iscsi.bindings(5)
NAME
iscsi.bindings - SCSI targetId and the iSCSI target bind
ing information.
SYNOPSIS
/var/lib/iscsi/bindings
DESCRIPTION
This manual page describes the intent for having the
iscsi.bindings file and the format of this file.
INTENT
The Linux iSCSI driver creates SCSI device nodes dynami
cally whenever a SCSI logical unit is detected.
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.cis
- co.00.7e9d6f942e45736be69cb65c4c22e54c.disk0
- The first entry binds target id 1 on bus 1 to iSCSI target
- iqn.1987-05.com.cis
- co.00.7e9d6f942e45736be69cb65c4c22e54c.disk0.
- During target discovery if an entry for a given target ex
- ists 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 exam
ple 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.