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SCSI(7) Miscellaneous Information Manual SCSI(7) NAME SCSI, RAID - Small Computer System Interface SYNOPSIS nn# DESCRIPTION The operating system interfaces to disk and tape devices through the Small Computer System Interface (SCSI). Initial SCSI support is lim- ited to the Digital-supplied mass storage devices. The following de- vices are fully supported on the operating system: Winchester disks: RZ24L, RZ25, RZ25L, RZ25M, RZ26, RZ26L, RZ26N, RZ28, RZ28B, RZ28M, RZ29B, RZ55, RZ56, RZ58, RZ73, RZ74, RX23, RX26, RX33 RAID (Redundant Arrays of Independent Disks) SCSI controllers: HSZ10, HSZ40 Magnetic tapes: TZ30, TZ85, TZ86, TZ87, TZK10, TZK11, TLZ04, TLZ06, TLZ07, TSZ07, TKZ08, TKZ09 Optical disks: RRD42, RRD43, RRD44 Refer to your Software Product Description (SPD) for information on processor-specific device support. Under the operating system, a SCSI device is referred to by its logical name. Logical names take the following form: nn# The nn argument is the two-character name; the number sign (#) represents the unit number. An example of an rz SCSI disk would be the RZ24L. An example of a tz SCSI magnetic tape would be the TZK11. The unit number is a combination of the SCSI bus number (either 0, 1, and so on) and the device's target ID number. The unit number is eight times the bus number plus the target ID. For example, an RZ26 disk at target ID 3 on bus 0 would be referred to as rz3; a TLZ04 tape at tar- get ID 5 on the second SCSI bus would be referred to as 13. The SCSI bus has eight possible target device IDs. By default, one is allocated to the system. This allows for a maximum of seven target de- vices connected to a SCSI bus. SCSI LUN support The SCSI driver supports Logical Unit Numbers (LUNs) but there is only a limited predefined logical naming scheme, so you may need to use the following procedure to create the device special files for non-disk de- vices that do not use a LUN of zero. SCSI RAID controllers typically are capable of multiple LUNS per target identifier. The /dev/MAKEDEV command creates device special files for all the de- vices that are attached to a maximum of 16 SCSI controllers. The MAKEDEV command can create any LUN for disk devices and only LUN 0 for tape devices. The following diagram describes the minor numbers for SCSI disk de- vices: ---------------------------------------------------------- Bits: | 19 14 | 13 10 | 9 6 | 5 0 | ---------------------------------------------------------- | Bus no. | Target ID | LUN | Partition no. | ---------------------------------------------------------- The following diagram describes the minor numbers for SCSI tape de- vices: ----------------------------------------------------------- Bits: | 19 14 | 13 10 | 9 6 | 5 1 | 0 | ----------------------------------------------------------- | Bus no. | Target ID | LUN | Density | No rewind | ----------------------------------------------------------- To create the device special files for the device you want to add, use the previous diagrams to calculate the minor number value. If you want to add a disk device, you must create the character and block device files for each partition. If you want to add a tape device, you must create the device special files for each density and for no rewind. To add a device, you must use the following equation: (LUN x 64) + (target ID x 1024) + (bus no. x 16384) + partition no. Disk LUN support uses the form rzx#p and rrzx#p, where rrz is the SCSI name; x is the disk LUN; # is the rz number (bus * 8) + target; p is the partition name, a through h. The disk LUNs are as follows: b = lun 1 c = lun 2 d = lun 3 e = lun 4 f = lun 5 g = lun 6 h = lun 7 Create the disk block special files using the /dev/MAKEDEV command. For example: MAKEDEV rz20 Where rz = scsi, c = lun3, and 20 = (bus2 * 8) + target4. To add a tape device, you must use the following equation: (LUN x 64)+(target ID x 1024)+(bus no. x 16384)+(density x 2)+no_rewind The following example uses the previous formula to add a SCSI tape device with bus number 2, target ID 4, and LUN 3: Perform the calculations for the rewind device files: Density low: (3x64) + (4x1024) + (2x16384) + (0x2) + 0 = 37056 high: (3x64) + (4x1024) + (2x16384) + (1x2) + 0 = 37058 med: (3x64) + (4x1024) + (2x16384) + (2x2) + 0 = 37060 aux: (3x64) + (4x1024) + (2x16384) + (3x2) + 0 = 37062 Perform the calculations for the no rewind device files: Density low: (3x64) + (4x1024) + (2x16384) + (0x2) + 1 = 37057 high: (3x64) + (4x1024) + (2x16384) + (1x2) + 1 = 37059 med: (3x64) + (4x1024) + (2x16384) + (2x2) + 1 = 37061 aux: (3x64) + (4x1024) + (2x16384) + (3x2) + 1 = 37063 Create the tape rewind device special files: # mknod /dev/rmt?l c 9 37056 # mknod /dev/rmt?h c 9 37058 # mknod /dev/rmt?m c 9 37060 # mknod /dev/rmt?a c 9 37062 Create the tape no rewind device special files: # mknod /dev/nrmt?l c 9 37057 # mknod /dev/nrmt?h c 9 37059 # mknod /dev/nrmt?m c 9 37061 # mknod /dev/nrmt?a c 9 37063 RESTRICTIONS The SCSI device driver is not warrantied to operate with optical disks other than the Digital-supplied devices. The SCSI driver attempts to support, on a best-effort basis, non-Digi- tal-supplied Winchester disks and magnetic tapes. The following notes apply to the driver's handling of non-Digital-sup- plied disks: These disks are assigned a device type of RZxx instead of the Digital-supplied disk names listed previously (for example, RZ55). The RZxx disks follow the same logical device-naming scheme as the Dig- ital-supplied disks. During the autoconfigure phase of system startup, the driver displays the contents of the SCSI vendor ID, product ID, and the revision level fields of the inquiry data return by the SCSI de- vice. Also, the bus number, target ID, and LUN are displayed. To con- figure an RZ device or RAID controller so that LUNS are displayed dur- ing the autoconfigure phase of system startup, the configuration file that your kernel is generated from must be modified to reflect LUNS other than zero. The following is an example of a SCSI HSZ10 RAID con- troller at bus number 3, target ID 1, LUNs 0, 1, and 2: device disk rz25 at scsi3 drive 192 device disk rz25 at scsi3 drive 193 device disk rz25 at scsi3 drive 194 RZxx disks are assigned a default partition table. The default table can be modified by editing the ccmn_rzxx_sizes[8] entry in the /usr/sys/data/cam_data.c file. The disklabel command can also be used to modify the partition table on an RZxx disk. RELATED INFORMATION rz(7), tz(7), disklabel(8) delim off SCSI(7)