[ipxe-devel] trouble booting CentOS from Netapp iSCSI LUN

Scott Classen sclassen at lbl.gov
Fri Mar 4 06:09:46 UTC 2011


On Mar 3, 2011, at 3:22 AM, Michael Brown wrote:

> On Thursday 03 Mar 2011 05:12:45 Scott Classen wrote:
>>> That is the current default, if no explicit initiator IQN is specified
>>> via either DHCP option 203 or the "initiator-iqn" setting.
>> What is DHCP option 203? Can I add another line to my dhcpd.conf file to
>> specify the iqn of my client?… like this:
>> <snip>
> Yes.  Buried in the middle of http://ipxe.org/howto/dhcpd, you'll find a line
>  option iscsi-initiator-iqn code 203 = string;
> You can use this as follows:
>  option iscsi-initiator-iqn code 203 = string;
>  host samos {
>    ...
>    option iscsi-initiator-iqn “iqn.2010-2011.com.mycustominitiator";
>    .,.
>  }

Yes, indeed. This works well. Now when iPXE first contacts the NetApp it identifies itself with the proper initiator.

>> I performed a GUI-based installation and in the advanced partitioning
>> section connected to the netapp, loaded the iSCSI LUNs and installed the
>> root filesystem onto the NetApp LUN. The installation proceeded as
>> expected and then I was prompted to reboot. Of course this is where I have
>> run into problems, but I think I’m making some good progress. At least
>> iPXE can successfully connect to the NetApp I just need to figure out why
>> the boot process freezes.
>> I think I might go through the CentOS install again and double check that
>> /boot is also being installed on the iSCSI LUN.
> Also potentially worth connecting to the LUN from another Linux system and 
> verifying that /sbin/fdisk gives sensible output (including a partition marked 
> as "active"), and that a bootloader (e.g. grub or lilo) is installed on the 
> disk.
> Michael

Thank you so much for your nudges in the right direction. Turns out that I had not installed grub on the proper partition. It’s a rather long and convoluted story, but essentially I re-installed CentOS (via a regular PXE boot along with a network accessible kickstart file). I carefully made sure to install grub and the mbr onto the /boot partition of the iSCSI LUN. It took a few more reboots to figure out that I also needed to be very specific about the LUN number in the DHCP iscsi root-path statement. Even though the NetApp filer is set up to map a single LUN to a single initiator I still had to specify the LUN to get a successful boot. like this:

option root-path "iscsi:

Now it just works! yeah!

I had to do some jiggery pokery in the dhcpd.conf file (commenting out the iPXE chainloading stuff) so that I could boot my regular PXE menu for the initial installation. I then had to uncomment the iPXE stuff, restart dhcpd and then reboot my now diskless linux machine.

Thanks again for your help,


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