Diskless (Stateless) Installation

Note

The stateless Service Node is not supported in Ubunti hierarchy cluster. For Ubunti, skip this section.

If you want, your Service Nodes can be stateless (diskless). The Service Node must contain not only the OS, but also the xCAT software and its dependencies. In addition, a number of files are added to the Service Node to support the PostgreSQL, or MySQL database access from the Service Node to the Management node, and ssh access to the nodes that the Service Nodes services. The following sections explain how to accomplish this.

Build the Service Node Diskless Image

This section assumes you can build the stateless image on the management node because the Service Nodes are the same OS and architecture as the management node. If this is not the case, you need to build the image on a machine that matches the Service Node’s OS architecture.

  • Create an osimage definition.

When you run copycds, xCAT will only create a Service Node stateful osimage definitions for that distribution. For a stateless Service Node osimage, you may create it from a stateless Compute Node osimage definition.

lsdef -t osimage | grep -i netboot
rhels7.3-ppc64le-netboot-compute  (osimage)

mkdef -t osimage -o rhels7.3-ppc64le-netboot-service \
           --template rhels7.3-ppc64le-netboot-compute \
           profile=service provmethod=netboot postscripts=servicenode

lsdef -t osimage rhels7.3-ppc64le-netboot-service
Object name: rhels7.3-ppc64le-netboot-service
    exlist=/opt/xcat/share/xcat/netboot/rh/compute.rhels7.ppc64le.exlist
    imagetype=linux
    osarch=ppc64le
    osdistroname=rhels7.3-ppc64le
    osname=Linux
    osvers=rhels7.3
    otherpkgdir=/install/post/otherpkgs/rhels7.3/ppc64le
    pkgdir=/install/rhels7.3/ppc64le
    pkglist=/opt/xcat/share/xcat/netboot/rh/compute.rhels7.ppc64le.pkglist
    postinstall=/opt/xcat/share/xcat/netboot/rh/compute.rhels7.ppc64le.postinstall
    postscripts=servicenode
    profile=service
    provmethod=netboot
    rootimgdir=/install/netboot/rhels7.3/ppc64le/compute
  • Configure mandatory attributes for Service Node osimage definition.

    The following attributes must be modified to suitable value:

    exlist
    otherpkglist
    pkglist
    postinstall
    rootimgdir
    
  1. Create the exlist, pkglist and otherpkglist files.

xCAT ships a basic requirements lists that will create a fully functional Service Node. However, you may want to customize your service node by adding additional operating system packages or modifying the files excluded by the exclude list. Check the below files to see if it meets your needs.

cd /opt/xcat/share/xcat/netboot/rh/
view service.rhels7.ppc64le.pkglist
view service.rhels7.ppc64le.otherpkgs.pkglist
view service.rhels7.ppc64le.exlist

If you would like to change any of these files, copy them to a custom directory. This can be any directory you choose, but we recommend that you keep it /install somewhere. A good location is something like /install/custom/netboot/<osimage>.

export OSIMAGE_DIR=/install/custom/netboot/rhels7.3-ppc64le-netboot-service

mkdir -p $OSIMAGE_DIR

cp /opt/xcat/share/xcat/netboot/rh/service.rhels7.ppc64le.pkglist $OSIMAGE_DIR
cp /opt/xcat/share/xcat/netboot/rh/service.rhels7.ppc64le.otherpkgs.pkglist $OSIMAGE_DIR
cp /opt/xcat/share/xcat/netboot/rh/service.rhels7.ppc64le.exlist $OSIMAGE_DIR

And make sure that your otherpkgs.pkglist file has the following entries:

xcat/xcat-core/xCATsn
xcat/xcat-dep/<os>/<arch>/conserver-xcat
xcat/xcat-dep/<os>/<arch>/perl-Net-Telnet
xcat/xcat-dep/<os>/<arch>/perl-Expect

For example, for the osimage rhels7.3-ppc64le-netboot-service:

xcat/xcat-core/xCATsn
xcat/xcat-dep/rh7/ppc64le/conserver-xcat
xcat/xcat-dep/rh7/ppc64le/perl-Net-Telnet
xcat/xcat-dep/rh7/ppc64le/perl-Expect

Note

You will be installing the xCAT Service Node RPM xCATsn-<version> on the Service Node, not the xCAT Management Node RPM xCAT-<version>. Do not install xCAT Management Node RPM xCAT-<version> on the Service Node.

