wiki:jazz/DRBL_Xen

Massive Deployment of Xen enabled Virtual Cluster using Diskless Remote Boot Linux

Test Environment

  • VMWare Server 1.0.3
  • VMWare Image debian 4.0r1 as DRBL Server
  • VMWare Image without disk as DRBL Client

Pre-installation

  • First, install Xen Hypervisor and Xen enabled Linux Kernel and then reboot
    root@drbl-xen-srv:~# uname -a
    root@drbl-xen-srv:~# mv /lib/tls /lib/tls.disabled
    root@drbl-xen-srv:~# echo "loop max_loop=255" >> /etc/modules
    Linux drbl-xen-srv 2.6.18-6-686 #1 SMP Sat May 24 10:24:42 UTC 2008 i686 GNU/Linux
    root@drbl-xen-srv:~# apt-get install xen-hypervisor-3.0.3-1-i386-pae linux-image-2.6.18-6-xen-vserver-686 xen-tools libc6-xen bridge-utils
    root@drbl-xen-srv:~# update-grub
    root@drbl-xen-srv:~# reboot
    
    • Note1: If you did not install libc6-xen, "4gb seg fixup" error message will keep showing up while booting.
    • Note2: amd64 architecture does not have libc6-xen package (i386 only)
    • Note3: disable tls for libc6-xen
      root@drbl-xeb-srv:/lib# dpkg -S /lib/tls
      libc6-xen, libc6: /lib/tls
      
    • Note4: Xen will use loop device for creating new DomU machine, so we load loop kernel module while booting.
  • Choose Xen to boot at GRUB menu

Install and Configure DRBL

  • Download GPG-KEY-DRBL and add GPG key via apt-key
    root@drbl-xen-srv:~# wget http://drbl.nchc.org.tw/GPG-KEY-DRBL
    root@drbl-xen-srv:~# apt-key add GPG-KEY-DRBL
    
  • Add DRBL repository URL to /etc/apt/sources.list.d/ then install drbl package
    root@drbl-xen-srv:~# echo "deb http://free.nchc.org.tw/drbl-core drbl stable" > /etc/apt/sources.list.d/drbl-sources.list
    root@drbl-xen-srv:~# apt-get update
    root@drbl-xen-srv:~# apt-get install drbl
    
  • Use drblsrv command to setup DRBL server. Here we choose linux-image-2.6.18-6-486 as default DRBL PXE kernel image
    root@drbl-xen-srv:~# /opt/drbl/sbin/drblsrv -i 
    [....skip....]
    Install kernel for clients... ...
    In ayo repository, searching the latest kernel ...
    *****************************************************.
    Now run: /opt/drbl/sbin/drblsrv-offline -c -d -a -l en_US -k /var/cache/apt/archives/linux-image-2.6.18-6-486_2.6.18.dfsg.1-18etch5_i386.deb "" ""
    Kernel package /var/cache/apt/archives/linux-image-2.6.18-6-486_2.6.18.dfsg.1-18etch5_i386.deb is used for client...
    *****************************************************.
    [....skip....]
    
  • Use drblpush command to deploy DRBL Client Image
    root@drbl-xen-srv:~# /opt/drbl/sbin/drblpush -i
    
  • Use Thin Client VMWare Image to test DRBL

Configure PXELinux for Xen Network Booting

  • To load Xen-based kernels you have to use the SYSLINUX multiboot module mboot.c32. So we copy mboot.c32 and Xen hypervisor to TFTP root directory of DRBL.
    root@drbl-xen-srv:~# dpkg -S mboot.c32
    syslinux: /usr/lib/syslinux/mboot.c32
    root@drbl-xen-srv:~# cp /usr/lib/syslinux/mboot.c32 /tftpboot/nbi_img/.
    root@drbl-xen-srv:~# cp /boot/xen-3.0.3-1-i386-pae.gz /tftpboot/nbi_img/.
    
