iscsid



ISCSID(8)                                                            ISCSID(8)




NAME

       iscsid - establish iSCSI connections


SYNOPSIS

       iscsid  [ -b bindingfile ] [ -d ] [ -f configfile ] [ -l basedir ] [ -m
       mode ] [ -n ]



DESCRIPTION

       iscsid  establishes  connections  with   iSCSI   targets   defined   in
       /etc/iscsi.conf.

       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-
              nel module.

       -      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!



DEVICE NAMES

       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
       units.




TARGET BINDINGS

       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.


OPTIONS

       -b bindingfile
              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).

       -f configfile
              Specify   an   alternative   configuration   file   instead   of
              /etc/iscsi.conf, which is the default.

       -l basedir
              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.

       -m mode
              Specify the directory permission mode (in  octal)  to  use  when
              creating directories.

       -n     Avoid auto-backgrounding.

       -v     Print version and exit.



SIGNALS

       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‘


       SIGTERM
              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
              sessions.

       SIGCHLD
              Wait for children.



NOTES

       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:

       http://linux-iscsi.sourceforge.com/


FILES

       /etc/iscsi.conf
              target address and LUN configuration

       /var/run/iscsi.pid
              the process id of the running daemon

       /var/iscsi/bindings
              persistent bus and target id bindings for iSCSI TargetNames

       /proc/scsi/iscsi
              information about iSCSI devices

       /dev/iscsi
              a directory tree containing symlinks to iSCSI device nodes.


SEE ALSO

       iscsi.conf(5)




$Revision: 1.8 $         $Date: 2002/09/20 19:27:32 $                ISCSID(8)

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