The driver does not and cannot ensure that any particular SCSI device node (e.g., /dev/sda) will always map to the same iSCSI TargetName. This can result in inconsistency while mapping from device nodes (e.g /dev/sda, /dev/rmt8) to iSCSI targets and logical units. Symlinks are provided by iSCSI driver for persistent device mapping which are used by applications and fstab files.

Variations in process scheduling and network delay may result in iSCSI targets being mapped to different SCSI device nodes every time the driver is started. Because of this variability, configuring applications or operating system utilities to use the standard SCSI device nodes to access iSCSI devices may result in SCSI commands being sent to the wrong target or logical unit.

To provide persistent binding between the iSCSI device and the physical device, the Linux iSCSI driver will create a mapping between SCSI targetId and iSCSI target names and will store the mapping in the file /var/lib/iscsi/bindings This mapping will be used every time the driver is started.

FORMAT

The file /var/lib/iscsi/bindings will have the entry that
binds a TargetId to a iSCSI target WWUI name.

EXAMPLE

Each line of the file /var/lib/iscsi/bindings will contain the following fields:
bus target targetname
An example file would look like:

0 1 iqn.1987-05.com.cisco.00.7e9d6f942e45736be69cb65c4c22e54c.disk0

The first entry binds target id 1 on bus 1 to iSCSI target

iqn.1987-05.com.cisco.00.7e9d6f942e45736be69cb65c4c22e54c.disk0.

During target discovery if an entry for a given target exists in the
file /var/lib/iscsi/bindings then the target is assigned the id. Else
the smallest available SCSI target ID is assigned on the smallest
available bus and an entry is written to the file. If all the target
IDs are exhausted on a particular bus, then the target ID will be
allocated on the next available bus.

EDITING

Note that these files will permanently contain entries for all iSCSI targets ever logged into from this host. If a target is no longer available to a host you can manually edit the file and remove entries so the obselete target no longer consumes a SCSI target ID. In the above shown example if you know that the target which was assigned target ID 0 is no longer available then you have to remove line 1 from /var/lib/iscsi/bindings

If you know the iSCSI WWUI name of a target in advance and you want it to be assigned a particular SCSI target ID, you can add an entry manually.

Note: You should stop the iSCSI driver before editing the these files.

Warning: Failure to adhere to above instructions while editing can result in unpredictable results.

ISCSI.BINDINGS

NAME

SYNOPSIS

DESCRIPTION

INTENT

FORMAT

EXAMPLE

EDITING

SEE ALSO