Stein Gjoen

sgjoen@nyx.net

v0.02 , 28 May 2000 template This is a fully working template for big HOWTOs. The source contains fully described slots to make a convenient framework for you to fill in for making your own HOWTO, suggesting some names, conventions and contents for the chapters.

disk!introduction For various reasons this brand new release is codenamed the release release. New code names will appear as per industry standard guidelines to emphasize the state-of-the-art-ness of this document. This document was written when I read a feedback asking for a template to fill in to make new HOWTOs. This template is made by extracting the skeletal structure of the Multi Disk HOWTO which is a rather large HOWTO. Stating the background is a simple way to getting started writing the intro. First of all we need a bit of legalese. Recent development shows it is quite important.

This HOWTO is copyrighted 2000 Stein Gjoen. Replace with your name when you use this skeleton for a new HOWTO. Unless otherwise stated, Linux HOWTO documents are copyrighted by their respective authors. Linux HOWTO documents may be reproduced and distributed in whole or in part, in any medium physical or electronic, as long as this copyright notice is retained on all copies. Commercial redistribution is allowed and encouraged; however, the author would like to be notified of any such distributions. All translations, derivative works, or aggregate works incorporating any Linux HOWTO documents must be covered under this copyright notice. That is, you may not produce a derivative work from a HOWTO and impose additional restrictions on its distribution. Exceptions to these rules may be granted under certain conditions; please contact the Linux HOWTO coordinator at the address given below. In short, we wish to promote dissemination of this information through as many channels as possible. However, we do wish to retain copyright on the HOWTO documents, and would like to be notified of any plans to redistribute the HOWTOs. If you have questions, please contact at linux-howto@metalab.unc.edu via email.

Use the information in this document at your own risk. I disavow any potential liability for the contents of this document. Use of the concepts, examples, and/or other content of this document is entirely at your own risk. All copyrights are owned by their owners, unless specifically noted otherwise. Use of a term in this document should not be regarded as affecting the validity of any trademark or service mark. Naming of particular products or brands should not be seen as endorsements. You are strongly recommended to take a backup of your system before major installation and backups at regular intervals.

(your index root)!news on This is where you make a summary of what it news. When a HOWTO exceeds 20 pages it takes more than a casual read to find the updates. This is where you help your readers with that, alerting them to specific and important news. This is the first release. No news yet. Tell people where the document home page is so the very newest release could be found in case of problems with the main Linux Documentation Project homepage. The following is a sample from my own HOWTO: The latest version number of this document can be gleaned from my plan entry if you finger my Nyx account. If you have the capacity it would be nice to make the HOWTO available in a number of formats Also, the latest version will be available on my web space on Nyx in a number of formats: HTML. plain ASCII text. compressed postscript US letter format. compressed postscript European A4 format. SGML source. Note that paper sizes vary in the world, A4 and US letter differ significantly.

It is always nice to acknowledge people who help you with inputs, it is also regarded by mane as important in the Linux world new economy. In this version I have the pleasure of acknowledging:

name (at) site.org

Scramble the addresses so email harversters cannot get addresses from your HOWTO and then spam people. That has happened in the past.

Not everyone speaks English, pointers to translations are nice. Also your translators tend to give very important inputs. German Translation by

someone (at) somewhere.de

Swedish Translation by

someone (at) somewhere.se

French Translation by

someone (at) somewhere.fr

Chinese Translation by

someone (at) somewhere.cn

Italian Translation by

someone (at) somewhere.it

Also Somecompany is acknowledged for sending me documentation on their gizmos as well as permission to quote from the material. These quotes have been approved before appearing here and will be clearly labelled. Any comments or suggestions can be mailed to my mail address on Nyx:

sgjoen@nyx.net

.

This section gives some simple SGML examples you could copy. Read the source to see how it was done.

Lists appears many times, in a number of formats: Unlisted bullets: Apples Oranges Bananas Tagged lists Fruits such as apples, oranges, and more. Nuts Don't eat too many; you are what you eat. Vegetables Potatos are spelled with care.

Links can be used within your documents to refer to diffent sections and chapters or to refer to documents external to yours. Internal links Click on link to jump to the top of this chapter. Note the anchor at the section tag. External links Click onthis link to jump to the LDP site. Note you can use http, ftp, news and other protocols in the locator if required. Note that the character ~ has to be escaped, see the source for details.

