rz(7) — Special Files
NAME
rz − SCSI disk interface
SYNOPSIS
DEC 7000 DEC XZA:
bus xmi0 at iop0 vector xmierror
bus xza0 at xmi?
controller skz0 at xza0
controller skz0 at xza0
tape tz0 at xza0 drive 0 DEC 4000 DEC SIOP:
bus ibus0 at nexus?
bus lbus0 at ibus0?
controller siop0 at lbus0 slot 0 vector siopcointr
tape tz0 at siop0 drive 0 DEC 3000 NCR ASC:
bus tc0 at nexus?
controller asc0 at ∗ vector tcdsintr
tape tz0 at asc0 drive 0 DEC 3000 DEC KZTSA:
controller tzan at ∗ vector kztsa_intr
controller tzan at ∗ vector kztsa_intr
disk rznn at tzan drive nnn
disk rznn at tzan drive nnn
tape tznn at tzan drive nnn
tape tznn at tzan drive nnn
DESCRIPTION
The rz driver is for all Digital Small Computer System Interface (SCSI) disk drives.
The following rules are used to determine the major and minor numbers that are associated with an rz type disk. There is one major number used to represent rz disks. The minor number is used to represent both the SCSI unit number and partition. A disk partition refers to a designated portion of the physical disk. To accomplish this, the 20-bit minor number is broken up into two parts. The low six bits of the minor number specify a disk partition. The partitions use a letter, a through h, as their name. The next 14 bits of the minor number specify the SCSI unit number within a group of 128 disks.
The device special file names associated with rz disks are based on conventions that are closely associated with the minor number assigned to the disk. The standard device names begin with rz for the block special file and rrz for the raw (character) special file. Following the rz is the logical unit number (LUN) and then a letter, a through h, that represents the partition. Throughout this reference page, the question mark (?) character represents the logical unit number in the name of the device special file. For example, rz?b could represent rz0b, rz1b, and so on.
The SCSI unit number can be calculated if the major and minor number of an rz disk is provided. For example, for the device special file rrz6a, the major number is 8 and the minor number is 6144. The partition is represented by the lower six bits of the number 6144. The lower six bits are 0, which specifies the a partition. The next four bits of the minor number 6144 specify the SCSI logical unit number, which is 0. The next four bits of 6144 specify the target ID of 6. The next six bits specify the SCSI bus number, which is 0. Because 8 is the base major number, it represents the group of 128 disks. Putting all these pieces together reveals that the major/minor number pair 8/6144 refers to the a partition of SCSI unit 6.
A disk can be accessed through either the block special file or the character special file. The block special file accesses the disk using the file system’s normal buffering mechanism. Reads and writes to the block special file can specify any size. This avoids the need to limit data transfers to the size of physical disk records and to calculate offsets within disk records. The file system can break up large read and write requests into smaller fixed-size transfers to the disk.
The character special file provides a raw interface that allows for direct transmission between the disk and the user’s read or write buffer. A single read or write to the raw interface results in exactly one I/O operation. Consequently, raw I/O may be considerably more efficient for large transfers.
For systems with SCSI disks, the first software boot after the system is powered on may take longer than expected. This delay is normal and is caused by the software spinning up the SCSI disk drives.
Disk Support
This driver handles all disk drives that can be connected to the SCSI bus. Consult the Software Product Description (SPD) to determine which drives are supported for which CPU types and hardware configurations.
SCSI RAID Controllers are viewed in most cases as RZ-type disks. There are some differences that should be taken into consideration when configuring a RAID device:
•Currently, only sector sizes of 512 bytes are supported.
•Logical Volume sizes are not a fixed size as compared to other SCSI disk devices. The size of the Logical Volume is configurable based on needs. The DYNAMIC nature of Logical Volume sizes is dealt with by defining RAID devices as DYNAMIC. Only partitions a, b, c, and g are defined. If needed, the disklabel(8) command can be run to change and define partitions for RAID devices.
