Comment 4 for bug 1525138

So I've taken a closer look and this looks like a problem with environment configuration.

Cinder node (effectively, a compute node running cinder-volume):

10: br-storage: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default
    link/ether 64:28:fb:8b:0e:ea brd ff:ff:ff:ff:ff:ff
    inet 10.109.2.1/24 brd 10.109.2.255 scope global br-storage
       valid_lft forever preferred_lft forever
    inet6 fe80::5c99:bdff:fe68:426/64 scope link
       valid_lft forever preferred_lft forever

root@node-1:~# netstat -nalp | grep 3260
tcp 0 0 0.0.0.0:3260 0.0.0.0:* LISTEN 15345/tgtd
tcp6 0 0 :::3260 :::* LISTEN 15345/tgtd

root@node-1:~# telnet 10.109.2.1 3260
Trying 10.109.2.1...
Connected to 10.109.2.1.
Escape character is '^]'.
^]
telnet>

Everything works fine from the same host.

Nova compute node (the one an instance is running on):

root@node-2:~# telnet 10.109.2.1 3260
Trying 10.109.2.1...
telnet: Unable to connect to remote host: Connection refused

No connectivity from other host.

Here we can see that this IP address is actually configured on two different hosts:

root@node-3:~# arping 10.109.2.1
ARPING 10.109.2.1
60 bytes from 52:54:00:7b:88:aa (10.109.2.1): index=0 time=203.450 msec
60 bytes from 52:54:00:7b:88:aa (10.109.2.1): index=1 time=1.001 sec
60 bytes from 64:28:fb:8b:0e:ea (10.109.2.1): index=2 time=3.293 usec
60 bytes from 52:54:00:7b:88:aa (10.109.2.1): index=3 time=1.001 sec
60 bytes from 64:28:fb:8b:0e:ea (10.109.2.1): index=4 time=1.001 sec

And node-2 is really trying to connect to the host system, not to another slave:

root@node-2:~# ssh 10.109.2.1
/* *\
  Welcome to the Product server srv44-bud.infra.mirantis.net

  Please note:
    * You have to upload your key to auth.mirantis.com to access here.
    * Key deploying procedure takes up to 1 hour.
    * All actions are logged and tracked.
    * We're NOT granting sudo to anyone except Product DevOps team.

  On any questions please do not hesitate to contact.
  --
  #infra @Slack
  #fuel-infra @Freenode
\* */
root@10.109.2.1's password:

On the host:

(venv-nailgun-tests-2.9)rpodolyaka@srv44-bud:~$ ip a | grep 10.109.2.1
    inet 10.109.2.1/24 brd 10.109.2.255 scope global fuelbr2158