✎ sanboot:gentoo_iscsi - Etherboot/gPXE Wiki

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====== Introduction ======
=====  Scope  =====
This How-To is intended for anyone who wants to install Gentoo Linux on an iSCSI target.
  * What is not covered:
    * Understanding and configuring a network environment
  * What is covered:
    * Connecting to the iSCSI target
    * Installing a generic base system
    * Installing the kernel
    * Installing the bootloader

=====  Credits  =====
The information in this document is based on personal experience and information found on the internet.
The following pages proved to be a great resource of information:

  * http://etherboot.org/wiki/sanboot/ubuntu_iscsi (installing ubuntu on iscsi)

  * http://www.gentoo-wiki.info/ISCSI (examples how to use open-iscsi on gentoo)

  * http://www.mail-archive.com/open-iscsi@googlegroups.com/msg00736.html (a bug that kept me busy for a while)

======  Installation  ======
=====  Connect to your iscsi disk  =====
====  Method 1: use (x)ubuntu boot cd (safest)  ====

(I've only tried this with xubuntu, but other ubuntu versions should work as well.)

This is by far the safest way to install, since you are booting from the live-cd, why not just disconnect all your harddrives to avoid mistakes?

===  Install open-iscsi  ===
<code>
 sudo aptitude install open-iscsi</code>

===  Discover your iscsi target  ===
<code>
 sudo iscsi_discovery <SAN-IP></code>

One of the lines should be your target, for example:
<code>
 Logout of [[sid:|8, target: iqn.1986-03.com.sun:02:86afa64e-9baf-451c-84bb-826ea71300db.gentootest, portal: 10.9.8.250,3260]]: successful</code>

===  Connect to your target  ===
<code>
 sudo iscsiadm -m node -p <SAN-IP> -T iqn.1986-03.com.sun:02:86afa64e-9baf-451c-84bb-826ea71300db.gentootest -l</code>

You should see something simmilar to:
<code>
 Logging in to [[iface:|default, target: iqn.1986-03.com.sun:02:86afa64e-9baf-451c-84bb-826ea71300db.gentootest, portal: 10.9.8.250,3260]]
 Login to [[iface:|default, target: iqn.1986-03.com.sun:02:86afa64e-9baf-451c-84bb-826ea71300db.gentootest, portal: 10.9.8.250,3260]]: successful</code>

====  Method 2: use an existing/working gentoo system  ====

===  Update kernel  ===
Make sure your current kernel supports iscsi:
Roll a new kernel if necessary.

I had trouble when CRC32c was compiled as M so i made it *.

Open-iscsi will not start when iSCSI Initiator over TCP/IP is * so you have to make it M for now.
Open-iscsi will not start when iSCSI Transport Attributes is * so you have to make it M for now.

<code>
 Device Drivers  --->
  SCSI device support  --->
    [[*]] SCSI device support
      <*> SCSI disk support
    [[*]] SCSI low-level drivers  --->
      <M>   iSCSI Initiator over TCP/IP
    SCSI Transports  --->
      {M} iSCSI Transport Attributes
 Cryptographic options  --->
   [[*]] Cryptographic API
     <*> CRC32c CRC algorithm</code>

===  Install open-iscsi  ===
<code>
 emerge sys-block/open-iscsi</code>
===  Start the iscsi service  ===
<code>
 /etc/init.d/iscsid start</code>
If you receive an error here that looks like this:
<code>
 * Checking open-iSCSI configuration ...
 * Loading iSCSI modules ...
 * Loading libiscsi: not found ...                                        [[|!! ]]</code>
then you have to addapt your kernel:
<code>
 <M>   iSCSI Initiator over TCP/IP
 {M}   iSCSI Transport Attributes</code>
It has to be compiled as module!

If you see an error like this:
<code>
 * Checking open-iSCSI configuration ...
 * Loading iSCSI modules ...
 * Loading libiscsi ...                                                   [[|ok ]]
 * Loading scsi_transport_iscsi ...                                       [[|ok ]]
 * Loading iscsi_tcp ...                                                  [[|ok ]]
 * Starting iscsid ...
 * Setting up iSCSI targets ...                                           [[|!! ]]
 iscsiadm: No records found!</code>
Then that's fine, since we don't have any targets yet.

