1、Chapter 2 Installation Preparation Certification Objectives 2.01 Planning the Installation 2.02 Intel CPU Hardware Selection and Configuration Packages to Be Installed. 1 Partitioning the Drive. 1 Hardware Compatibility. 4 RAM Sizing and Cache Issues. 5 Disk Subsystems (IDE, EIDE, and SCSI) 5 IRQ Se
2、ttings. 8 IRQs and Standard Serial Ports. 11 Serial and Other Interface Mice. 11 PC Card (PCMCIA) 12 One of the strong points of Red Hat Linux is its easy installation. There are several different methods of installation, and each of them is automated to a considerable degree. However, before the ac
3、tual installation, some preparation is necessary. CERTIFICATION OBJECTIVE 2.01 Planning the Installation Before any software can be installed, the computer has to be able to recognize the hardware it will be using. The installation process will ask you about your hardware, so have this data ready be
4、fore you start. You should know the make and model number for each of the following pieces of hardware, if you have them: SCSI controllers Network interface cards (NIC) Video cards Sound cards You might also need other information, such as the base I/O address and interrupt that each piece of hardwa
5、re uses. Later in this chapter, well discuss hardware compatibility for Linux. Packages to Be Installed Red Hat Linux comes conveniently bundled with an array of pre-configured software packages. Most likely, you will not need to install all of these packages, and for security reasons (or office pol
6、icy) it is a good idea not to. Your boss might not appreciate the office network being used to serve personal Web pages from each employees installation of an Apache Web server. Also, every computer on your network doesnt need to run the innd network news service. Limit the packages you install to o
7、nly the ones you need. If other packages are required later, they can be installed easily enough with the rpm tool. Partitioning the Drive It is recommended that you make several partitions when preparing your hard drive to install Linux. This is a good idea for various reasons. First, Red Hat Linux
8、 runs two filesystems: a Linux native filesystem, and a Linux swap space. Second, if you want to install Red Hat Linux and another operating system on the same computer, you will have to create separate partitions for each. The following section discusses more advantages of making partitions. Stabil
9、ity and Security The Linux native filesystem is usually divided among many hard drive partitions. The recommended configuration is a separate partition for each of these directories: /, /usr, /tmp, /var, and /home as well as separate partitions for corporate data, database services, and even the Web
10、 and FTP sites if they are expected to be large. Partitioning the hard drive in this manner keeps system, application, and user files isolated from each other. This aids in protecting the file space that the Linux kernel and the rest of your applications use. Files cannot grow across partitions. The
11、refore, an application that uses huge amounts of disk space, such as a newsgroup server, will not be able to use up all of the disk space needed by the Linux kernel. Another advantage is that if a bad spot develops on the hard drive, it will be easier to restore a single partition than the entire sy
12、stem. Stability is improved. Security, also, is improved. Multiple partitions give you the ability to mount some filesystems as read-only. For example, if there is no reason for any user (even root) to write to the /usr directory, mounting that partition as read-only will help protect those files fr
13、om being tampered with. While there are many incentives to partitioning your disk space, it might not be desirable for you. For single-user systems, or where disk space is scarce, a simpler filesystem layout would be called for. For example, if the /var directory is on its own partition of 300MB, on
14、ly 100MB might be used. That makes 200MB of wasted disk space. As of RH 7.x, both the web and ftp document roots have been added to /var. These may add additional disk space requirements for /var. Currently, there is no easy way to resize Linux partitions. Therefore, a lot of careful consideration s
15、hould be put into whether you want to partition your disk space, and how to do it. How Much Space Is Required? You should size your Linux partitions according to your needs and the function of the computer. For example, a mail server will require more space for the /var directory because the mail sp
16、ool resides in /var/spool/mail. You may even want to create a separate partition just to accommodate /var/spool/mail. As of RH 7.x, both the web and ftp document roots have been added to /var. These may add additional disk space requirements for /var. Generally, the root partition is a relatively mo
17、dest size, and the rest is split up depending on system use. Example: File Server If the Linux system you are installing is to be a file server, then your filesystem could look something like Table 2-1. Filesystem Size (MB) Mounted on /dev/sda1 400 / /dev/sda5 2000 /var /dev/sda6 300 /usr /dev/sda7
