Linux/FreeBSD/Unix general Installation

• Objectives– 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

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

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

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

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

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 partitionSpecial filesystem in RedHat

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

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!

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