===  Discover your iscsi-target  ===
Find the mac-adres of your network card:
<code>
 ifconfig eth0 | grep HWaddr</code>
You should see something like:
<code>
 eth0      Link encap:Ethernet  HWaddr 00:11:22:33:44:55</code>
Discover the target:
<code>
 iscsiadm -m iface -I iface0 --op=new</code>
You should see:
<code>
 New interface iface0 added</code>
next:
<code>
 iscsiadm -m iface -I iface0 --op=update -n iface.hwaddress -v <MAC-ADDRESS></code>
You should see: 
<code>
 iface0 updated.</code>
next:
<code>
 iscsiadm -m discovery -t st -p <TARGET-IP> -P 1</code>
One of the lines should be your target, for example:
<code>
 Target: iqn.1986-03.com.sun:02:86afa64e-9baf-451c-84bb-826ea71300db.gentootest  
        Portal:	10.9.8.250:3260,1
                Iface Name: iface0</code>

===  Connect to your iscsi-target  ===
<code>
 iscsiadm -m node -T iqn.1986-03.com.sun:02:86afa64e-9baf-451c-84bb-826ea71300db.gentootest -l</code>
You should see something like:
<code>
 Logging	in to [[iface:|iface0, target: iqn.1986-03.com.sun:02:86afa64e-9baf-451c-84bb-826ea71300db.gentootest, portal: 10.9.8.250,3260]]
 Login to [[iface:|iface0, target: iqn.1986-03.com.sun:02:86afa64e-9baf-451c-84bb-826ea71300db.gentootest, portal: 10.9.8.250,3260]]: successful</code>

=====  Chroot into your iscsi-disk  =====
(Make sure you are root from now on)

===  Find out where the disk is attached to  ===
(In this case the "disk" is a file filled with zeroes, so fdisk will complain there is no valid partition table, it does not matter.)
<code>
 fdisk -l</code>

You should see something simillar to:
<code>
 Disk /dev/sda: 4194 MB, 4194304000 bytes
 130 heads, 62 sectors/track, 1016 cylinders
 Units = cylinders of 8060 * 512 = 4126720 bytes
 Disk identifier: 0x00000000</code>
 
<code>
 Disk /dev/sda doesn't contain a valid partition table</code>

**WARNING: Pay attention to what device your iscsi disk is attached, if you don't have other disks connected to your computer the device will probably be /dev/sda, if you do have other disks you have to find out what device your iscsi disk is connected to! You don't want to (re)format the wrong disk! I will refer to the disk as /dev/sdX.**

===  Partition the iscsi-harddisk  ===
(i've made only 1 partition to make it simple, you could add boot and swap if you want)
<code>
 fdisk /dev/sdX</code>

===  Format the partition  ===
**Warning: read the bold warning in paragraph "Find out where the disk is attached to"**
<code>
 mke2fs -j /dev/sdX1</code>

===  Make a directory for your chroot environment  ===
<code>
 mkdir /mnt/gentoo</code>

===  Mount your iscsi-disk  ===
<code>
 mount /dev/sdX1 /mnt/gentoo</code>

=====  Install Gentoo Base-system  =====
From here on you have to download a stage3 just like you would in a normal installation. Unpack the stage in /mnt/gentoo.

===  Mount other filesystems  ===
<code>
 mount -t proc none /mnt/gentoo/proc
 mount -o bind /dev /mnt/gentoo/dev</code>

===  Copy resolver config  ===
<code>
 cp -L /etc/resolv.conf /mnt/gentoo/etc/</code>

====  Set timezone  ====
<code>
 cp /usr/share/zoneinfo/Europe/Brussels /etc/localtime</code>
====  Set hostname  ====
<code>
 nano -w /etc/conf.d/hostname</code>

====  Edit config files  ====
<code>
 nano -w /etc/conf.d/clock
 nano -w /etc/rc.conf
 nano -w /etc/conf.d/rc
 nano -w /etc/conf.d/keymaps</code>

====  Install system tools  ====
<code>
 emerge app-admin/syslog-ng sys-process/vixie-cron
 rc-update add syslog-ng default ; rc-update add vixie-cron default</code>

====  Set a root password  ====
<code>
 passwd</code>

====  Network configuration  ====
**IMPORTANT:** Since your storage is connected over the network do not allow init scripts to start or restart the network!

<code>
 nano -w /etc/conf.d/net</code>

<code>
 config_eth0=( "noop" )</code>

====  Fstab  ====
Add your harddisk in fstab like any normal harddisk:
<code>
 nano -w /etc/fstab</code>

<code>
 /dev/sda1               /               ext3            noatime         0 1</code>

=====  Kernel configuration  =====
====  Install the gentoo-sources  ====
<code>
 emerge sys-kernel/gentoo-sources</code>

====  Install genkernel  ====
You need at least version 3.4.10.907 of genkernel so you may have to unmask it first
<code>
 ACCEPT_KEYWORDS="~yourach" emerge sys-kernel/genkernel</code>

====  Compile the sources with genkernel  ====
Dont forget to add --iscsi for iscsi support.
<code>
 genkernel --menuconfig --iscsi all</code>

===  Enable (i)scsi  ===
I had trouble when CRC32c was compiled as M so i made it *.

