Edição das 10h40min de 27 de outubro de 2010

Diskless Remote Boot in Linux (DRBL)

Preamble

Este documento descreve como setup o ambiente "DRBL" em (para outros sistemas veja o original):

• Fedora Core 13

Setup the Diskless Remote boot in Linux (DRBL) Environment

I. Configuração do Servidor Linux

• Instale o Linux e configure todas as placas de rede. Neste texto, usamos eth0 para conectar a internet, enquanto que eth1, eth2, eth3 são para o DRBL (coloque o IP das placas de rede como IP privado (i.e. 192.168.x.x, no exemplo: eth1:192.168.101.254, eth2:192.168.102.254, eth3:192.168.103.254...)); IPs privados (e.g. 192.168.x.x) são usados para o ambiente DRBL. Se no seu Linux o serviço NetworkManager é iniciado automaticamente, é recomendado desligar ou remover. No Fedora você pode: chkconfig --del NetworkManager, chkconfig --del NetworkManagerDispatcher, e ligar o serviço de rede com "chkconfig network on". Suas regras para o firewall serão reescritas no servidor DRBL. Depois de completar o setup do DRBL e testar com sucesso, você pode reconfigurar o firewall. Lembre que os serviços NIS, tftp e dhcp são necessários, assim NÃO bloqueie eles no firewall.

• Para melhor performance (opcional):
  • Se você usa o Gnome, pode apagar alguns arquivos de linguagem em /etc/gconf/gconf.xml.defaults/. Isto economiza espaço no servidor (Ex.: mantendo somente %gconf-tree.xml e %gconf-tree-zh_TW.xml economizará 40 MB (Com 16 clientes economizará 640 MB no servidor) e o carregamento no servidor NFS será menor.
  • O sistema de arquivos reiserfs é recomendado (se disponível) por melhor performance (comparado com ext2/ext3).

• Depois de instalar o Linux no servidor, tenha certeza que o modo DMA está ativo. Isto acelera a velocidade de acesso ao disco do servidor. Use hdparm /dev/hdx para verificar se o modo está ativo ou não. Se estiver off, rode hdparm -d1 -c3 -k1 /dev/hdx para ativar. Troque /dev/hdx por /dev/hda se seu disco IDE para o sistema Linux está em "Primary IDE".

• Nota sobre Selinux: Desligue ao menos que entenda como usá-lo (senão poderá ter "Permission denied"). Para desabilitar SELinux, digite SELINUX=disabled em /etc/sysconfig/selinux or /etc/selinux/config e reinicialize sua máquina.

II. Configuração dos clientes

Nota: Este processo é feito no servidor para uso nos clientes.

Passo 2a

• Instale a DRBL key (ID: 1024D/D7E8DF3A, Key fingerprint = F532 A131 65AF 2168 1634 DB1B 4000 9511 D7E8 DF3A) no seu sistema rpm. Três modos de fazer isso:

   rm -f GPG-KEY-DRBL; wget http://drbl.org/GPG-KEY-DRBL; rpm --import GPG-KEY-DRBL
 ou
   rm -f GPG-KEY-DRBL; wget http://drbl.nchc.org.tw/GPG-KEY-DRBL; rpm --import GPG-KEY-DRBL
 ou  baixe a key do key server. O KeyID para DRBL é D7E8DF3A:
   gpg --keyserver subkeys.pgp.net --recv-key D7E8DF3A

e rode (para adicionar ao sistema rpm)

   gpg -a --export D7E8DF3A > GPG-KEY-DRBL; rpm --import GPG-KEY-DRBL

• Baixe o arquivo drbl-1.9.6-35.i386.rpm (por exemplo, a versão estável está no Sourceforge)
• Se conecte como root su - root
• Instale o arquivo que você baixou:

   yum install drbl-XXX.i386.rpm
    ou
   rpm -Uvh drbl-XXX.i386.rpm

• Nota: Um módulo perl é necessário (Algo como "perl-Digest-SHA1"). Usando yum baixará automaticamente, senão use

  yum install perl-Digest-SHA1

Se usar rpm, instale com (Fedora 8)

  rpm -Uvh http://opensource.nchc.org.tw/fedora/linux/releases/8/Fedora/i386/os/Packages/perl-Digest-SHA1-2.11-4.fc8.i386.rpm

