iscsid - establish iSCSI connections
iscsid [ -b bindingfile ] [ -d ] [ -f configfile ] [ -l basedir ] [ -m
mode ] [ -n ]
iscsid establishes connections with iSCSI targets defined in
Once the Linux iSCSI driver is activated, a discovery process for iSCSI
storage devices will proceed as follows:
- The iSCSI daemon requests available iSCSI targets from the iSCSI
target, and passes the information discovered to the iSCSI ker-
- The iSCSI kernel module establishes connections to the targets.
- Linux queries targets for device information.
- Linux creates a mapping from SCSI device nodes to iSCSI targets.
iscsid should be started after networking is configured and stopped
after all iSCSI devices have been unmounted.
Warning: Data corruption can occur if you do not unmount iSCSI devices
before disabling network interfaces!
Because Linux assigns SCSI device nodes dynamically whenever a SCSI
logical unit is detected, the mapping from device nodes (e.g /dev/sda,
/dev/sdb) to iSCSI targets and logical units may vary.
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 applica-
tions 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 a more reliable namespace, the iSCSI driver will scan the
system to determine the mapping from SCSI device nodes to iSCSI tar-
gets, and then create a tree of directories and symbolic links under
/dev/iscsi to make it easier to use a particular iSCSI target’s logical
The iSCSI driver automatically maintains a bindings file
/var/iscsi/bindings. This file contains persistent bindings to ensure
that the same iSCSI bus and target id number are used for every iSCSI
session to a particular iSCSI TargetName, no matter how many times the
driver is restarted.
This feature ensures that the SCSI numbers in the device symlinks
described above will always map to the same iSCSI target.
Note that because of the way Linux dynamically allocates SCSI device
nodes as SCSI devices are found, the driver does not and can not ensure
that any particular SCSI device node (e.g. /dev/sda) will always map to
the same iSCSI TargetName. The symlinks described in the section on
Device Names are intended to provide a persistent device mapping for
use by applications and fstab files, and should be used instead of
direct references to particular SCSI device nodes.
If the bindings file grows too large, lines for targets that no longer
exist may be manually removed by editing the file. Manual editing
should not normally be needed, since the driver can maintain up to
65535 different bindings.
Specify an alternative bindings file instead of /var/iscsi/bind-
ings, which is the default.
-d Turns on debug mode. Each occurence of -d will increment the
debug level by one. The default is zero (off).
Specify an alternative configuration file instead of
/etc/iscsi.conf, which is the default.
Specify the base directory under which to build a tree of direc-
tories containing symlinks to SCSI device nodes, in a manner
similar to the devfs Linux kernel option. Using these symlinks
hides variations in the mapping from SCSI device nodes to SCSI
device id numbers.
Specify the directory permission mode (in octal) to use when
-n Avoid auto-backgrounding.
-v Print version and exit.
iscsid reacts to a set of signals. You may easily send a signal to
iscsid using the following:
kill -SIGNAL ‘cat /var/run/iscsid.pid‘
The daemon and all of it’s children will die.
SIGHUP sent to the main daemon process will restart all discovery pro-
cesses and reprobe LUNs on all targets. iscsid and all of it’s
children will die after shutting down all of the kernel’s iSCSI
Wait for children.
The iSCSI Driver for Linux provides IP access to a maximum of sixteen
remote SCSI targets. Each target will be probed for up to 256 LUNs,
until the Linux kernel’s limit of SCSI devices has been reached.
The iSCSI drivers, README files, and example configuration files are
available on the Linux-iSCSI homepage at:
target address and LUN configuration
the process id of the running daemon
persistent bus and target id bindings for iSCSI TargetNames
information about iSCSI devices
a directory tree containing symlinks to iSCSI device nodes.
$Revision: 1.8 $ $Date: 2002/09/20 19:27:32 $ ISCSID(8)
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