This section summarizes the representation of SCSI devices by our generic SCSI driver.
A computer can use several SCSI controllers for multiple SCSI buses. Each SCSI bus has 8 IDs, named 0-7. Normally, each device on a SCSI bus requires a SCSI ID. Jukeboxes often need one ID per drive and one for the robot.
Warning: When you connect devices to the bus, be sure the new devices use IDs that are not being used by existing devices on the controller. If you use an occupied ID, you can damage your hardware.
Usually, the SCSI controller occupies ID 7, 0-6 are free for devices. SGI
computers occupy ID 0, which means you can connect devices using IDs 1-7.
Each SCSI ID can be split into 8 logical unit numbers (LUNs). The advantage of
LUNs is that a jukebox only has to use one SCSI ID, allowing you to attach more
devices to a single bus.
Under
UNIX and NT, each device is represented by a device name, which is a path in
the root file system tree.
SCSI devices in NT
NT hides the devices. iXOS-JUKEMAN makes the names visible. The SCSI ID x on
bus y of controller z is represented by the path
\\.\pzbytx. So if you have a PCI bus and put Adaptec
twin adapters AHA 3940 into bus slots 0 to 2, you will have 6 SCSI buses, and
ID 4 on bus 1 of adapter 2 is represented as \\.\p2b1t4. Each
enumeration begins with 0. Within an ID, LUNs are represented by appending a
comma and the LUN. So \\.\p2b1t4,1 is LUN 1 of SCSI ID 4.
\\.\p2b10t4 and \\.\p2b1t4,0 are the same.
SCSI devices in UNIX
Under UNIX, all devices are located in a subdirectory of /dev. iXOS-JUKEMAN creates directories such as /dev/iXOS_SCSI0, /dev/iXOS_SCSI1, and so on. Each directory represents a SCSI bus. Devices are represented by numbers. So if your bus is represented by /dev/iXOS_SCSI1, the device using SCSI ID 4 is represented as /dev/iXOS_SCSI1/4. If you use LUNs, add a comma and the LUN number. /dev/iXOS_SCSI1/4,1 is LUN 1 of the device using SCSI ID 4 on bus /dev/iXOS_SCSI1.
SCSI device representation for iXOS-JUKEMAN | |
NT |
UNIX |
\\.\p<P>b<B>t<T>,<L> |
/dev/iXOS_SCSI<B>/<T>,<L> |
(<P>=adapter, <B>=bus, <T>=SCSI ID, <L>=LUN) |
If you know which paths represent your devices, you can use the inquiry command (in the JUKEMAN directory) to verify the paths. For example, if you have an HP Sure Store Recorder 4020i that is connected to the only SCSI bus on an NT system using SCSI ID 5, the command
inquiry \\.\p0b0t5
will return something like
0000002 \\.\p0b0t5 is HP's CD-drive "C4324/C4325"
0000004 ProRevL 1.25, Firmware 04/15/96
The first line gives the drive type, the second line gives the firmware
version.
0000000 Can't open \\.\p0b0t5
occurs if the driver is not running, the path is wrong, the device does not
work, the termination is wrong, or the cable is bad. The device may also be
unknown if it was not running when you booted the system.
If you do not know the paths that represent your devices, call
scsidevs
It returns a complete list of all known working SCSI devices. If you add a new controller, you can use these commands to check whether the path names have changed.