PS. Os arquivos DRBL estão em http://ftp.twaren.net/local-distfiles/drbl-core/ ou http://free.nchc.org.tw/drbl-core

Passo 2b

• Cenário 1 - Internet rápida (Pressione Enter para aceitar a opção default),

 /opt/drbl/sbin/drblsrv -i

• Cenário 2 - Sem internet ou internet lenta: Instale os pacotes com

 /opt/drbl/sbin/drblsrv-offline

Os pacotes necessários pode ser listados com "/opt/drbl/sbin/drblsrv-offline -r". After you install those required packages, if you are sure the kernel in the server meets the client's CPU arch, you can run "/opt/drbl/sbin/drblsrv-offline -s `uname -r`", or you can download appropriate kernel rpm/deb file, which meets the client's CPU arch. Then run "/opt/drbl/sbin/drblsrv-offline -k $KERNEL_PKG" (Replace $KERNEL_PKG with the downloaded kernel rpm or deb file name with path). If you are uncertain, just press Enter to accept the default value when you run drblsrv-offline. (PS 1. More options for drblsrv-offline can be shown by "/opt/drbl/sbin/drblsrv-offline --help". PS 2. To install DRBL in Scientific Linux 5.0, you can refer to this FAQ)

• For the impatient: If you are impatient, your network bandwidth to Internet is good, and your GNU/Linux distribution provides apt, urpmi or yum repository, you can run "/opt/drbl/sbin/drbl4imp" to finish step "2b" and "3a". "drbl4imp" uses the default values to setup the DRBL server. THIS IS VERY IMPORTANT! The default value might not fit your environment! It uses the "range" option in dhcp server so your DRBL client will not always get the same IP address. It also assumes each of the server's network card (except eth0) provides DRBL services to 12 clients. If you want the setup to fit your environment, please run steps "2b" and "3a" step-by-step.

III. Set up the file system for the client in the Server

• Arrange your environment and make sure you know it.
• Taking NCHC's computer class room C as an example: There are 40 computers. In order to get DRBL to work more efficiently, we separated them to 4 subnets: 192.168.100.0, 192.168.101.0, 192.168.102.0 and 192.168.103.0. There are four Ethernet cards in DRBL server. One is for WAN and the others are for LAN. The IPs of DRBL environment (LAN) are 192.168.100.254, 192.168.101.254, 192.168.102.254 and 192.168.3.254. The services DHCP, TFTP, NFS, etc will run on eth0:1, eth1, eth2, and eth3.

              NIC    NIC IP                    Clients
     +-----------------------------+
     |         DRBL SERVER         |
     |                             |
     |+-- [eth0] public IP         +- to WAN
     |     (ex. 61.216.116.23)     |
     |                             |
     |+-- [eth0:1] 192.168.100.254 +- to clients group 1 [ 10 clients, their IP
     |                             |            from 192.168.100.1 - 192.168.100.10]
     |+-- [eth1] 192.168.101.254   +- to clients group 1 [ 10 clients, their IP
     |                             |            from 192.168.101.1 - 192.168.101.10]
     |+-- [eth2] 192.168.102.254   +- to clients group 2 [ 10 clients, their IP
     |                             |            from 192.168.102.1 - 192.168.102.10]
     |+-- [eth3] 192.168.103.254   +- to clients group 3 [ 10 clients, their IP
     |                             |            from 192.168.103.1 - 192.168.103.10]
     +-----------------------------+