Now iSCSI Initiator over TCP/IP has to be * not M!
Now iSCSI Transport Attributes has to be * not M!

<code>
 Device Drivers  --->
  SCSI device support  --->
    [[*]] SCSI device support
      <*> SCSI disk support
    [[*]] SCSI low-level drivers  --->
      <*>   iSCSI Initiator over TCP/IP
    SCSI Transports  --->
      {*} iSCSI Transport Attributes
 Cryptographic options  --->
   [[*]] Cryptographic API
     <*> CRC32c CRC algorithm</code>

===  Enable networking  ===
<code>
 Networking support  --->
    Networking options --->
      <*> Packet socket
      <*> Unix domain sockets
      [[*]] TCP/IP networking
      [[*]]   IP: multicasting
      [[*]]   IP: kernel level autoconfiguration
      [[*]]     IP: DHCP support</code>

===  Enable your network card  ===
Enable your network card as BUILT IN [[*]], not module!!
<code>
 Device Drivers  --->
   [[*]] Network device support  --->
   [[?]]   Ethernet (10 or 100Mbit)  --->
   [[?]]   Ethernet (1000 Mbit)  --->
   [[?]]   Ethernet (10000 Mbit)  ---></code>

=====  Install Bootloader  =====
==== Install grub  ====
<code>
 emerge sys-boot/grub</code>

====  Configure Grub  ====
<code>
 grub</code>

**WARNING, WARNING, WARNING: make sure you enter the right disk!! if you are running the ubuntu-cd and don't have any real harddisks connected to your computer then hdx=hd0, if you are installing from a real harddisk then hdX=hd1 or hd2 or so on!!!
**
<code>
 root (hdX,0)
 setup (hdX)
 quit</code>

====  Edit grub configuration  ====
You have to set at least these options for iscsi to work:
ip=dhcp, iscsi_target=, iscsi_address=, iscsi_initiatorname ======

<code>
 nano -w /boot/grub/grub.conf</code>

<code>
 default 0
 timeout 10</code>
 
<code>
 title Gentoo Linux 2.6.31-r6 iSCSI
 root (hd0,0)
 kernel /boot/kernel-genkernel-x86_64-2.6.31-gentoo-r6 ip=dhcp root=/dev/ram0 init=/linuxrc ramdisk=8192 real_root=/dev/sda1 iscsi_target=iqn.1986-03.com.sun:02:86afa64e-9baf-451c-84bb-826ea71300db.gentootest iscsi_address=10.9.8.250 iscsi_initiatorname=iqn.1993-08.org.gentooclient5:01:22b2ed5d3ccc
 initrd /boot/initramfs-genkernel-x86_64-2.6.31-gentoo-r6</code>

=====  Leave chroot  =====
<code>
 cd ~
 exit</code>
If you dont' have a boot partition like me then you can leave out /mnt/gentoo/boot
<code>
 umount /mnt/gentoo/dev /mnt/gentoo/proc /mnt/gentoo/boot /mnt/gentoo</code>

======  Troubeshooting  ======
=====  Made a mistake in the base system  =====
You can connect to your iscsi disk again with one of the methods above, chroot and fix the problem.
=====  System won't boot and drops you in a shell  =====
Enter the shell and try to figure out what went wrong.
  * Did the network interface come up with an ip-adres?
<code>
 ifconfig eth0</code>

You may have forgotten to enable the kernel ip autoconfiguration and the kernel dhcp

You may have forgotten to enable your network card in the kernel (* not M)

  * Does dmesg show any warnings?
<code>
 dmesg</code>

If demsg complains about crc32 you probably compiled it as M not *.

  * Can you connect to the target manually?
<code>
 iscsistart --help</code>
=====  Gentoo boots partially but then complains about a read-only filesystem  =====
You probably didn't edit /etc/fstab right
<code>
 mount -o remount rw /
 nano -w /etc/fstab
 sync
 reboot</code>
=====  Kernel boots but hangs/crashes when it tries to bring up eth0  =====
You cannot allow the system to start or restart the network connection, this will severa your iscsi connection!
<code>
 mount  -o remount rw /
 nano -w /etc/conf.d/net</code>

<code>
 config_eth0=( "noop" )</code>

<code>
 sync
 reboot</code>

=====  Boot fails when adding other storage to computer  =====
If you add a harddisk, usb drive, usb-stick to the computer it will probably take the /dev/sda spot and your iscsi-disk will move to /dev/sdb or, /dev/sdc, or so on...

======  FIXME  ======
Gentoo will not shut down properly.
Trace: • socideas • winvista • iscsiboot • gentoo_iscsi • debian_lenny_iscsi • tg3
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