan</A>
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</H2>
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<P>Although not the biggest HOWTO it is nevertheless rather big already
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and I have been requested to make a reading plan to make it possible
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to cut down on the volume
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<P>
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<DL>
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<DT><B>Expert</B><DD><P>(aka the elite). If you are familiar with Linux as well
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as disk drive technologies you will find most of what you need in the
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appendices. Additionally you are recommended to read the FAQ and the
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<A HREF="Multi-Disk-HOWTO-20.html#bits-n-pieces">Bits'n'pieces</A>
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chapter.
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<P>
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<DT><B>Experienced</B><DD><P>(aka Competent). If you are familiar with computers
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in general you can go straight to the chapters on
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<A HREF="Multi-Disk-HOWTO-6.html#technologies">technologies</A>
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and continue from there on.
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<P>
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<DT><B>Newbie</B><DD><P>(mostly harmless). You just have to read the whole thing.
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Sorry. In addition you are also recommended to read all the other disk
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related HOWTOs.
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</DL>
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<P>
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<P>
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<HR>
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<A HREF="Multi-Disk-HOWTO-3.html">Next</A>
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<A HREF="Multi-Disk-HOWTO-1.html">Previous</A>
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<A HREF="Multi-Disk-HOWTO.html#toc2">Contents</A>
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</BODY>
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</HTML>
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