[Pkg-iscsi-maintainers] Bug#687619: iscsitarget restart fail if more than 32 session try reconnect

[Laszlo Fekete]

Package: iscsitarget
Version: 1.4.20.2-1


Hello!

I have fresh debian squeeze with standard 2.6.32-5-amd64 kernel and 
iscsitarget + iscsitarget-dkms packages and have some other squeeze with open-
iscsi initiators.
The problem is after a long testing, that if there is more than 32 active 
sessions when try /etc/init.d/iscsitarget restart, it sometimes fails, so no 
more than 32 initiator can reconnect.

For more details:
I have 16 targets with summary 40 active sessions, try to restart the iscsi 
target and sometimes (not all the time, 20-60% of the tries for me) it fail. 
first 32 clients can reconnect without problem, but the others don't get 
answer from the target and don't working. There is no error on target or 
initiator side, just the initiators try to reconnect.
There is two type of the initiators:
- using one session to access the target with only one ip, open-iscsi config 
limits and timeout are the default
- using 4 session to access the two target (some of the targets are duplicated 
within 2 servers with drbd) with 2 session/ip per target. These initiators 
using multipath and minimal (1sec) timeouts.
Both type contains sessions which are just connected, but the target isn't 
mounted on that client which failed to reconnect.

If the iscsi target restart fail it random which initiator stuck, I think it 
only depend on who is the faster to be in the first 32 session.
Tried to check, maybe this is a network connection, but if the restart fail 
and try to telnet to them sometimes it also don't answer (tcpdump show, that 
the target server got the request, but don't send any answer).

Checked that maybe on the iscsi target stop stucked, but it seems to be okay, 
the session closed, the modules unloaded, there isn't any error, tried to 
raise the sleep time before start to 10 sec from 1, but got the same error.

So I think there is a limit somewere that the in a short time no more than 32 
initiator can connect, but don't find any of this.
Checked the newer iscsi targets changelog and don't see any report that 
describe this problem, so don't tried to upgrade wheezy.

Debian GNU/Linux 6.0, kernel 2.6.32-5-amd64, libc 2.11.3-3

Thank you very much!

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