[[PageOutline]] = 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 * [[Image(wiki:jazz/DRBL_Xen:drbl_xen_vmx.jpg)]] * VMWare Image without disk as DRBL Client * [[Image(wiki:jazz/DRBL_Xen:drbl_xen_client_vmx.jpg)]] == 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. * [[Image(wiki:jazz/DRBL_Xen:xen_4gb_seg_fixup.png)]] * 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 }}} * [FYI] [http://www.linuxquestions.org/questions/fedora-35/what-is-the-meaning-of-libtls-directory-385934/ Reload this Page what is the meaning of /lib/tls directory?] * 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 * [[Image(wiki:jazz/DRBL_Xen:xen_grub.png)]] == 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 * [[Image(wiki:jazz/DRBL_Xen:drbl_xen_client_boot.jpg)]] == 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 * [[Image(wiki:jazz/DRBL_Xen:drbl_xen_client_boot_2.jpg)]] * [[Image(wiki:jazz/DRBL_Xen:drbl_xen_client_boot_3.jpg)]] == 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'' {{{ #!diff --- /opt/drbl/sbin/drbl-nfs-exports.org 2008-07-28 22:09:43.000000000 +0800 +++ /opt/drbl/sbin/drbl-nfs-exports 2008-07-28 22:10:06.000000000 +0800 @@ -135,6 +135,7 @@ for subnet in $subnet_list; do cat <> $nfs_exports $drbl_common_root $subnet.*($EXPORTS_NFS_RO_NRS_OPT) +/boot $subnet.*($EXPORTS_NFS_RO_NRS_OPT) /usr $subnet.*($EXPORTS_NFS_RO_NRS_OPT) /opt $subnet.*($EXPORTS_NFS_RO_NRS_OPT) /home $subnet.*($EXPORTS_NFS_RW_NRS_OPT) @@ -169,6 +170,7 @@ for ip in `get-client-ip-list`; do cat <> $nfs_exports $drbl_common_root $ip($EXPORTS_NFS_RO_NRS_OPT) +/boot $ip($EXPORTS_NFS_RO_NRS_OPT) /usr $ip($EXPORTS_NFS_RO_NRS_OPT) /opt $ip($EXPORTS_NFS_RO_NRS_OPT) /home $ip($EXPORTS_NFS_RW_NRS_OPT) }}} * step 2: patch ''/opt/drbl/sbin/drbl-gen-client-files'' {{{ #!diff --- /opt/drbl/sbin/drbl-gen-client-files.org 2008-07-28 22:33:31.000000000 +0800 +++ /opt/drbl/sbin/drbl-gen-client-files 2008-07-28 22:34:20.000000000 +0800 @@ -214,6 +214,7 @@ $nfsserver:$drblroot/$ip/etc /etc nfs $FSTAB_NFS_RW_OPT $nfsserver:$drblroot/$ip/var /var nfs $FSTAB_NFS_RW_OPT $nfsserver:$drblroot/$ip/root /root nfs $FSTAB_NFS_RW_OPT +$nfsserver:/boot /tmp/boot nfs $FSTAB_NFS_RO_OPT $nfsserver:/usr /usr nfs $FSTAB_NFS_RO_OPT $nfsserver:/opt /opt nfs $FSTAB_NFS_RO_OPT $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 [http://drbl.sourceforge.net/one4all/ 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 == * According to "[http://fluxcoil.net/doku.php/xen/pxe_booting How-to boot a Xen HVM via PXE]" and "[https://www.cs.tcd.ie/Stephen.Childs/pypxeboot/ pypxeboot]", there are possibilities to boot Xen DomU via PXE. === Case 1: HVM supported === === Case 2: only Para-Virtualization supported === == Reference == * [http://syslinux.zytor.com/wiki/index.php/Xen Syslinux Wiki] * [http://os-drive.com/files/docbook/xen-pxeboot.html Xen PXE Boot Howto] * [http://www.tjd.phlegethon.org/software/ Bootloader support for Xen] * [http://fluxcoil.net/doku.php/xen/pxe_booting How-to boot a Xen HVM via PXE] * [https://www.cs.tcd.ie/Stephen.Childs/pypxeboot/ pypxeboot] * If you are using debian, beware of bug [http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=391152 #391152] * [http://www.possum.in-berlin.de/files/homeserver-20080707.pdf A Time Machine and File Server with RAID, Samba and Xen (PDF)]