Installation Objectives to be aware of Unix installation

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 Ins tru cti o ns

Allocating Disk Partitions • Protect the root file system / /usr keep as small as possible (includes /dev, /etc) make sure you leave enough room for /tmp when in single user mode separate, as big as required allow for growing space • Separate out subsystems /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 /var /tmp user home directories mail, printing, log files, etc. temporary file space • The swapfile always requires a separate disk or partition Special filesystem in Red. Hat

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