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NexentaStor 1.0.5 (Default branch)
07-29-2008
NexentaStor leverages the ZFS file system and is optimized for use in 2nd-tier NAS and iSCSI applications requiring open, low cost, high performance storage as well as dramatically simplified provisioning, expansion, backup, replication, and archiving. It is also used as a primary NAS in businesses that wish to expand at closer to commodity pricing. It supports unlimited snapshots, snapshot mirroring (replication), block level mirroring, integrated search, and easy management of extremely large storage pools. License: Other/Proprietary License with Free Trial Changes:|
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ISCSID(8) System Manager's Manual 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 kernel 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 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 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 logi- cal 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/bindings, 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 directories 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 processes and reprobe LUNs on all targets. iscsid and all of it's chil- dren 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/ <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)