Avoid diagrams if possible as this cannot be rendered in the ascii outputs which are still needed by many around the world.

A quick overview on how all parts fit together in the structure. Here I use an example from my Multi Disk HOWTO. 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.

disk!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) __| ----------------------------------------------------------- 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.

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. 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.

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 HOWTO. 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. Expert (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 chapter. Experienced (aka Competent). If you are familiar with computers in general you can go straight to the chapters on and continue from there on. Newbie (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.

(your index root)!technologies Introduction of technology for the newbie with a few references to detailled works. Remember that not everyone has Internet access so you have to explain in sufficient details so even the newbie can get by.

(your index root)!implementation Now your readers should have a sufficient knowledge of what this is about and now we come to the hands on of implementing your clever scheme.

(your index root)!maintenance Few systems and designs are maintenence free, here you explain how to keep the system running.

(your index root)!advanced topics You can get most things up and running in a quick and dirty fashion, useful for testing and getting used to how things work. For more serious use you would need to be a little more advanced. This is the place to explain it all, if applicable.

(your index root)!information resources A HOWTO cannot describe everything, some times the user has to venture out on th enet to get more information or just updates. Here is the place to tell where and how. Again examples from my HOWTO, replace as needed. There is wealth of information one should go through when setting up a major system, for instance for a news or general Internet service provider. The FAQs in the following groups are useful:

disk!information resources!news groups Some of the most interesting news groups are: Storage. PC storage. AFS. SCSI. Linux setup. Most newsgroups have their own FAQ that are designed to answer most of your questions, as the name Frequently Asked Questions indicate. Fresh versions should be posted regularly to the relevant newsgroups. If you cannot find it in your news spool you could go directly to the FAQ main archive FTP site. The WWW versions can be browsed at FAQ main archive WWW site. Some FAQs have their own home site, of particular interest here are SCSI FAQ and comp.arch.storage FAQ.

disk!information resources!mailing lists These are low noise channels mainly for developers. Think twice before asking questions there as noise delays the development. Some relevant lists are linux-raid, linux-scsi and linux-ext2fs. Many of the most useful mailing lists run on the vger.rutgers.edu server but this is notoriously overloaded, so try to find a mirror. There are some lists mirrored at The Redhat Home Page. Many lists are also accessible at linuxhq, and the rest of the web site is a gold mine of useful information. If you want to find out more about the lists available you can send a message with the line lists to the list server at vger.rutgers.edu ( majordomo@vger.rutgers.edu). If you need help on how to use the mail server just send the line help to the same address. Due to the popularity of this server it is likely it takes a bit to time before you get a reply or even get messages after you send a subscribe command. There is also a number of other majordomo list servers that can be of interest such as the EATA driver list (linux-eata@mail.uni-mainz.de) and the Intelligent IO list linux-i2o@dpt.com. Mailing lists are in a state of flux but you can find links to a number of interesting lists from the Linux Documentation Homepage.

disk!information resources!HOWTOs These are intended as the primary starting points to get the background information as well as show you how to solve a specific problem. Some relevant HOWTOs are Bootdisk, Installation, SCSI and UMSDOS. The main site for these is the LDP archiveat Metalab (formerly known as Sunsite). There is a a new HOWTO out that deals with setting up a DPT RAID system, check out the DPT RAID HOWTO homepage.

disk!information resources!mini-HOWTOs These are the smaller free text relatives to the HOWTOs. Some relevant mini-HOWTOs are Backup-With-MSDOS, Diskless, LILO, Large Disk, Linux+DOS+Win95+OS2, Linux+OS2+DOS, Linux+Win95, NFS-Root, Win95+Win+Linux, ZIP Drive . You can find these at the same place as the HOWTOs, usually in a sub directory called mini. Note that these are scheduled to be converted into SGML and become proper HOWTOs in the near future. The old Linux Large IDE mini-HOWTO is no longer valid, instead read /usr/src/linux/drivers/block/README.ide or /usr/src/linux/Documentation/ide.txt.

