SLAC National Accelerator Laboratory

Installation of Red Hat Enterprise Linux 6

SLAC Computing
Linux at SLAC
Updated: 09 Nov 2011

There are several steps to setting up a fully-integrated Red Hat Enterprise Linux 6 (RHEL6) system at SLAC National Accelerator Laboratory:
  1. Before you Begin
  2. Install Red Hat Enterprise Linux 6
  3. Post Install
  4. SLAC Configuration
  5. Rescue from your CD iso image
  6. Known Issues

Please note: These are not complete Red Hat Enterprise Linux install instructions; go to the Red Hat Web site for more complete information.

Before you Begin

      System Requirements

      These instructions are for installing Red Hat Enterprise Linux 6 (RHEL6) on an IA-32 system (i.e., a 32-bit Intel- or AMD-based system) and Opteron 64-bit systems (x86_64).
      Minimum Memory
      Red Hat recommends for 32 bit a minimum of 1GB memory/logical CPU, and for 64 bit a minimum of 1GB of memory, 1GB/logical CPU. At SLAC, RHEL6 has been successfully installed on systems with 512 MB, but such systems have a tendency to bog down badly due to excessive swapping when too many applications are open at once.
      Minimum Disk Space
      OCIO recommends a minimum disk size of above 12 GB, and a minimum root partition ("/") size of about 9 GB.
      CDROM Drive
      Red Hat does not include a floppy version of the boot images for RHEL6. Your system will need a boot-capable CDROM drive, or a BIOS which knows how to PXE boot (ask unix-admin about that if you have questions).

      Preparing to Install

      1. Consider submitting a request to have OCIO do the installation for you.
      2. Have previous experience installing Red Hat Linux, or else read the Red Hat Install document.
      3. Have an IP address and node name for your system. If necessary, request an IP Address and Node Name from your Desktop admin.
      4. Have available the network and host information required by a Red Hat Linux install, which includes (but may not be limited to): IP address, gateway, netmask and DNS server (provided by your Desktop admin when you obtain your IP address); video card/monitor specs (including size of video RAM); disk drive size; etc.
      5. If you are an experienced Linux user and intend to retain some responsibility for administering your system, you may want to familiarize yourself with Taylor before beginning. This is the tool OCIO uses to adapt systems to the SLAC environment and we strongly encourage you to use it.
      6. If you are installing on a machine that was previously taylored, you should print a copy of the file /etc/taylor.opts before beginning.

      This procedure does a "clean install", not an upgrade. If you follow OCIO recommendations against storing permanent data on a workstation's system disk, this should not be a problem. If you do have some data you want to preserve on this disk, but it is all stored in a non-system partition, e.g., /u1, you might be OK, providing your system partitions are large enough to accommodate RHEL6 with sufficient room for future updates (see Disk Partitions, below). Otherwise, it is your responsibility to backup your data before beginning the installation. If you must restore it to a local filesystem after the installation, we strongly urge you to buy a second disk and keep permanent data off the system disk.

      You may want to work next to a machine with a web browser and access the Red Hat installation manual from the documentation area of the Red Hat web site.

      Install Red Hat Enterprise Linux 6

      The installation program is mostly self-explanatory if you have installed UNIX or Linux before. We will only mention either complex or SLAC-specific issues below.

      Create an Installation CDROM

      To make a bootable CDROM for installing RHEL6, you will need to burn an ISO 9660 image file onto CD-R (or CD-RW) media. On Linux, you can use an application like Xcdroast (requires X Windows) or cdrecord (a command-line tool). On a RHEL5 desktop system, double clicking on a file ending in ".iso" will bring up a "Write to Disk" dialog box which can be used to burn a copy of the file to a CD-R disk. Mac OSX can successfully create bootable CDROMs using the CDROM burning utility.

