[ipxe-devel] input/output error on iscsi sanboot from linux tgt

Dr. David Alan Gilbert dave at treblig.org
Sun Sep 2 18:41:10 UTC 2012

  I've got 2 KVM guests; both running the current Ubuntu Quantal server
test install (iso as of yesterday), and i'm trying to iSCSI boot
one from the other (on a Ubunqu Quantal x86-64 host)

When I try to use the sanboot command on the client I do:

sanboot iscsi:
Could not open SAN device: Input/output error (http://ipxe.org/1d704439).

Both VMs have 2 net interfaces; one in 192.168.122.x, and the other on
192.168.123.x; the server is

I've already dhcp'd OK, if I change any part of the iSCSI device name
it gives a device not found error, so it's talking to the server.

  The 1st one ('server1') is running the 'tgt' iSCSI target
stack, and serves a single LUN; here is it's config file:

<target iqn.2008-09.com.example:server1.share1>
    backing-store /dev/mapper/server1-share1

and is started with
tgtd --iscsi portal=,portal=

in it's upstart script.

The tgt is happy speaking to open-iscsi, indeed I've done a CD image
boot of an install on the client vm and it's done the full install over
iscsi, and I can bring up a 3rd VM and it get it to mount the
iSCSI device and it can see it.

There is a tcpdump capture here:


This trace is the result of running the sanboot command twice
(the first one ending at packet 61 I think).

The tcpdump was run on the server as

tcpdump host -s 16000 -w capture -U

Looking at this in wireshark I can see multiple read capacities
but I don't understand the last 4 packets of both sessions.

This is just me trying stuff in VMs, but any suggestions are

 -----Open up your eyes, open up your mind, open up your code -------   
/ Dr. David Alan Gilbert    |       Running GNU/Linux       | Happy  \ 
\ gro.gilbert @ treblig.org |                               | In Hex /
 \ _________________________|_____ http://www.treblig.org   |_______/

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