[JDSS] iSCSI target LUN unmonitored by multipath daemon on Linux client

Additional information:

product name: Open-E JovianDSS

Problem:

iSCSI LUN device is not listed under the 'multipathd show paths' and multipath monitoring cannot be enabled for connected iSCSI LUN device.

Symptoms:

'multipathd show paths' does not show the output for the connected iSCSI LUN device.
'multipathd show devices' lists the iSCSI LUN device as monitored which is not true:

sdq devnode whitelisted, monitored

When trying to enable monitoring manually a following error occurs:

$ sudo multipathd add path sdq

blacklisted

After running multipath with verbose 10 it shows that the device lacks udev rule:

multipath -v 10

2938.009606 | sdq: blacklisted, udev property missing

Solution:

Multipath has a default rule to block all devices, which lack "SCSI_IDENT_" and "ID_WWN" option in udev (https://man.archlinux.org/man/multipath.conf.5.en#property):

The default blacklist exception is: (SCSI_IDENT_|ID_WWN), causing well-behaved SCSI devices and devices that provide a WWN (World Wide Number) to be included, and all others to be excluded.

Add the following to /etc/multipath.conf:

blacklist_exceptions {

property "(SCSI_IDENT_|ID_WWN|ID_SERIAL)"

}