18、60 Swap space /dev/sda8 1000 /home /dev/sda9 3000 /home/shared Table 1: Example Disk Partition Scheme for a Linux File Server The /usr filesystem is large enough to have Samba installed, as well as X11, if that is desired. Most of the disk space has been allocated to /var, for the log files, FTP and
19、 HTTPD services, to /home, for users own files, and to /home/shared, for common files. Of course, this is only an example. The amount of disk space you allocate for file sharing will depend on factors such as the number of users and the type of files they work on. Linux Swap Space Normally, Linux ca
20、n use a maximum 4GB of swap space. This 4GB can be spread over a maximum of eight partitions. Note that each swap partition is restricted to a maximum of 2GB. There is no authoritative formula for deciding how much swap space should be made, but you can make an estimate based on the typical UNIX rul
21、e of thumb, swap space should be two to three times the amount of RAM. Disk space is very cheap compared to RAM. The maximum amount of memory your system will use is the sum of all of the memory requirements of every program that you will ever run at once. You probably have no idea how much memory y
22、ou absolutely need. You should buy as much memory as you can afford. The price of memory is CHEAP compared to your time in the long run trying to tune an underpowered system. Linux will comfortably run in 32MB of RAM; 64MB is better, while 128MB of RAM and above are magical! Linux was able to addres
23、s 1GB of RAM for systems running with Pentium 1 and below CPUs. Linux kernel 2.2 was able to address 4GB of RAM (using the Enterprise kernel) with newer Pentium II and higher systems. With the new 2.4 kernel in Red Hat 7.1, Linux has extended its memory capabilities on Pentium II and higher systems
24、to 64GB of RAM. The total amount of addressable space for any one program to use is the sum of available RAM and swap space. In general, Linux utilities are usually small but for something like a database service, which can load huge tables into memory and might possibly use all the available memory
25、 while doing so. The same goes for video productions, high-end graphics applications that create cartoons and GIS systems to name a few. You must have some swap space, as suggested earlier; two to three times the amount of RAM is common. Linux actively uses swap as additional RAM space for programs-
26、and not just when physical memory is full. Pages of memory that havent been used for a significant amount of time will be swapped out in an attempt to utilize as much physical memory as possible. Essentially, you do NOT want your system to be using swap consistently. You should add more RAM if swapp
27、ing is being used heavily. Swap space is on disk, which runs five to six orders of magnitude slower than RAM, so it is a significant performance hit. That said, you still must have swap space for those unexpected events when the system needs more memory space. Keep in mind, too, the installation wil
28、l attempt to put the swap partition close to the front of the disk for whatever speed improvement it can get. Another way to speed up swapping is to place swap partitions strategically. You arent limited to having one swap partition in one place. This is especially useful if you are using more than
29、one hard disk on more than one controller. You could put some swap space on a hard disk on each controller. If one controller is busy, then another can be used for swapping. Also, where you put the swap space on the hard disk can affect performance. If the data being used most often is at the beginn
30、ing of the disk, but your swap space exists at the end, the drive has to work harder to move between the data and swap space. Keeping your swap space close to your “busy“ data will result in more efficient use of your hard drive. BIOS Limits Be aware that some computers, built before 1998, may have
31、a BIOS (Basic Input/Output System) that, at bootup (under DOS), limits access to hard disks beyond their 1024 cylinder. A common effect of this problem is your computers inability to see any partitions past the first 512MB of disk space at boot time. If this limitation affects your computer, do not
32、place any bootable partitions after this barrier or the BIOS will not be able to access them and your Linux operating system will not be able to load. Partitioning Utilities There are many disk-partitioning utilities for Linux-even utilities that do not run under Linux. Two of the main utilities tha
33、t come packaged with Red Hat 7.x are fdisk/cfdisk and (during the installation steps only) Disk Druid. (Note: cfdisk is similar to fdisk, but with a full screen interface). They all work towards the same end, but Red Hat recommends you use Disk Druid during the installation. It is safer to use than
