HP EVA Array iSCSI Connectivity Option - Manual (Page 79)

NOTE:
The Linux driver supports both Red Hat 3 and SUSE 8. See the Readme file in the tar ball for more
information on how to configure the Linux iSCSI Initiator.
Installing the iSCSI driver
In a newly installed Red Hat Linux kernel, an iSCSI instance may be running. Before installing the
iSCSI driver, you must stop the instance.
To stop the instance:
1. Run setup.
2. Deselect iSCSI.
3. Reboot the system.
See the Readme file in the tar ball for more information on configuring the iSCSI Initiator.
To install the iSCSI driver:
1. Use tar(1) to decompress the source archive into a directory of your choice. The archive contains
a subdirectory corresponding to the archive name. Use the following commands to decompress the
source archive:
cd /usr/src
tar xvzf /path/to/linux-iscsi-version.tgz
cd linux-iscsi-<version>
2. Compile the iSCSI driver. If your kernel sources are not in the usual place, add
TOPDIR=/path/to/kernel
or edit the definition of TOPDIR in Makefile. Use the Make
command to edit Makefile.
3. Install the driver as root. If you are currently using the iSCSI driver, first unmount all iSCSI devices
and unload the old iSCSI driver. If your Linux distribution includes an iSCSI driver, it may be
necessary to uninstall that package first.
4. Configure the driver. See Installing and configuring for RedHat 3, 4 and SuSE 8 and 9 , page 78.
Assigning device names
Because Linux assigns SCSI device nodes dynamically whenever a SCSI logical unit is detected, the
mapping from device nodes such as /dev/sda or /dev/sdb to iSCSI targets and logical units may vary.
Variations in process scheduling and network delay can 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 can result in
sending SCSI commands to the wrong target or logical unit.
To provide consistent naming, the iSCSI driver scans the system to determine the mapping from SCSI
device nodes to iSCSI targets. The iSCSI driver creates a tree of directories and symbolic links under
/dev/iscsi
to make it easier to use a particular iSCSI target's logical unit.
The directory tree under /dev/iscsi contains subdirectories for each iSCSI bus number, each target id
number on the bus, and each logical unit number for each target. For example, the whole disk device for
bus 0
, target ID 0, and LUN 0 would be /dev/iscsi/bus0/target0/LUN0/disk.
In each logical unit directory there is a symbolic link for each SCSI device node that can be connected to
that particular logical unit. These symbolic links are modeled after the Linux devfs naming convention:
• The symbolic link disk maps to the whole-disk SCSI device node such as /dev/sda or /dev/sdb.
• The symbolic links part1 through part15 maps to each partition of that SCSI disk. For example, a
symbolic link can map to partitions /dev/sda1, dev/sda15, or to as many partitions as necessary.
EVA iSCSI connectivity user guide 79