      To create an installation boot CDROM under Linux, using the cdrecord utility:

      1. Find the ISO 9660 disc image for an installation boot CDROM for your architecture and the current RHEL6 Update level:

        for 64-bit

        RHEL 6 ISOs via http

              Older info:
              cd /nfs/slac/g/scs/redhat/RedHat/RHEL6/6u1/workstation/x86_64/bootiso/
              ls rhel-workstation-6.1-x86_64-boot.iso 
        for 32-bit
              cd /nfs/slac/g/scs/redhat/RedHat/RHEL6/6u1/workstation/i386/bootiso/
              ls rhel-workstation-6.1-i386-boot.iso

      2. Put a blank CD-R (or CD-RW) disc into the CDROM drive.
      3. To get information about your CDROM drive, run the command:
              cdrecord -scanbus dev=/dev/hdc
        You'll get a line that includes some text identifying your specific CDROM device, along with the device address; for example:
              1,0,0   100) '_NEC    ' 'CD-RW NR-9300A  ' '105B' Removable CD-ROM
        The first field in this example, "1,0,0", is your CDROM device address. This is the information you'll need.
      4. Run a command like the following:
              cdrecord -v -speed=2 dev=1,0,0 -eject -data boot.iso
        On some systems you may need to prefix the device address with a transport layer indicator, such as 'ATA:' or 'ATAPI:', or you may need additional options on the cdrecord command line. See the man page for cdrecord for details.

        If you haven't burned any CDROMs before, it's a good idea to run some tests first by adding the '-dummy' option to the cdrecord command line.

      The ISO image for RHEL6.1 includes a 'Rescue' option.

      See below For Rescue Method instructions.

      Boot the Installation Program

      Stick the CDROM in the drive and reboot your machine.

      If your machine ignores the CDROM at boot time, and simply reboots the existing system on the hard disk, there is most likely a problem with the boot order in the BIOS. You can usually get into the BIOS by pressing a function key (usually F2) early in the boot process. The various BIOS screens vary quite a bit, even within a single vendor's products. However, there is usually a place where you can specify the order in which the BIOS should look for a bootable device. You should make sure it looks at the CDROM drive before the hard disk.

      At the introductory, 'Welcome to Red Hat Enterprise Linux 6.1!' menu, choose 'Install or upgrade an existing system'. Other possible choices include 'Install system with basic video driver', 'Rescue installed system', 'Boot from local drive' , or a 'Memory test.'

      N.B.  If your initial installation attempt fails with a wonky video display, retry with the 'basic video driver'.

      N.B.  There may be some variations in the order of the screens in the installation program depending on your exact hardware configuration and/or the choices you make, so it's probably a good idea to read through the rest of this section before proceeding.

      It will take a minute or two to load. Choose 'Skip' to skip the media test.

      Next, after questions regarding 'Language' and 'Keyboard' choice, the installation proceeds to "Installation Method."

      NFS Install Method

      In the "Installation Method" screen, choose NFS directory to insure that the latest SLAC-recommended kernel and RPMs are installed. If you install from a CDROM, you may need to upgrade the kernel after installation in order to comply with SLAC security requirements.

      Next, you will be asked to configure TCP/IP.

      Under Enable IPv4 support Uncheck Use dynamic IP configuration by checking the Manual Configuration. Uncheck Enable IPv6 support. (Movement and select directions are at the bottom of the screen).

      On the next screen "Manual TCP/IP Configuration" enter the IP Address, Netmask, Default gateway and Primary nameserver information given to you by your Desktop admin when you requested your node name and IP address. The primary nameserver is


      Please be careful to enter this information accurately, because errors can disrupt the network.

      Next you will enter NFS setup information. The NFS server name is and the Red Hat directories are:

      • For Opteron and EMT64 systems: /gpfs/slac/staas/fs1/r/g.scs.redhat/RedHat/RHEL6/6u4/x86_64.
      • For all other systems(Pentium, Athlon, etc.): /gpfs/slac/staas/fs1/r/vol/vol1/g.scs.redhat/RedHat/RHEL6/6u4/i386.

      If the directory can't be mounted, try using the fully qualified hostname (including like this: You could also try using the IP address by doing a 'nslookup' or 'host' command to find the current IP address of lnxinstall.