34、fdisk, and it has a graphical interface that makes its use easier. Both fdisk and cfdisk are available once Linux is installed. Partitioning Naming Conventions UNIX is notorious for creating weird file names for hardware, and no one standard has been used by all the UNIX versions. Linux, meanwhile,
35、has been using a simple standard for disk drives: disk device names have three letters, then a number. The first letter identifies the controller type (h is for IDE/EIDE, s is for SCSI). The second letter is d for disk, the third letter is for the sequential disk controller starting with “a.“ This m
36、eans the first IDE drive would be hda, the next would be hdb, then hdc and hdd. The partitions are numbered starting from 1, but due to the DOS world, they may not be sequential, depending on how they were created. Under this rule, the partitions would be /dev/hda1, /dev/hda2, /dev/hda3, ./dev/hda16
37、 for the first IDE drive, then /dev/hdb1./dev/hda16 for the second drive, and so one For SCSI drives, the name is sda for the first disk on the first controller. The partitions are /dev/sda1, /dev/sda2. /dev/sda15 (only 15 maximum partitions with SCSI, whereas IDE can have 16). The second disk on th
38、e same SCSI controller would be sdaa1,2,15, and so on. The second controller would have sdb1-15 for the first disk, then sdba1-15 for the second disk on the second controller, and so on. In RH 7.x, there are 2048 configured SCSI devices. The number of disks and partitions already configured depends
39、on the version and distribution of Linux. Exercise 2-1 Partitioning Exercise Although you probably have never had to do this on a basic MS Windows-oriented computer, for a real server system, one thats Windows- or UNIX-oriented, you should pre-plan your disk usage and partitions very carefully. On a
40、 piece of paper, draw a rectangle to represent each hard drive on your computer. Label them in order just as Linux would (e.g., Hard Drive 1: /dev/hda, Hard Drive 2: /dev/sda, Hard Drive 3: /dev/sdb). Use this diagram to plan your Linux partitions visually. Using this method, you can organize your d
41、ata, keeping system or users files together, as well as strategically plan where to place your swap partition(s). CERTIFICATION OBJECTIVE 2.02 Intel CPU Hardware Selection and Configuration You have to be very careful not to choose any hardware that Linux does not yet support. Unfortunately for Linu
42、x, hardware manufacturers are still targeting the Microsoft Windows market. In order for hardware drivers to come available for Linux, either the manufacturers have to recognize the Linux market and produce drivers, or a third party has to do it. The latter brings up one of Linuxs strong points. The
43、re is a vast community of Linux users, many of whom produce drivers for Linux and distribute them freely on the Internet. If a certain piece of hardware is popular, you can be certain that Linux support for that piece of hardware will pop up somewhere on the Internet and will be incorporated into Li
44、nux distributions, such as Red Hat Linux. Be careful when purchasing a new computer to use with Linux. Though Linux has come a long way the last few years, and you should have little problem installing it on most modern PCs,. you shouldnt assume Linux will run on any PC, especially if it is a laptop
45、 or some new state-of-the-art machine. The latest and greatest existing technology may not be supported under Linux (not yet, anyway). The hardware may also be targeted for specific operating systems and configurations. Winmodems and Winprinters are examples of hardware that will not work with Linux
46、 because they are targeted for MS Windows. Integrated hardware (e.g., video chips that share system RAM) and parallel port devices (other than printers) are other pieces of hardware you should be wary of. While there may be ways to make these types of hardware work, the process of actually making th
47、em work may cause more frustration than theyre worth. Last years model is an ideal choice; it is cheap and more likely to be supported. When it comes to laptops, your chances are best with brand names. Unless it has been proven that Linux will run on a newer machine, choosing an older model might be
48、 a better choice. Linux will run very well on lower-end computers. This is one of Linuxs strong points over other operating systems, such as Microsofts Windows NT. Linux runs fine on 32MB of RAM, although more is always better, especially if you want to run any applications. Hardware Compatibility Y
49、ou are not left without help or resources when choosing the right hardware for Linux. There are many places you can turn to for help, including mailing lists and newsgroups. Perhaps the best places to look are the LDP (Linux Documentation Project) or the Red Hat Hardware List. The LDP is a global effort to produce reliable documentation for all aspects of the Linux operating system, including hardware compatibility. Within the LDP, you can find the Linux Hardware HOWTO. Linux Hardware HOWTO The Linux Hardware HOWTO is a document listing most of the hardware components supp
