SGI periodically releases a new version of IRIX, the version of UNIX that runs on Silicon Graphics workstations.  IRIX is the operating system for your SGI, which means that IRIX is the software that handles your computer's overall operation.  The current version of IRIX  is 6.5.   This is the preferred OS for your SGI.  It is SGI's solution for Year 2000 compliance on its workstations and will be fully supported for some time.  The only other supported OS is IRIX 6.2.  This simply means that if bugs are found in 6.2, SGI will attempt to provide a fix.  You are required to have your system running a supported OS for hardware support from SGI. You may want to have 6.2 on your system if you can't upgrade to 6.5 for some reason.   IRIX 6.5 will only work not work on all hardware and it requires 64MB of RAM and a minimum 2GB disk; and in some cases, a full OS upgrade may not be convenient.  There are previous versions of IRIX that are still common: IRIX 5.3, 6.2, 6.3, 6.4.  These are supported for Y2K compliance which is achieved with patches available from SGI.

• 5.3: This was common on old systems, most systems except the oldest(e.g. Power Series, Personal IRIS) should be able to upgrade to 6.2.
• 6.2: IRIX 6.2 can run on most Indigo, Challenge, Indy, and Indigo2 systems.  It can't run on O2's, Origin series or Octanes.
• 6.3: This was a special release for the O2 and has been replaced by 6.5.
• 6.4: This was a special release for the Origin series and Octane.  It too has been replaced by 6.5
• 4.x and other 5.x and 6.x:  These are outdated and haven't been supported in a while.  Unless there's a very good reason to keep a system at one of these releases, you should upgrade to a higher version.

    Since IRIX 6.5 is now the predominant OS, this page will only refer to older versions of IRIX when upgrading from one to IRIX to 6.5.  IRIX 6.5 has some important concepts to understand in its design.  IRIX 6.5 was released as a cross-platform, Y2K compliant OS in 1998.  There were a number of new features included, I think the most important are:

• A new scheme for dealing with bug fixes.  IRIX 6.5 doesn't usually have patches, because an updated version is released usually every 3 months.  The latest update as of this writing is 6, so it would be called IRIX 6.5.6.  These updates are cumulative, so you don't need to apply each update.
• Updates to the OS are classified in two types: 1) necessary bug fixes for system maintenance and  2) necessary bug fixes for system maintenance plus new software features.  These two forms of 6.5.x are 6.5.xm and 6.5.xf respectively.  The first type, the maintenance stream update, incorporates system maintenance fixes and the feature stream update incorporates the maintenance update and new software features for the OS.
• Additional software functionality built-in, such as NFS; old, unneeded capabilities not available.
• The ability to apply an update to the 6.5 software without shutting down to mini-root.  Mini-root is a special OS state for major system changes.

How to install and upgrade 6.5:

    Installing 6.5 could take several pages to explain, and it may change with each update.  There are several SGI links below for going about upgrading to 6.5.   Since it's a major change, I don't recommend doing it yourself, unless you're quite experienced with OS upgrades on SGI's.  Upgrading from 6.5.x to a later version of 6.5 is different since it's been designed to be easier.   This discussion will assume IRIX 6.5.5, but there probably aren't too many differences with 6.5.6.

The latest on 6.5.
Installing 6.5

    It's important to read through this, because things can go wrong. With upgrading or installing 6.5 watch out for:

Before and during the installation:

• You may need to load all 8 CD's listed in the installation manual to install a single product in the 6.5 OS distribution.
• False error message about software unable to be installed.  See the installation information from SGI for more info.  Try adding a "/dist6.5" to the software distribution path.
• SGI's web site has a minimal install that takes up < 1 GB they claim works.  I tried it and it did not work.
• ftn_eoe.sw.libblas is no longer installed by default.  This software is crucial for many scientific programs.  Before typing "go" when installing 6.5, enter "i ftn_eoe.sw.libblas*" to select these sub-systems.
• Conflicts with older versions of NFS when upgrading.  In the conflicts command, you need to choose to remove the old NFS and re-select the new NFS that comes with IRIX 6.5.  Careful, there are two NFS versions you'll be dealing with both with the same name.  Use the product id numbers next to them to determine which is the new one, the larger number of the two.
• Innocuous Appletalk error messages during installation of the feature stream.  See the installation information from SGI for more info.

• While booting up, the system says "unable to config ec0 as hostname".  I believe this is because the 6.5 installation software assumes a subnet mask that is incorrect for my subnet.  I ignore this message, because you can change the subnet mask once the system comes up.  See /etc/ifconfig-1.options (netmask 0xfffffc00 for Chemistry subnets).
• Your graphics will not work after an upgrade to 6.5 if you've added "shnumclients" to your /var/X11/xdm/Xservers file to fix a security problem.
• Networking will mysteriously not startup if your /etc/config/ifconfig-1.options file doesn't have all settings on a single line.
• Problems with /etc/resolv.conf.   There is a new file used for managing different network services, /etc/nsswitch.conf.  /etc/resolv.conf should no longer contain a "hostresorder" line.
• After the installation, be sure to run "versions changed" and look for any files with ".O" suffixes.  These are your old configuration files that have been replaced with new ones.  Run "diff file file.O" or "xdiff file file.O" on graphical systems to go through the files and retain any special config's you had added previously.  /etc/inittab and /etc/group are covered next.
• /etc/inittab has been re-written.  This will cause problems if you had a custom configured /etc/inittab in a pre-IRIX 6.5 version.  Read the man page on inittab to re-install any custom equipment you need.  You can also use the System Manager to install modems, terminals, and other serial devices that depend on /etc/inittab.
• SGI replaces the /etc/group file by default with one that has an additional group in it.  They rename your old one to /etc/group.O.
• IRIX 6.5 turns a DHCP server on by default.  Turn it off by modifying /etc/inetd.conf.  Search for "dhcp" and comment out that line.  See instructions at the top of the inetd.conf file to re-start inetd so this will take effect.
• Sometimes software isn't upgraded properly, or new software won't work.  Double check to see if any essential software products and sub-systems are installed for your product.  Be warned, SGI has a tendency to re-organize software products often and without warning.

• As of IRIX 6.4 and 6.5, sh is no longer Bourne shell, but Korn shell.
• The "Backup" program  uses "cpio" as of 6.5.

    There may be more caveats.   Frequently check SGI's 6.5 web site above for changes.

last updated 2/28/00 by Martin McCormick, martinm@sas.upenn.edu