✎ soc:2009:pravin:journal:bkodebianiscsi

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====== Booting debian over iscsi ======
Here I will be documenting my first attempt to boot linux over iscsi.

===== Reason to choose debian =====
  - Chose debian because the squashfs of debian works fine and there are no other problems.
  - Also, all the kernel modules needed for iscsi initiator are inside initramfs so, less work for me. :-)
  - No considerable success yet :-(

===== Installing the target =====
The target for these experiments is installed on my laptop (Ubuntu-9.04) with following procedure.
Most of these steps are taken from blog [[http://www.howtoforge.com/using-iscsi-on-ubuntu-9.04-initiator-and-target|Using iscsi over ubuntu 9.04]]\\

Installing iscsi target
<code>
sudo apt-get install iscsitarget
</code>

Configure the target by editing ''/etc/default/iscsitarget'', ''/etc/ietd.conf'' and ''/etc/initiators.allow'' files as follows\\

  - Open ''/etc/default/iscsitarget'' and set ''ISCSITARGET_ENABLE=true''
  - Open ''/etc/ietd.conf'', and comment out all lines, then add following paragraph
<code>
Target iqn.2001-04.com.example:storage.lun1
        IncomingUser 
        OutgoingUser
        Lun 0 Path=/var/www/debian-live-501-i386-gnome-desktop.iso,Type=fileio,IOMode=ro
        Alias LUN1
</code>

Now we add following line to "/etc/initiators.allow"
<code>  
ALL ALL
</code>
This should allow any initiator to access any lun device\\
and then, restart the target
<code>
sudo /etc/init.d/iscsitarget restart
</code>

===== Testing the target =====
The iscsi target is tested by installing iscsi initiator on same laptop.  Following is the procedure.\\

  * Installing
<code>
sudo apt-get install open-iscsi
</code>
  
  * configure iscsi initiator to start nodes automatically\\
Edit the file ''/etc/iscsi/iscsid.conf'' to have line ''node.startup = automatic''
  
  * and then restart the initiator
<code>
/etc/init.d/open-iscsi restart
</code>

  * Now, do the discovery of nodes available
<code>
$ sudo iscsiadm -m discovery -t st -p 192.168.0.1
192.168.0.1:3260,1 iqn.2001-04.com.example:storage.lun1
</code>
  * I dont know why this command is needed, but it was in the blog, so I am adding it here
<code>
$ sudo iscsiadm -m node
192.168.0.1:3260,1 iqn.2001-04.com.example:storage.lun1
</code>
  * Logging in
<code>
$ sudo iscsiadm -m node --targetname "iqn.2001-04.com.example:storage.lun1" --portal "192.168.0.1:3260" --login
Logging in to [iface: default, target: iqn.2001-04.com.example:storage.lun1, portal: 192.168.0.1,3260]
Login to [iface: default, target: iqn.2001-04.com.example:storage.lun1, portal: 192.168.0.1,3260]: successful
</code>

  * and it is done, you can see the new device with ''fdisk -l'' command
<code>
$ sudo fdisk -l
[sudo] password for pravin: 

Disk /dev/sda: 250.0 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0xa9f9aa9b

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1           5       40131   de  Dell Utility
[...]
[...]
[...]

Disk /dev/sdc: 724 MB, 724785152 bytes
23 heads, 61 sectors/track, 1008 cylinders
Units = cylinders of 1403 * 512 = 718336 bytes
Disk identifier: 0x00000000

Disk /dev/sdc doesn't contain a valid partition table

$ sudo mount -t iso9660 /dev/sdc mpoint
mount: block device /dev/sdc is write-protected, mounting read-only

$ mount
/dev/sda6 on / type ext3 (rw,relatime,errors=remount-ro)
[...]
[...]
[...]
/dev/sdc on /home/pravin/Etherboot/git/BKO.git/pxeknife/debian/debian-live-501-i386/mpoint type iso9660 (ro) 

$ ls mpoint
doc  isolinux  live  md5sum.txt
</code>

As Now I know that my target is working correctly, I am free to try out booting from this target 8-)

===== Configuring initramfs as initiator =====
I need to add all the tools, configuration files and kernel modules to initramfs so that I can use them from there to connect.

  * ** Step 1 **, __Kernel Modules__ : on checking the contents of ''/etc/init.d/open-iscsi'' it seems that following kernel modules are to be inserted
<code>
modprobe iscsi_tcp
modprobe ib_iser 
</code>
  * These modules are already in debian initramfs, so no need to worry about that :)

  * ** Step 2 ** __Tools needed__ : Again ''/etc/init.d/open-iscsi'' tells us that it uses ''/sbin/iscsid'' and ''/sbin/iscsiadm''\\
but there are more iscsi related tools in /sbin
<code>
$ ls /sbin/iscsi*
/sbin/iscsiadm  /sbin/iscsid  /sbin/iscsi_discovery  /sbin/iscsi-iname  /sbin/iscsistart
</code>
To avoid any missing dependencies, better to add all above tools to initramfs.

  * ** Step 3 ** __Configuration Files__ : From man page of iscsiadm and iscsid, we can guess that following configuration files will be needed
<code>
/etc/iscsi/iscsid.conf
/etc/iscsi/initiatorname.iscsi
</code>

===== Testing new initramfs =====
The HTTPFS code has been commented out so that initramfs will give me rescue shell, which can be used to start the iscsi initiator.\\
Following commands were executed once the rescue shell is provided.
<code>
modprobe iscsi_tcp
modprobe ib_iser
mkdir /var/run
/sbin/iscsid
iscsiadm -m discovery -t st -p 192.168.0.1
</code>
and no node is shown :(\\
I tried to run iscsid in debug mode with following command
<code>
/sbin/iscsid -d 8 -f
iscsid : sysfs_init: sysfs_path='/sys'
[...]
[...]

iscsid: reaped pid 994, reap_count now 0
</code>
and also ran ''iscsiadm'' in debug mode with following output
<code>
(initramfs) iscsiadm -d 8 -m discovery -t st -p 192.168.0.1
iscsiadm: ip 192.168.0.1, port 3260, tgpt -1
iscsiadm: Max file limits 1024 1024
</code>
This output is definately very less compuare to the output of same command executed on my laptop.
Trace: • winbootibft • staging • bkostaticip • ubuntu_iscsi2 • pxekniferomomatic • bkodebianiscsi • dslbko • httpfsprobs
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