  1. Create the postinstall script.

xCAT ships a default postinstall script for stateless Service Node. You may also choose to create an appropriate /etc/fstab file in your Service Node image. :

export OSIMAGE_DIR=/install/custom/netboot/rhels7.3-ppc64le-netboot-service
cp /opt/xcat/share/xcat/netboot/rh/service.rhels7.ppc64le.postinstall $OSIMAGE_DIR

vi $OSIMAGE_DIR/service.rhels7.ppc64le.postinstall
  # uncomment the sample fstab lines and change as needed:
  proc /proc proc rw 0 0
  sysfs /sys sysfs rw 0 0
  devpts /dev/pts devpts rw,gid=5,mode=620 0 0
  service_ppc64le / tmpfs rw 0 1
  none /tmp tmpfs defaults,size=10m 0 2
  none /var/tmp tmpfs defaults,size=10m 0 2
  1. Modify the Service Node osimage definition with given attributes.
export OSIMAGE_DIR=/install/custom/netboot/rhels7.3-ppc64le-netboot-service
chdef -t osimage -o rhels7.3-ppc64le-netboot-service \
           exlist=$OSIMAGE_DIR/service.rhels7.ppc64le.exlist \
           otherpkglist=$OSIMAGE_DIR/service.rhels7.ppc64le.otherpkgs.pkglist \
           pkglist=$OSIMAGE_DIR/service.rhels7.ppc64le.pkglist \
           postinstall=$OSIMAGE_DIR/service.rhels7.ppc64le.postinstall \
           rootimgdir=$OSIMAGE_DIR/service

lsdef -t osimage -l rhels7.3-ppc64le-netboot-service
Object name: rhels7.3-ppc64le-netboot-service
    exlist=/install/custom/netboot/rhels7.3-ppc64le-netboot-service/service.rhels7.ppc64le.exlist
    imagetype=linux
    osarch=ppc64le
    osdistroname=rhels7.3-ppc64le
    osname=Linux
    osvers=rhels7.3
    otherpkgdir=/install/post/otherpkgs/rhels7.3/ppc64le
    otherpkglist=/install/custom/netboot/rhels7.3-ppc64le-netboot-service/service.rhels7.ppc64le.otherpkgs.pkglist
    pkgdir=/install/rhels7.3/ppc64le
    pkglist=/install/custom/netboot/rhels7.3-ppc64le-netboot-service/service.rhels7.ppc64le.pkglist
    postinstall=/install/custom/netboot/rhels7.3-ppc64le-netboot-service/service.rhels7.ppc64le.postinstall
    postscripts=servicenode
    profile=service
    provmethod=netboot
    rootimgdir=/install/custom/netboot/rhels7.3-ppc64le-netboot-service/service

While you are here, if you’d like, you can do the same for your Service Node images, creating custom files and new custom osimage definitions as you need to.

  • Make your xCAT software available for otherpkgs processing

    Option 1:

    If you downloaded xCAT to your management node for installation, place a copy of your xcat-core and xcat-dep in your otherpkgdir directory

    lsdef -t osimage -o rhels7.3-ppc64le-netboot-service -i otherpkgdir
    Object name: rhels7.3-ppc64le-netboot-service
        otherpkgdir=/install/post/otherpkgs/rhels7.3/ppc64le
    cd /install/post/otherpkgs/rhels7.3/ppc64le
    mkdir xcat
    cd xcat
    cp -Rp <current location of xcat-core>/xcat-core
    cp -Rp <current location of xcat-dep>/xcat-dep
    

    Option 2:

    If you installed your management node directly from the online repository, you will need to download the xcat-core and xcat-dep tarballs

    • From http://xcat.org/download.html, download the xcat-core and xcat-dep tarball files. Copy these into a subdirectory in the otherpkgdir directory.