  • Use drblsrv-offline command to generate initial ramdisk of xen-based kernel which is needed for PXE network booting. You should find initrd-pxe.2.6.18-6-xen-vserver-686.img and vmlinuz-2.6.18-6-xen-vserver-686 in /tftpboot/nbi_img/ folder.
    root@drbl-xen-srv:~# /opt/drbl/sbin/drblsrv-offline -s `uname -r`
    root@drbl-xen-srv:~# find /tftpboot/nbi_img/ -name "*-xen*"
    /tftpboot/nbi_img/initrd-pxe.2.6.18-6-xen-vserver-686.img
    /tftpboot/nbi_img/vmlinuz-2.6.18-6-xen-vserver-686
    
    • Note: initrd-pxe.2.6.18-6-xen-vserver-686.img is different from /boot/initrd.img-2.6.18-6-xen-vserver-686. In initrd-pxe.2.6.18-6-xen-vserver-686.img, there are NFS mounting scripts which is needed for each DRBL client.
  • Since Xen-based kernel can not boot with Xen hypervisor, we have to switch vmlinuz-pxe and initrd-pxe.img back to normal linux kernl.
    root@drbl-xen-srv:~# /opt/drbl/sbin/drblsrv-offline -c -d -a -l en_US -k /var/cache/apt/archives/linux-image-2.6.18-6-486_2.6.18.dfsg.1-18etch5_i386.deb
    
    • Note: You can simply remove and recreate the symbolic links named by vmlinuz-pxe and initrd-pxe.img in /tftpboot/nbi_img
      root@drbl-xen-srv:~# cd /tftpboot/nbi_img
      root@drbl-xen-srv:/tftpboot/nbi_img# rm initrd-pxe.img vmlinuz-pxe
      root@drbl-xen-srv:/tftpboot/nbi_img# ln -s initrd-pxe.2.6.18-6-486.img initrd-pxe.img
      root@drbl-xen-srv:/tftpboot/nbi_img# ln -s vmlinuz-2.6.18-6-486 vmlinuz-pxe
      
  • Add a new Xen option to pxelinux.cfg
    root@drbl-xen-srv:~# cat << EOF >> /tftpboot/nbi_img/pxelinux.cfg/default
    > label xen cluster
    >   MENU DEFAULT
    >   # MENU HIDE
    >   MENU LABEL Xen 3.0.1-1-i386-pae
    >   # MENU PASSWD
    >   kernel mboot.c32
    >   append xen-3.0.3-1-i386-pae.gz --- vmlinuz-2.6.18-6-xen-vserver-686 root=/dev/sda1 ro console=tty0 --- initrd-pxe.2.6.18-6-xen-vserver-686.img
    >   TEXT HELP
    >   Run Xen 3.0 in each DRBL Client
    >   ENDTEXT
    > EOF
    
  • Use dcs to switch PXE menu
    drbl-xen-srv:~# /opt/drbl/sbin/dcs more switch-pxe-menu
    
  • Use Thin Client VMWare Image to test DRBL

Enable Xend in default rcX.d

  • You can run /etc/init.d/xend start manually to start xen service for each DRBL clients via drbl-doit command.
    root@drbl-xeb-srv:~# /opt/drbl/bin/drbl-doit /etc/init.d/xend start
    
  • You can check the status of xend by running xm list
    root@drbl-xeb-srv:~# /opt/drbl/bin/drbl-doit /usr/sbin/xm list
    
  • To save your time, we recommand you to add xend to default rcX.d by running update-rc.d xend defaults
    root@drbl-xeb-srv:~# /opt/drbl/bin/drbl-doit /usr/sbin/update-rc.d xend defaults
    

Know Issue of DRBL () with Xen

  • Issue 1: Xen DomU Client will need /boot which in only on DRBL Server
    • Step 1: patch /opt/drbl/sbin/drbl-nfs-exports
      • /opt/drbl/sbin/drbl-nfs-exports

        old new  
        135135        for subnet in $subnet_list; do
        136136          cat <<EOF >> $nfs_exports
        137137$drbl_common_root $subnet.*($EXPORTS_NFS_RO_NRS_OPT)
         138/boot $subnet.*($EXPORTS_NFS_RO_NRS_OPT)
        138139/usr $subnet.*($EXPORTS_NFS_RO_NRS_OPT)
        139140/opt $subnet.*($EXPORTS_NFS_RO_NRS_OPT)
        140141/home $subnet.*($EXPORTS_NFS_RW_NRS_OPT)
         