   * There are four modes available from DRBL version 1.6.3 or later: Full DRBL, Full Clonezilla, DRBL SSI (Single System Image) and Clonezilla Box. The network bandwidth and disk space requirement are higher in the former two modes, but all the system setting will be saved to server's disk, and every client can have its own individual setting. On the other hand, the DRBL SSI uses single system image for all clients, and the necessary individual settings of clients are created run-time when they boot. This will reduce the required disk space in the server since only one image is necessary. However, the disadvantage is every client can NOT have its own individual system setting (Users' setting will be saved to server). In DRBL SSI mode, once there are extra client nodes want to join DRBL environment, all you have to do is modify the dhcpd config file (dhcpd.conf), then use "/opt/drbl/sbin/dcs -> others -> gen_3N_conf" to create or run "/opt/drbl/sbin/drbl-3n-conf generate", the necessary files will be created. In this mode, theoretically one network card in the server can provide 253 clients. The fourth mode, Clonezilla box mode, is based on DRBL SSI mode, especially for clone system. If you want to use DRBL SSI mode, make sure your client has large memory (say > 512 MB), and all the hardware (especially the graphic card) in the clients are the same. Check this comparison table for these four modes.

   * Notes for network switch and NICs when using multiple NICs:

     When you use multiple NICs to expand the bandwidth, we recommend you set the MAC addresses so that every node will get the same IP address all the time. (i.e. in the following step 3a, when you run "/opt/drbl/sbin/drblpush -i", it prompts "Do you want to fix the IP address of client connected to eth1 by giving MAC address ? [y/N]", choose "Y"). If you do NOT set MAC address (we will call it "range" from now), and you have only one 48-port network switch (or many switches but connected to be one), and you use four NICs (or more than two...) in DRBL server to expand the network bandwidth, a problem will occur (i.e. some clients will not lease IP from DHCP server) so it will not be able to boot.
     On the other hand, if your DRBL server uses four NICs to expand the network bandwidth (meaning that four NICs with four private subnets such as 192.168.100.x, 192.168,101,x, 192.168.102.x, 192.168.103.x), and you have exactly four switches that are separated and not connected to each other, then you can use range (i.e. you do not have to set the MAC address of clients).
     Remember, if you use N NICs to expand network bandwidth in the DRBL server, if using the "range" method, then you must have N switches and they can NOT be connected to each other.
   * Before executing step <3a>, you can do some customized config:
        1. If you have some specific directories in this DRBL server to share, such as /work1, then you can use text editor to open file /opt/drbl/conf/drbl.conf, edit the diskless_root_dir_ro_user_add="/work1"(If you want /work1 can only be read by clients, not writable), or diskless_root_dir_rw_user_add="/work1"(If you want /work1 to be readable and writable by clients. (Warning!!! drbl.conf is VERY IMPORTANT, be careful when you edit it!!!)
        2. 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)
        3. If you have extra services (such as apmd and bluetooth) to be on when client boots, you can edit /opt/drbl/conf/client-extra-service, let service_extra_added="apmd bluetooth".
        4. If you want to overwrite some or all automatically created hostnames later by "drblpush -i", you can edit "/opt/drbl/conf/client-ip-hostname" now. Check that file for the format. If some machines are not assigned, drblpush will use those automatically created hostname. 

   * <Step 3a> run "/opt/drbl/sbin/drblpush -i". The software will auto-detect the system to figure out the argument. If the argument is not set up in the system, the system will request you to do that. Example: see here.

   * Note!!! If newer packages are installed in the server after this step, you have to run "/opt/drbl/sbin/drblpush -i" or "/opt/drbl/sbin/drblpush -c /etc/drbl/drblpush.conf" (This will loaded the previously saved settings) again so that newer packages will be deployed to clients.
   * Note!!! It is not recommended to turn on the system update automatically. Since If newer packages are installed in the server automatically, without running "/opt/drbl/sbin/drblpush -i", the programs for client might not be compatible with that newer in server. If you want to turn on system update automatically, remember to follow the above step to update the files in client automatically.