disk!information resources!local In most distributions of Linux there is a document directory installed, have a look in the /usr/doc directory. where most packages store their main documentation and README files etc. Also you will here find the HOWTO archive ( /usr/doc/HOWTO) of ready formatted HOWTOs and also the mini-HOWTO archive ( /usr/doc/HOWTO/mini) of plain text documents. Many of the configuration files mentioned earlier can be found in the /etc directory. In particular you will want to work with the /etc/fstab file that sets up the mounting of partitions and possibly also /etc/mdtab file that is used for the md system to set up RAID. The kernel source in /usr/src/linux is, of course, the ultimate documentation. In other words, use the source, Luke. It should also be pointed out that the kernel comes not only with source code which is even commented (well, partially at least) but also an informative documentation directory. If you are about to ask any questions about the kernel you should read this first, it will save you and many others a lot of time and possibly embarrassment. Also have a look in your system log file ( /var/log/messages) to see what is going on and in particular how the booting went if too much scrolled off your screen. Using tail -f /var/log/messages in a separate window or screen will give you a continuous update of what is going on in your system. You can also take advantage of the /proc file system that is a window into the inner workings of your system. Use cat rather than more to view the files as they are reported as being zero length. Reports are that less works well here.

disk!information resources!WWW disk!information resources!web pages There is a huge number of informative web pages out there and by their very nature they change quickly so don't be too surprised if these links become quickly outdated. A good starting point is of course the Linux Documentation Project home page, an information central for documentation, project pages and much, much more. Please let me know if you have any other leads that can be of interest.

(your index root)!assistance, obtaining In the end you might find yourself unable to solve your problems and need help from someone else. The most efficient way is either to ask someone local or in your nearest Linux user group, search the web for the nearest one. Another possibility is to ask on Usenet News in one of the many, many newsgroups available. The problem is that these have such a high volume and noise (called low signal-to-noise ratio) that your question can easily fall through unanswered. No matter where you ask it is important to ask well or you will not be taken seriously. Saying just my disk does not work is not going to help you and instead the noise level is increased even further and if you are lucky someone will ask you to clarify. Instead describe your problems in some detail that will enable people to help you. The problem could lie somewhere you did not expect. Therefore you are advised to list up the following information on your system: Hardware Processor DMA IRQ Chip set (LX, BX etc) Bus (ISA, VESA, PCI etc) Expansion cards used (Disk controllers, video, IO etc) Software BIOS (On motherboard and possibly SCSI host adapters) LILO, if used Linux kernel version as well as possible modifications and patches Kernel parameters, if any Software that shows the error (with version number or date) Peripherals Type of disk drives with manufacturer name, version and type Other relevant peripherals connected to the same busses Remember that booting text is logged to /var/log/messages which can answer most of the questions above. Obviously if the drives fail you might not be able to get the log saved to disk but you can at least scroll back up the screen using the SHIFT and PAGE UP keys. It may also be useful to include part of this in your request for help but do not go overboard, keep it brief as a complete log file dumped to Usenet News is more than a little annoying.

(your index root)!conclusion Just summing up... Also a place for general recommendations.

(your index root)!FAQ (your index root)!frequently asked questions Check the newsgroups and try to determine some frequent problems and cover them here. Again an example from my HOWTO. This is just a collection of what I believe are the most common questions people might have. Give me more feedback and I will turn this section into a proper FAQ. Q:How many physical disk drives (spindles) does a Linux system need? A: Linux can run just fine on one drive (spindle). Having enough RAM (around 32 MB, and up to 64 MB) to support swapping is a better price/performance choice than getting a second disk. (E)IDE disk is usually cheaper (but a little slower) than SCSI. Q: Are there any disadvantages in this scheme? A: There is only a minor snag: if even a single partition overflows the system might stop working properly. The severity depends of course on what partition is affected. Still this is not hard to monitor, the command df gives you a good overview of the situation. Also check the swap partition(s) using free to make sure you are not about to run out of virtual memory. Q: OK, so should I split the system into as many partitions as possible for a single drive? A: No, there are several disadvantages to that. First of all maintenance becomes needlessly complex and you gain very little in this. In fact if your partitions are too big you will seek across larger areas than needed. This is a balance and dependent on the number of physical drives you have. (rest deleted.)

disk!miscellaneous This is basically a section where I stuff all the bits I have not yet decided where should go, yet that I feel is worth knowing about. It is a kind of transient area.

(your index root)!examples Example designs and sample configuration files and other relevant details is always handy