[Bug 208469] [NEW] open-iscsi can fail to start if any portals are unavailable, even if other portals are fine

[LinuxBladeGuy]

Public bug reported:

Binary package hint: open-iscsi

Many enterprise-class iSCSI systems use multiple portals to access a
single target.  For example you can have 2 or 3 different network
pathways to a target, each with its own portal IP.  open-iscsi supports
this fine, however the current startup scripts do not handle pathway
failure gracefully.

Imagine this scenario:

A target: iqn.2008-03.com.something.target.t

3 portals:

10.0.3.1
10.0.7.1
10.0.10.1

On startup, open-iscsi goes through the list of portals and brings them
up one by one.  It seems to progress in alphabetical order, so in the
case above 10.0.10.1 will start up first.  Once the session has been
established to that portal, open-iscsi will proceed to the next portal,
and so on.  Once we are up and running, multipath handles portal
failures, load balancing, etc.  After boot time we can safely kill off 2
of the 3 portals and we still have a pathway to our iSCSI volume.

At boot time however, open-iscsi will fail to start if it hits a portal
that cannot be reached.  In the case above where we have a triple-
redundant portal we only need one of the 3 portals to be "alive".
However, as soon as open-iscsi hits a "dead" portal it will exit with a
failure and will not proceed to the next portal.  This actually provides
significantly LOWER reliability as we could easily have one portal
offline for maintenance, etc without impacting running systems, but no
other systems would be able to start up or be rebooted even though the
SAN itself is still operational!

** Affects: open-iscsi (Ubuntu)
     Importance: Undecided
         Status: New

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open-iscsi can fail to start if any portals are unavailable, even if other portals are fine
https://bugs.launchpad.net/bugs/208469
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