      Introductory screens

      Note: If you want to capture a particular screen display in the installation, to refer to later, you can press 'Print'+'Shift'. The screen copy will be stored in /root/anaconda-screenshots/ for you.

      After the splash RHEL6 screen, the next questions are:

      • What type of devices will your installation involve. Choose 'Basic Storage Devices'
      • If an existing installation is discovered on the system, you'll be asked if you want a 'Fresh Installation' or 'Upgrade an Existing Installation'. Either way, assuming you have backed up any important files, choose 'Fresh Installation'
      • The 'Please name this computer' should be auto-filled in. You should not need to 'Configure Network'
      • Please select the nearest City in your time zone The root password screen. Choose a good root password and DON'T FORGET IT! SLAC's post-installation tool taylor will override this password.

      • 'Which type of installation would you like?' Choose 'Create Custom Layout'

        The default partitioning scheme used by the the other options is not suitable for use in the SLAC environment.

      Disk Partitions

      The table below shows suggested partitioning schemes for two different size disks, representing typical sizes of disks available on older hardware still in service here at SLAC. Newer systems usually have substantially larger system disks.

      Make sure to give Linux at least a 9 GB root partition. If your root partition is less than about 9 GB, you should omit installing some of the software package groups recommended below, in order to allow room for future upgrades and security patches. Similarly, if you install more package groups than suggested below, you will probably need a larger root partition -- perhaps 10-12 GB if you install nearly everything. Small root partitions can make it difficult or impossible to install required security patches later on. Systems that cannot apply required security patches in a timely fashion may be denied access to the SLAC network. If possible the root partion should be at least 20 GB for modern machines with 100 GB and larger disks.

      You should also create a swap partition at least as large as the memory (twice the main memory is a good rule of thumb for the size of the swap partition).

      If there is sufficient space, we recommend that you allocate an /scswork partition of 1 GB, to be reserved for the exclusive use of OCIO. Use the rest for scratch space; for example, you might want to create a larger /tmp or add a separate /scratch directory. Note that older files in /tmp are periodically removed but files in /scratch will remain until removed by you unless the system is re-installed.

      Always choose to format your Linux partitions. Use the new, ext4 filesystem type on all partitions except swap and /usr/vice/cache/cache.. (In earlier versions of AFS, /usr/vice/cache needed the ext2 filesystem, but ext4 is now compatible with the AFS cache). ext4 is a journaling filesystem and will permit much faster recovery following crashes.

      WARNING! You should not allocate any partitions on the system disk for permanent data. Because of the large sizes of currently available disks, you may be strongly tempted to ignore this warning. However, it is very risky to do so, because:

      • we do not backup the data on local disks attached to workstations;
      • the disks installed in workstation-class machines are much less reliable than those we buy for our fileservers; and,
      • our support model assumes that it's OK to repartition and re-install the system disk on short notice.

      The best way to make use of extra space on your system disk is to allocate a large /tmp or /scratch partition. If you need additional permanent space, please contact; we will do our best to help you acquire reliable, backed-up storage at a reasonable cost. If you ignore this warning, it will be your responsibility to save and restore your data the next time your system needs to be re-installed.

      Note that partition names and numbers, and the order of the partitions, are assigned automatically. Also, the actual sizes of allocated partitions may vary a little bit from what you request in the GUI interface. This may make it difficult to allocate every last block on the disk. The OCIO recommendation is to use LVMs and to leave extra room which can be used later.

      Suggested partition schemes for typical hard disks:
      Mount Point
      Partition Size
      12 GB disk +18 GB or larger disk
      / ext4 9 GB 12 GB
      swap swap 1 x memory or
      at least 512 MB
      2 x memory or
      at least 1 GB
      /var ext4 512 MB 4 GB
      /usr/vice/cache ext4 512 MB 2 GB
      /tmp ext4 512 MB 4 GB
      /scswork ext4 omit 1 GB
      /scratch (or extra /tmp space) ext4 omit remainder

      When you begin, you'll have a screen that appears this way:

      Start edit partition sda1
      When you are done, You'll have a configuration something like this:
      Finish edit of  partition sda1

      There will be two dialog boxes confirming you want to reformat the disk.