IV. Setting up clients to use the DRBL environment

         o There are four different scenarios where you can make clients boot from network: 1) the client has PXE network interface card, 2) the client has a floppy drive, 3) the client has a CDROM, 4) the client has a local hard drive. We use etherboot 5.4.3 as an example for cases 2-4. NOTE! With DRBL version 1.3.9 or later, if you want to use Etherboot, Etherboot bersion 5.4.0 or newer is required.

         o Case 1: The client has a PXE network interface card
               + Set the client's BIOS to boot from "LAN" or "network".
               + Take one of the Asus motherboards for example, in this manual file.
                    1. Page 4-24, you will see OnBoard LAN, there is a subfuncton "OnBoard LAN BOOT ROM", normally it's disabled, you have to enable it.
                    2. Usually you have to reboot it now, make the function re-read by BIOS.
                    3. After rebooting, enter BIOS setting again, this time, in Page 4-35, you have to make LAN boot as the 1st boot device.
               + That's it. Let client boot and enjoy DRBL!!!

         o Case 2: The client has a floppy drive.
               + <Step 4a> Get the image file first.
                     # Use the "universal" image /opt/drbl-etherboot/etherboot-net.zdsk in the DRBL server. It supports most modern network cards. (Ref: here. If this universal image fails, try using specific image for client's network card, the image file is located in /opt/drbl-etherboot/. As an example, if you have a Realtek 8139 network card, use the image /opt/drbl-etherboot/rtl8139.zdsk.
               + <Step 4b> Insert the floppy to floppy drive in DRBL server
                     # Run "cat /opt/drbl-etherboot/etherboot-net.zdsk > /dev/fd0" in the DRBL server.
                     # If you want to create the image floppy in M$ windows, download rawrite.exe or "RawWrite for windows" (http://uranus.it.swin.edu.au/~jn/linux/) to write the ROM image to floppy.
               + <Step 4c> Put this floppy to client's floppy drive, make sure the floppy is the first boot device in the client's BIOS. If everything was done correctly, after a few minutes, the clients will be waiting for you to login, All the accounts are same as the ones in server.

         o Case 3: Client has a CDROM (Reference):
               + 1) The "universal" image is located in /opt/drbl-etherboot/etherboot-net.iso
                 2) Burn the ISO to a CD:
                 cdrecord -v speed=12 fs=16m dev=0,0,0 -data etherboot-net.iso
                 (If necessary, modify "dev=0,0,0", run "cdrecord -scanbus" to get your CD burner.)
                 3) Ensure the PC is set to boot from CDROM, place the burned CD in the drive, and reboot. Done!

         o Case 4: client has a local hard drive
               + If the client has a local hard drive which is installed with the bootloader grub in GNU/Linux:
                 1. Copy the file "/opt/drbl-etherboot/etherboot-net.zlilo" to client's directory "/boot/" in its harddisk
                 2. Append one block in the client's /boot/grub/menu.lst or /boot/grub/grub.conf (depends on your distribution) like this:
                 ---------------
                 title Etherboot-PXE
                 kernel /boot/etherboot-net.zlilo
                 ---------------
                 3. Change the default boot to the corresponding one above, like "default 1", in menu.lst or grub.conf in client.
               + If the client is running M$ Windows XP/2K on its hard disk:
                 You can install WINGRUB. Put the file etherboot-net.zlilo in C:\, and the files: C:\boot.ini and C:\GRUB\MENU.LST look like: (This method is only suitable for installing wingrub in BOOT.INI (Tool -> Install grub -> Boot from BOOT.INI). If necessary, you can use other modes provides by WinGRUB):
                 boot.ini:
                 ---------------
                 [boot loader]
                 timeout=30
                 default=C:\GRLDR
                 [operating systems]
                 multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect
                 C:\GRLDR="Etherboot"
                 ---------------
                 MENU.LST:
                 ---------------
                 timeout 7

                 title etherboot
                 root (hd0,0)
                 kernel /etherboot-net.zlilo

                 title Windows at (hd0,0)
                 root (hd0,0)
                 chainloader +1
                 ---------------
               + If the client has local hard drive which is installed with M$ Windows 9x:
                 1. Copy the file "/opt/drbl-etherboot/etherboot-net.com" to client's hard disk
                 2. Rename it so that it is shorter in client, for example, "eb-net.com".
                 3. Write a multi-boot config file in the client (e.g. add one paragraph to run "eb-net.com").

