Installation Objectives Contents Practical Summary to be aware of Unix installation issues Contents installing the system options and packages disk layout the swapfile third party software Practical none Summary

System Installation Each manufacturer has different of installing the system All follow the same basic principles boot a small stand-alone Unix system called miniroot partition the hard disk copy in basic Unix system boot system from hard disk install remaining software Modern Unix is easy to install installation is a series of simple questions default answer are provided for most questions installation often auto-detects installed hardware Many systems come pre-installed Manufacturers adopt different mechanisms for installing software. All mechanisms follow the same basic procedure. Some manufacturers are very good at helping novice users; the PC systems probably assume the least amount of knowledge and experience from the user. Some older Unix systems expect a high level of knowledge in order to install the system; fortunately these systems are few and far between and are improving all the time. Most systems have easy, menu-driven installation procedures. Some start up automatically when the system is booted, others have to be run from the command line (single-user mode, stand-alone system). Older systems may require the user to work through a series of programs performing the installation from the basic utilities.

Options Unix installation is usually split into a number of options you install those options you want or have paid for Examples: base you need this networking TCP/IP and NFS - sometimes two separate options development C compiler and associated utilities If you do not install initially, you can easily install later Most of this software will be put in /usr so leave room in /usr for any likely expansion High level options often split into packages packages can be selected independently be aware of inter-package dependencies To simplify pricing and packaging most systems now install as a series of options or packages. You simply pay for the options you want and install accordingly. Sometimes the options come on separate media and sometimes you need serial codes and keys to install the options. Always keep all software/hardware delivery notices and supplementary information close at hand when installing the system.

Before Installation Read any installation instructions Read installation instructions again Determine system configuration how much memory how much hard disk space other specific hardware information (irqs, etc.) Decide which software options are required work out disk partitioning allow disk partition for swap space Think of a name for your system get an IP address if appropriate Before starting the installation, read any instructions. Skip over the hard or boring bits to get a feel for what is required. Read the instructions again, taking more care to get a better picture of the installation process. Try and leave at least one day between each reading to let the ideas sink in. Don't rush into installing a new system if you've never done it before. Take your time, read the manuals and installation instructions and think about what you learn. Getting the root and swap partition sizes correct is important. Most systems will not allow these partition sizes to be changed without reinstalling the system. Many systems will not allow any disk partitions to be changed without reinstalling the entire disk.

Additional Installation Information Most installation questions are hardware related check your delivery documentation to what was ordered/delivered Monitors installations often want to know monitor make & model sometimes your need to know size/resolution/refresh rates Keyboards check the key layout make sure you know the difference between US and SE keyboards Time zone in Sweden your time zone is CET (may be part of Western Europe) Disks how many have you got how do you want to partition them Most installations ask the same sort of questions. Make sure you are aware of your requirements for the areas shown on this slide.

The First Installation Plan on installing the system twice First time just accept defaults for all questions at least the ones you can't obviously answer Boot the installed system and see how it looks you never know it might be right first time Take your time with the second installation think about what you want and what you learnt first time If you've never done an installation before just give it a go and accept the defaults to any questions the install script asks. You will almost certainly end up with a working Unix system. You may not be able to access all the hardware and your disk partitioning may not be the best but at least you can look at the system. Plan on taking the second installation more slowly and think about what you want the final system to look like. Instructions

Allocating Disk Partitions Protect the root file system / keep as small as possible (includes /dev, /etc) make sure you leave enough room for /tmp when in single user mode /usr separate, as big as required allow for growing space Separate out subsystems /boot bootable programs /usr/local third party software /var special formats such as "raw" databases Use disk partitions to limit sizes of key file systems which have a tendency to grow /home user home directories /var mail, printing, log files, etc. /tmp temporary file space The swapfile always requires a separate disk or partition Special filesystem in RedHat Separate disks and disk partitions can be used very effectively to increase the robustness of a Unix system. However, it may take a number of iterations to get the exact balance of file system size (disk partition size) against functionality. Overly large disk partitions waste space, small ones prevent the system working effectively. The easy solution is to allocate one large partition across each disk and allocate the files within the constraints of the disk sizes. A good system administrator will use partitions to limit file growth within notoriously bad areas (such as user home directories and spool files). Limiting known problem areas will prevent the root file system from filling up. If the root file system fills up, the Unix system will be unable to continue to work and will probably lock up, forcing the administrator to crash the machine deliberately in order to reboot to single-user mode and correct the problems. The directories on this slide (excepting /usr) are used to hold data files created by the users. Protect the system (and users) from the small minority of users who generate large amounts of data by limiting the size of these file systems. The /var file system is part of the SVR4 standard, but older Unix systems do not have this directory, and different directories have to be separated out on these systems. The root file system should contain spare room for temporary files created whilst in single-user mode when other file systems are not normally mounted. There is nothing wrong with mounting a larger file system on /tmp when in multi-user mode.

The Swapfile The swapfile is disk space for memory pages pages swapped out of memory to this file new code or data can be loaded into the free'd memory page The swapfile is a non-filesystem (raw) disk partition usually on the boot disk size varies between manufacturers: typically 2 or 3 times real memory The swapfile is fixed in size get it right first time or oversize the swapfile for possible extra memory reinstall the system to increase the swapfile partition Use swap to allocate temporary swap space can specify a file in the Unix filesystem as extra swap space slower than a true swapfile but may be better than reinstalling the system Unix requires a swapfile to be allocated on a disk partition of its own. Once setup the swapfile cannot easily be changed on most systems. Usually you have to reinstall the system to increase the swapfile size.

Tmp on Swap Many Unix systems can overlay /tmp on the swapfile swapfile is large and not heavily utilised system manages allocation of swap space or temporary files many only apply in multi-user mode Beware of creating large files in /tmp /tmp used by vi for temporary working buffer Beware of systems which link /var/tmp to /tmp You cannot create new processes if the swapfile is full Files written to /tmp will not persist across reboots you shouldn't be using /tmp for important files anyway! Modern Unix does not make much use of the swapfile but still requires a large amount of swap space to be allocated. To make better use of the available disk space many Unix systems map the temporary directory onto the swapfile.

Summary Unix installation is a simpler then it used to be PC Unix can be problematical Most systems install through a menu driven question and answer script Some systems can auto-detect hardware and install themselves with almost no user interaction Many systems are shipped pre-installed There are no standards for installing third party software