      Boot Loader Configuration

      Accept the defaults for the other options on this screen.

      Selecting Installation

      As stated by the installer, 'The default installation of Red Hat Enterprise Linux is a desktop install.' Other choices include, 'Minimal Desktop', 'Web Devlopment Workstation', 'Software Devlopment Workstation', and 'Minimal' Please do not install the 'Web Development Workstation' unless you really know what you are doing and okay it with OCIO first.

      Don't worry too much about getting every package you might ever want -- you can always add additional packages later.

      After this, the installation will begin. It may take 15 minutes to over an hour to install the packages depending on the speed of your machine and network.

      Once complete, you'll be presented with a 'Congratulations' screen. NOTE you'll want to eject your boot CDROM prior to rebooting so you don't boot back to the boot iso image.

      The final installation screen has a 'reboot' bottom on the right corner. Again, make sure to remove any CDROM left in the drive from the initial boot of the installation program.

      Post Install

        Red Hat Welcome

        The first time you boot your newly-installed system in the graphical run level (run level 5) the Red Hat Welcome screens may automatically run.

        If you are planning to taylor your system you can skip most or all of these steps -- they are either unneeded or will be handled by taylor.

        The welcome screens are intended for stand-alone systems and guides you through a number of first time system administration tasks such as:

        • License Information
        • You'll need to agree to the License agreement.

        • Set Up Software Updates
        • If running Taylor, then choose 'no'. (You'll need to confirm 'No Thanks'.)

        • Create User, (a non-admin local account)
        • In particular, avoid creating a local account with the same username as your SLAC UNIX account or registering personally with RHN. If you plan to taylor the system, you do not need to create a local account. Please do not. For the Create User screen 'Forward' button with no additions or adjustments. You'll need to confirm you want to continue without a user account.

        • Date and Time
        • Accept the defaults.

        • Kdump
        • Accept the defaults. Do not choose to reboot to enable kdumps.

        On the next screen, you'll click on 'Other..' enter 'root' as the user and password you picked earlier. You'll see messages related to being logged in as root, and how it's not ideal, but this okay for this one time. You'll also see missing entitlements messages.

        SLAC Configuration

          WARNING: This is not (yet) for laptop users.

          Taylor is the tool used by OCIO for administering the very large number of UNIX (including Linux) systems for which we are responsible. It can be run after the Red Hat installation program to automatically configure your new system to be integrated into the SLAC environment. It normally installs a cronjob which will maintain your system automatically.

          Some of the things Taylor does include:

          • Configure the network interfaces for the correct subnet at SLAC.
          • Set up network services such as NIS, DNS, NTP, and syslog correctly.
          • Install or update recommended software, including AFS, AMD, SSH, and LPRng.
          • Update the passwd and groups files to include OCIO-required system accounts and to permit login by users via their regular SLAC UNIX accounts (this can be restricted after Taylor runs the first time).
          • Configure sendmail for SLAC's email environment.
          • Install LPRng to centralize printing.
          • Install some TrueType fonts.
          • Remove or reconfigure some insecure services.
          • Install sudo with a centrally-managed sudoers file (sudo is a UNIX tool to allow users to issue privileged commands).
          • Install and run yum to get updates.
          • Optionally, setup /usr/local to point to SLAC AFS /usr/local for Linux.
          • Install an hourly Emergency cronjob that can be used, for example, to apply urgent security fixes.
          • Install a nightly Taylor cronjob to apply routine maintenance to your system automatically (this cronjob can be removed, and Taylor re-run by hand from time to time, on mission-critical servers).

          For additional information, see the Taylor Web page.

          Running Taylor

          Taylor uses a configuration file, /etc/taylor.opts, to control its actions. If you don't have this file the first time you run Taylor, it will install one with a reasonable set of defaults. However, you may want to set some of these options before you run Taylor the first time, since the root password you set during installation will otherwise be overridden at this point.