V. Additional usage for the DRBL environment

         o Some useful scripts are located in the directories /opt/drbl/sbin and /opt/drbl/bin in the server, Take a look at them. Usage will appear by running them without parameters.
         o The most useful command is /opt/drbl/sbin/dcs which sets the client's default boot mode. Here's a screenshot of what it looks like:

           drbl_client_switch screenshot

         o Another useful command is drbl-SL.sh, it can load Small GNU/Linux (DSL, PuppyLinux, INSERT, PLD, Debian Live, GeeXbox, PUD-Linux...) into DRBL environment. By doing this, the client can use that Small GNU/Linu after booting via PXE. The client still can work even if the network cable is unplugged. It's fire and forget. For more info, check here.

6. Upgrade

Para upgrade para uma versão mais nova:

1. Backup the important files, such as those files in /etc/drbl and /etc/dhcpd.conf or /etc/dhcp3/dhcpd.conf, etc...
2. Run "/opt/drbl/sbin/drblsrv -u" to uninstall all the DRBL-related packages
3. Follow the step II, download the drbl main program, re-install and configure it again (i.e. /opt/drbl/sbin/drblsrv -i and /opt/drbl/sbin/drblpush -i)

Algumas vezes, se as versões são próximas, podes tentar upgrade sem reinstalar e reconfigurar (i.e. somente yum upgrade). Entretanto, não é recomendado, pois alguns arquivos serão enviados aos clientes somente depois que drblsrv e drblpush são rodados.

7. Uninstall

Para desinstalar drbl e pacotes relacionados, rode:

/opt/drbl/sbin/drblsrv -u

e siga os passos.

References

• <a href="http://drbl.nchc.org.tw">http;//drbl.nchc.org.tw</a>
• <a href="http://drbl.sf.net">http://drbl.sf.net</a>
  
• <a href="http://free.nchc.org.tw">http://free.nchc.org.tw</a>
• <a href="http://www.study-area.org/">http://www.study-area.org/</a>
• <a href="http://etherboot.sourceforge.org/">http://etherboot.sourceforge.org/</a>
• <a href="http://www.rom-o-matic.net/">http://www.rom-o-matic.net/</a>
• <a href="http://www.ltsp.org/">http://www.ltsp.org/</a>
• <a href="http://www.tldp.org/HOWTO/Diskless-HOWTO.html">Diskless HOWTO</a>
• <a href="http://www.tldp.org/HOWTO/Diskless-root-NFS-HOWTO.html">Diskless-nfs-root HOWTO</a>
• <a href="http://www.tldp.org/HOWTO/Diskless-root-NFS-other-HOWTO.html">Diskless-nfs-root-other HOWTO</a>
• <a href="http://www.tldp.org/HOWTO/Network-boot-HOWTO/index.html" target="_top">Network-boot-HOWTO</a>
  
• <a href="http://www.tldp.org/HOWTO/NIS-HOWTO/index.html">NIS HOWTO</a>
• <a href="http://www.tldp.org/HOWTO/NFS-HOWTO/index.html">NFS HOWTO</a>
• <a href="./etherboot_doc">Etherboot User Manual</a>
• <a href="http://disklessworkstations.com/">http://disklessworkstations.com/</a>
• <a href="http://www.ltsp.org/documentation/eproms.txt">How to pick a bootrom</a>
• <a href="http://diet-pc.sourceforge.net/">DIET-PC</a>