Allow disabling auto LUN scans

Existing behavior of auto scanning LUNs is problematic for some
deployments, particularly in cases where we are:

- Accessing different LUNs from the same target on different machines
  and we don't want the other LUNs automatically exposed in other
  systems.

- LUNs are constantly being created and removed from the target by
  another machine and we don't want our systems polluted by no longer
  available logical units, since default udev rules don't remove them
  automatically from the system once they have been added automatically.

This is a little more problematic when working with multipaths as we end
up with a lot of leftover device maps.

This patch introduces a new configuration option at the session level
called "scan", with "auto" and "manual" as acceptable values, that
allows us to disable the autoscan in the following cases:

- On iscsid start
- On login
- On AEN/AER messages reporting LUNs data has changed.

For HW drivers all sessions will use the value defined in the
configuration file.

Default value for this new option is "auto" to maintain existing
behavior.

1 files changed, 8 insertions, 0 deletions

diff --git a/etc/iscsid.conf b/etc/iscsid.conf
index f7ecb6b..cb77a77 100644
--- a/etc/iscsid.conf
+++ b/etc/iscsid.conf
@@ -305,3 +305,11 @@ node.session.iscsi.FastAbort = Yes
 # a task management function like an ABORT TASK or LOGICAL UNIT RESET, that
 # it continue to respond to R2Ts. To enable this uncomment this line
 # node.session.iscsi.FastAbort = No
+
+# To prevent doing automatic scans that would add unwanted luns to the system
+# we can disable them and have sessions only do manually requested scans.
+# Automatic scans are performed on startup, on login, and on AEN/AER reception
+# on devices supporting it.  For HW drivers all sessions will use the value
+# defined in the configuration file.  This configuration option is independent
+# of scsi_mod scan parameter. (The default behavior is auto):
+node.session.scan = auto