      lsdef -t osimage -o rhels7.3-ppc64le-netboot-service -i otherpkgdir
      Object name: rhels7.3-ppc64le-netboot-service
          otherpkgdir=/install/post/otherpkgs/rhels7.3/ppc64le
      
      cd /install/post/otherpkgs/rhels7.3/ppc64le
      mkdir xcat
      cd xcat
      
      # copy the <xcat-core> and <xcat-deb> tarballs here
      
      # extract the tarballs
      tar -jxvf <xcat-core>.tar.bz2
      tar -jxvf <xcat-dep>.tar.bz2
      
  • Run image generation for your osimage definition:

    genimage rhels7.3-ppc64le-netboot-service
    
  • Prevent DHCP from starting up until xcatd has had a chance to configure it:

    export OSIMAGE_ROOT=/install/custom/netboot/rhels7.3-ppc64le-netboot-service/service
    chroot $OSIMAGE_ROOT/rootimg chkconfig dhcpd off
    chroot $OSIMAGE_ROOT/rootimg chkconfig dhcrelay off
    
  • IF using NFS hybrid mode, export /install read-only in Service Node image:

    export OSIMAGE_ROOT=/install/custom/netboot/rhels7.3-ppc64le-netboot-service/service
    cd $OSIMAGE_ROOT/rootimg/etc
    echo '/install *(ro,no_root_squash,sync,fsid=13)' >exports
    
  • Pack the image for your osimage definition:

    packimage rhels7.3-ppc64le-netboot-service
    

Install Service Nodes

rinstall service osimage=rhels7.3-ppc64le-netboot-service

Watch the installation progress using either wcons or rcons and monitor log messages:

wcons service     # make sure DISPLAY is set to your X server/VNC or
rcons <node_name>
tail -f /var/log/messages

Enable localdisk for stateless Service Node (Optional)

If you want, your can leverage local disk to contain some directories during the stateless nodes running. And you can customize the osimage definition to achieve it. For Service Node, it is recommended to put below directories on local disk.

#/install         (Not required when using shared /install directory)
#/tftpboot        (Not required when using shared /tftpboot directory)
/var/log
/tmp

The following section explains how to accomplish this.

  • Change the Service Node osimage definition to enable localdisk
#create a partition file to partition and mount the disk
export OSIMAGE=rhels7.3-ppc64le-netboot-service
cat<<EOF > /install/custom/netboot/$OSIMAGE/partitionfile
enable=yes
enablepart=yes

[disk]
dev=/dev/sda
clear=yes
parts=10,50

[localspace]
dev=/dev/sda2
fstype=ext4

[swapspace]
dev=/dev/sda1
EOF

#add the partition file to Service Node osimage definition and configure ``policy`` table
chdef -t osimage -o $OSIMAGE partitionfile=/install/custom/netboot/$OSIMAGE/partitionfile
chtab priority=7.1 policy.commands=getpartition policy.rule=allow

#define files or directories which are required to be put on local disk
#chtab litefile.image=$OSIMAGE litefile.file=/install/ litefile.options=localdisk
#chtab litefile.image=$OSIMAGE litefile.file=/tftpboot/ litefile.options=localdisk
chtab litefile.image=$OSIMAGE litefile.file=/var/log/ litefile.options=localdisk
chtab litefile.image=$OSIMAGE litefile.file=/tmp/ litefile.options=localdisk
  • Run image generation and repacking for your osimage definition:

    genimage rhels7.3-ppc64le-netboot-service
    packimage rhels7.3-ppc64le-netboot-service
    

Note

enablepart=yes in partition file will partition the local disk at every boot. If you want to preserve the contents on local disk at next boot, change to enablepart=no after the initial provision.

For more information on localdisk option, refer to Enabling the localdisk option

Update Service Node Stateless Image

To update the xCAT software in the image at a later time:

  • Download the updated xcat-core and xcat-dep tarballs from http://xcat.org/download.html and place them in your osimage’s otherpkgdir xcat directory as you did above.
  • Generate and repack the image.
  • Reinstall your Service Node.
genimage "<osimagename>"
packimage "<osimagename>"
rinstall service osimage="<osimagename>"

Note

The Service Nodes are set up as NFS-root servers for the compute nodes. Any time changes are made to any compute image on the mgmt node it will be necessary to sync all changes to all Service Nodes. In our case the /install directory is mounted on the Service Nodes, so the update to the compute node image is automatically available.