Now that was disappointing. An aging iSCSI bug has resurfaced in Debian's latest and greatest stable release, Wheezy, or in numbers 7. Its rendering Debian's iSCSI package useless. Upon scanning a Debian target using an initiator, e.g. ESXi's software iSCSI adaptor, the following messages pop up:
Jun 3 04:30:44 debian kernel: [ 242.785518] Pid: 3006, comm: istiod1 Tainted: G O 3.2.0-4-amd64 #1 Debian 3.2.41-2+deb7u2
Jun 3 04:30:44 debian kernel: [ 242.785521] Call Trace:
Jun 3 04:30:44 debian kernel: [ 242.785537] [<ffffffffa03103f1>] ? send_data_rsp+0x45/0x1f4 [iscsi_trgt]
Jun 3 04:30:44 debian kernel: [ 242.785542] [<ffffffffa03190d3>] ? ua_pending+0x19/0xa5 [iscsi_trgt]
Jun 3 04:30:44 debian kernel: [ 242.785550] [<ffffffffa0317da8>] ? disk_execute_cmnd+0x1cf/0x22d [iscsi_trgt]
With ESXi in particular eventually the lun will show up, after a bunch of timeouts, I suppose, but is not usable in any way and may disconnect at any time.
Thankfully there is a solution to the dilemma. Some Googleing around I found this again rather old thread in a Ubuntu forum describing the very same issue. Combined with the knowledge of the aforementioned bug I followed the instructions, grabbed the latest set of iscsitarget-dkms sources, compiled them and whatdoyouknow, it works like a charm.