          If your machine was previously taylored, you will most likely want to restore most or all of the options from your old taylor.opts file (you did print a copy before beginning, right?). If your machine is connected to a non-autonegotiating (fixed speed) 100 MB/s port, it is particularly important to include the option, ethernet=100mb. If you are not sure, omit this option or check with net-admin or your Desktop Admin.

          If your machine has not been previously taylored, look in /afs/slac/package/taylor/taylor.opts for a sample taylor.opts file. In particular, this file includes commented out examples examples showing how to:

          • Control the root password
          • Select a graphical or text-mode login
          • Request a private /usr/local directory

          For a more complete list of options, do man taylor.opts.

          After running Taylor the first time, if you subsequently need an option changed and can no longer modify /etc/taylor.opts yourself, contact one of your Linux Desktop Support people or send mail to unix-admin.

          First get to a terminal prompt from the GUI by selecting from the top left of the menu bar "Applications", then 'Systems Tools" and lastly 'Terminal'.

          To install and run Taylor, execute the following command:

          wget -O- | sh

          You will be asked whether to use the version of /usr/local maintained by OCIO or set up a private /usr/local. We highly recommend that you use the central one.

          After you are done, on the next reboot you'll be asked if you want to update standard folders to current language.

          Taylor will probably take several minutes to complete its work. If there is an error and you can see how to fix the problem, it is safe to rerun taylor afterward. If you have an error you cannot understand or fix, send email to unix-admin to request help. If possible, paste the error messages from Taylor into the email.

          Access to SLAC's MAIL Spool and other NFS servers

          If you receive your email via the UNIX mail spool rather than SLAC's Exchange server, you'll need access to /nfs/mailspool/mail/<your_UID>. Some users may also want to access other central NFS file servers from their Linux workstations. Access to NFS is not automatic; for security reasons you must submit a request to OCIO for permission to mount our central servers. There is a simple NFS Access form for this purpose if you do not need any superuser privileges on the machine. If you also need privileges, see the next section.

          Superuser Privileges

          If you need superuser privileges (i.e., the root password and/or sudo ALL) on your machine, you will need to carefully read the Superuser/NFS Privileges page, then fill out and submit the form you'll find there. If you also need NFS access, you must request it via this same form.

          SLAC's RPM Repository

          SLAC maintains a mirror of the Red Hat Enterprise Linux WS 6 distribution on a RedHat Linux Satellite Server.


          The yum command is a program that can look at a directory or at an ftp or http site and determine if there are updates to any of your packages there. If it finds them, it can also install them. Taylor installs yum and uses it to apply required security updates. In addition, Taylor configures yum so that you or your system admin can use it to install any necessary bug fix RPMs to bring your system up to the latest OCIO-recommended Red Hat update level. The command to do this is simply,

             sudo yum upgrade
          To find out what yum would do without actually doing it, use the command, sudo yum check-update.


          Use the GUI program:

             sudo gpk-application
          to find additional RPMS that you might want to install (the program is from the gnome-packagekit RPM). You can also find this program in Gnome under the System menu, then under the Adminstration menu, then "Add/Remove Software".

          Rescue from your CD iso image

          1. Boot as you do above in the installation section
          2. Select Rescue from Menu of choices
          3. Choose a Language
          4. Choose Keyboard Type
          5. For Rescue Method - Choose NFS directory
          6. Configure TCP/IP - Manual configuration
          7. Give it the path as defined in the install section
          8. Choose continue step
          9. This will mount your system under /mnt/sysimage
          10.    - as stated - after pressing [return] to get a shell, you can 'chroot
               /mnt/sysimage' to make your environment the root environment. And you are in as root

          Known Issues

            There are some known issues with RHEL6. Please see the RHEL6 Release notes for other information:
            Release Notes

            More Information

            Join the SLAC Linux mailing list to exchange information and advice with other users. There is a convenient Web page for subscribing or reviewing the archives or you can send mail to with the first line of the body being "subscribe linux-l".

            If you need more information, please have a look at our Linux Resources page.