Thanks for the explanation.

The rescan seemed to do the trick.  I added it to the boot logic, and
caught a blade with this error just yesterday.  There are 9 LUNs, but
when this happens it is always LUN-0 that is missing.  A "- - -"
rescan found the missing LUN and created the new device (/dev/sdi).

The target is some funky custom box that no one else in the world
uses ;)
The iscsistart utility returns success, and creates a single session
with multiple LUNs.  The first one is occasionally missing (say 1 in
25 reboots).

I was wondering if our boot script is not waiting long enough between
loading the iscsi kernel modules, and running iscsistart.  I might
play with sleeping for a second between loading the last module, and
trying to make the connection.  Just in case it is a race condition.

Thanks for all the help,

On Mar 26, 8:32 am, Mike Christie <> wrote:
> agspoon wrote:
> > Thanks for the tip.  Yes, it really is LUN-0 that is missing.  All the
> > other LUNs (1-6) do show up in this error condition, and upon reboot
> > they all show up.  It is only an occasional boot up where I see LUN-0
> > missing, and I wanted to avoid a reboot to restore it.  I'll give the
> > re-scan trigger a try and see if LUN-0 shows up.
> > What is the magic with the "- - -" that triggers the scan?  A bit of
> It is :
> "-" is a wild card.
> For software iscsi the first two are going to be "-" or zero (iscsi
> always just uses 0), and then for LUN can you just use 0 if you are only
> looking for that one.
> You can also run iscsiadm
> iscsiadm -m session -r session_id --rescan
> or
> iscsiadm -m session --rescan
> to scan all sessions.
> > searching shows that many other people know about this, but I've
> > somehow missed it. Is there any documentation that describes this
> > interface (didn't see anything in the kernel docs)?
> > Craig
> > On Mar 25, 7:27 am, Konrad Rzeszutek <> wrote:
> >> On Wed, Mar 25, 2009 at 08:26:46AM +0100, Ulrich Windl wrote:
> >>> On 24 Mar 2009 at 19:47, agspoon wrote:
> >>>> We have an occasional problem where one LUN of a target (LUN-0) does
> >>>> not appear in a connection started by iscsistart.  This is in an iscsi-
> >>>> root scenario where iscsistart is called from within the initrd
> >>>> ramdisk image.  I don't why this happens, but I can detect when it
> >>>> does.  However, I don't know how to stop the connection and try
> >>>> again.  If I just re-run iscsistart, it complains that there is
> >>>> already a connection.  I tried just pulling out all the iscsi related
> >>>> modules and re-loading them, but they are "in use".
> >>> Hi!
> >>> I think that's not very iSCSI related, so my guess would be to keep the 
> >>> connection
> >>> and try a "rescan SCSI bus" on the SCSI host/connection that you already 
> >>> have.
> >>> Also, do you really need LUN 0? Disks are usually assigned to a LUN != 0.
> >> They are with some iSCSI targets (MD3000i, DS3300, AX150, CX300, 
> >> Compelant, DataCore,
> >> and some other ones).
> >> Do you have any other LUNs on the target except LUN-0? Do they show up?
> >> If not, you can do 'echo "- - -" > /sys/class/scsi_host/hostX/scan" to
> >> retrigger the scan. That should make the LUN-0 and others show up.
> >> You will have to figure out the hostX relation to 
> >> /sys/class/iscsi_session/sessionY
> >> yourself.
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