EXPERIMENTAL Xen guest domain installation for SLC 3.0.8 / i386

PLEASE NOTE: This is Work In Progress and NOT production quality release: it may or may not work for you ... remember: if it breaks you have to keep both pieces ... and YMMV ..

This installation procedure concerns ONLY para-virtualized Xen guest systems.

This installation procedure was tested ONLY with SLC3.0.8 'CERN Recommended Setup' default installation type.

PLEASE NOTE: Since support for SLC3/x86_64 and SLC3/ia64 architectures ends December 2006 Xen guest systems will NOT be provided for these architectures.

Installation instructions

• edit /etc/xen/SLC308guest configuration file

     name = "SLC308guest"
     memory = 512
     #vcpus = 2
     disk = [ 'file:/somewhere_somefile.img,sda,w' ]
     vif = [ 'mac=00:16:3E:XX:XX:XX' ]
     #bootloader="/usr/bin/pygrub"
     on_reboot   = 'destroy'
     on_crash    = 'destroy'
     on_poweroff = 'destroy'

(create /somewhere_somefile.img with dd , at least 5GB needed.. see PreparingXenGuestFilesystems for a more detailed description how to prepare guest filesysems)

NOTE: for SLC 3.0.8 para-virtualized guest ONLY A SINGLE sda virtual disk is supported (after installation additional devices may be added to the system)

NOTE: MAC address should start with 00:16:3E - this is Xensource reserved range allowed for public Xen-related usage. And you will need to register this machine in advance in LanDB, and probably need to ask Netops to change the existing entry for the hypervisor machine to become a "Fanout".

Starting the guest installation

• download installation kernel and ramdisk from:

  http://linuxsoft.cern.ch/cern/slc308/i386/images/xen/

• run:

      /usr/sbin/xm create SLC308guest -c \
                 kernel=vmlinuz \
                 ramdisk=initrd.img \
                 extra="method=http://linuxsoft.cern.ch/cern/slc308/i386/ ramdisk_size=16384 serial skipddc"

NOTE: serial IS needed , or installer will crash on hardware detection, skipddc IS needed, or kernel will crash on hardware detection.

NOTE: If your dom0/hypervisor system has SELinux enabled and you get errors about vmlinuz or initrd.img not being found despite seeing them via ls (e.g. after downloading them into /tmp or /root), you may run into SELinux trouble (/var/log/messages may have some "_avc_" entries in this case). Use

chcon system_u:object_r:etc_t     initrd.img vmlinuz

to label the files with a context that is accessible by xend, neither /tmp nor /root are readable for xend. Or copy (not move) these files to a different directory.

The installation procedure looks exactly the same as standard SLC3 installation on real hardware.

Post installation setup

• after installation finished edit /etc/xen/SLC308guest again

     name = "SLC308guest"
     memory = 512
     #vcpus = 2
     disk = [ 'file:/somewhere_somefile.img,sda,w' ]
     vif = [ 'mac=00:16:3E:XX:XX:XX' ]
     bootloader="/usr/bin/pygrub"
     on_reboot   = 'restart'
     on_crash    = 'restart'
     on_poweroff = 'destroy'

Running the guest domain

• To start the guest run

      /usr/sbin/xm create SLC308guest (-c)

Automatic startup of guest domain

• if you want the domain to be (re)started by Xen automatically:

     /bin/ln -s /etc/xen/SLC308guest /etc/xen/auto/

Finalizing guest domain setup

After guest domain reboots it will have configured additional apt repository for Xen-enabled kernels/glibc .. etc. (SO PLEASE ignore the warning about /lib/tls on first boot , just check that after update you have glibc-X.Y.Z.xen installed)

Since the graphical installer is not supported in virtualized guests for now, you will have to configure your system for CERN setup manually:

   /usr/sbin/lcm --configure --all
   /sbin/chkconfig --levels 345 afs on
   /sbin/service afs start
   /usr/sbin/lcm --update

Also disable the CPU microcode update (after all we are running on virtual CPUs ...) and SMART disk monitoring (we are running on virtual disks too ..). The hardware clock cannot be set either, so NTP is useless on the client (but you want it to run on the hypervisor).

   /sbin/service microcode_ctl stop
   /sbin/chkconfig --del microcode_ctl
   /sbin/service smartd stop
   /sbin/chkconfig --del smartd
   /sbin/service ntpd stop
   /sbin/chkconfig --del ntpd

Management of Xen domains

• Please see XenUserGuide for information.