        169170        for ip in `get-client-ip-list`; do
        170171          cat <<EOF >> $nfs_exports
        171172$drbl_common_root $ip($EXPORTS_NFS_RO_NRS_OPT)
         173/boot $ip($EXPORTS_NFS_RO_NRS_OPT)
        172174/usr $ip($EXPORTS_NFS_RO_NRS_OPT)
        173175/opt $ip($EXPORTS_NFS_RO_NRS_OPT)
        174176/home $ip($EXPORTS_NFS_RW_NRS_OPT)
    • step 2: patch /opt/drbl/sbin/drbl-gen-client-files
      • /opt/drbl/sbin/drbl-gen-client-files

        old new  
        214214$nfsserver:$drblroot/$ip/etc      /etc    nfs     $FSTAB_NFS_RW_OPT
        215215$nfsserver:$drblroot/$ip/var      /var    nfs     $FSTAB_NFS_RW_OPT
        216216$nfsserver:$drblroot/$ip/root     /root   nfs     $FSTAB_NFS_RW_OPT
         217$nfsserver:/boot            /tmp/boot   nfs    $FSTAB_NFS_RO_OPT
        217218$nfsserver:/usr             /usr        nfs    $FSTAB_NFS_RO_OPT
        218219$nfsserver:/opt             /opt        nfs    $FSTAB_NFS_RO_OPT
        219220$nfsserver:/home            /home       nfs    $FSTAB_NFS_RW_OPT
    • Step 3: creat a shell script to mount /boot for each node.
      root@drbl-xeb-srv:~# vi mount_boot
      root@drbl-xeb-srv:~# /opt/drbl/sbin/drbl-cp-host mount_boot /etc/init.d/
      root@drbl-xeb-srv:~# /opt/drbl/sbin/drbl-client-service mount_boot on
      
      • Here is mount_boot
        #! /bin/sh
        set -e
        
        # /etc/init.d/mount_boot: mount /boot for DRBL Client which is Xen enabled.
        
        export PATH="${PATH:+$PATH:}/usr/sbin:/sbin"
        
        case "$1" in
          start)
                mkdir -p /tmp/boot
                echo -n "mounting /boot:"
                mount /boot
                echo "[OK]"
                ;;
          stop)
                echo -n "unmounting /boot:"
                umount /boot
                echo "[OK]"
                ;;
        
          *)
                echo "Usage: /etc/init.d/ssh {start|stop}"
                exit 1
        esac
        
        exit 0
        
      • [Note 1] The "/boot" problem had been fixed by DRBL version 1.9.1-5
      • [Note 2] You can also modify "/opt/drbl/conf/client-append-fstab" for adding new mount point for each nodes. You can check the offical document for more detail.
        If all the clients have their local harddisk, and the partition is formated (For example, /dev/hda1, its filesystem is ext3), then if you want the client to mount /dev/hda1 as /localwork when booting. Therefore you can edit /opt/drbl/conf/client-append-fstab, and its syntax is just like /etc/fstab. In this example, you can make /opt/drbl/conf/client-append-fstab like this:
        /dev/hda1 /localwork ext3 defaults 0 0
        (PS: You do not have to create the directory /tftpboot/node_root/localwork in DRBL server manually, later drblpush will do that for you)
        
    • Step 4: run /opt/drbl/sbin/dcs -> re-deploy or /opt/drbl/sbin/drblpush -c /etc/drbl/drblpush.conf to replace current /etc/exports.

Create Xen DomU configure files

  • Use xen-create-image command to create new DomU image
    root@drbl-xen-srv:~# ssh 192.168.0.2
    root@pc002:~# xen-create-image -dir /home/xen --dist etch --debootstrap --fs reiserfs --accounts --kernel /boot/vmlinuz-2.6.18-6-xen-vserver-686 --initrd /boot/initrd.img-2.6.18-6-xen-vserver-686 --hostname etch1 --dhcp --mirror http://free.nchc.org.tw/debian
    root@pc002:~# xm create etch1.cfg
    root@pc002:~# xm list
    

Xen DomU PXE Booting

Case 1: HVM supported

Case 2: only Para-Virtualization supported

Reference

Last modified 16 years ago Last modified on May 4, 2009, 10:46:39 AM

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