Usually, the rz?a partition is used for the root file system and the rz?b partition as a paging area. The rz?c partition can be used for disk-to-disk copying because it maps the entire disk.
The starting location and length (in 512-byte sectors) of the disk partitions of each drive are shown in the following tables. Partition sizes can be changed by using the disklabel(8) command.
RZ24L Partitions for Systems Based on
the Alpha AXP Architecture
DiskStartLength
rz?a040960
rz?b40960122880
rz?c0479350
rz?d163840105170
rz?e269010105170
rz?f374180105170
rz?g163840315510
rz?h00
RZ25 Partitions for Systems Based on
the Alpha AXP Architecture
DiskStartLength
rz?a0131072
rz?b131072262144
rz?c0832527
rz?d393216146437
rz?e539653146437
rz?f686090146437
rz?g393216439311
rz?h00
RZ25L Partitions for Systems Based on
the Alpha AXP Architecture
Disk Start Length
rz?a0131072
rz?b131072262144
rz?c01046206
rz?d393216217663
rz?e610879217663
rz?f828542217664
rz?g393216652990
rz?h0 0
RZ26 Partitions for Systems Based on
the Alpha AXP Architecture
DiskStartLength
rz?a0131072
rz?b131072262144
rz?c02050860
rz?d393216552548
rz?e945764552548
rz?f1498312552548
rz?g393216819200
rz?h1212416838444
RZ26L Partitions for Systems Based on
the Alpha AXP Architecture
Disk Start Length
rz?a0131072
rz?b131072262144
rz?c02050860
rz?d393216552548
rz?e945764552548
rz?f1498312552548
rz?g393216819200
rz?h1212416838444
RZ28 partitions for Systems Based on
the Alpha AXP Architecture
Disk Start Length
rz?a0131072
rz?b131072401408
rz?c04110480
rz?d5324801191936
rz?e17244161191936
rz?f29163521194128
rz?g5324801787904
rz?h23203841790096
RZ28B Partitions for Systems Based on
the Alpha AXP Architecture
Disk Start Length
rz?a0131072
rz?b131072401408
rz?c04110480
rz?d5324801191936
rz?e17244161191936
rz?f29163521194128
rz?g5324801787904
rz?h23203841790096
RZ55 Partitions for Systems Based on
the Alpha AXP Architecture
DiskStartLength
rz?a0131072
rz?b131072262144
rz?c0649040
rz?d00
rz?e00
rz?f00
rz?g393216255824
rz?h00
RZ56 Partitions for Systems Based on
the Alpha AXP Architecture
DiskStartLength
rz?a0131072
rz?b131072262144
rz?c01299174
rz?d393216301986
rz?e695202301986
rz?f997188301986
rz?g393216819200
rz?h121241686758
RZ58 Partitions for Systems Based on
the Alpha AXP Architecture
DiskStartLength
rz?a0131072
rz?b131072262144
rz?c02698061
rz?d393216768281
rz?e1161497768282
rz?f1929779768282
rz?g393216819200
rz?h12124161485645
RZ73 Partitions for Systems Based on
the Alpha AXP Architecture
DiskStartLength
rz?a0131072
rz?b131072262144
rz?c03907911
rz?d3932161171565
rz?e15647811171565
rz?f27363461171565
rz?g393216819200
rz?h12124162695495
RZ74 Partitions for Systems Based on
the Alpha AXP Architecture
Disk Start Length
rz?a0131072
rz?b131072393216
rz?c06976375
rz?d5242882150400
rz?e26746882150400
rz?f48250882151287
rz?g5242883225600
rz?h37498883226487
HSZ10 (RAID) Partitions for Systems Based on
the Alpha AXP Architecture
DiskStartLength
rz?a0131072
rz?b131072262144
rz?c0end of media
rz?d00
rz?e00
rz?f00
rz?g393216 end of media
rz?h00
RRD42 (Read-Only) Partitions (CD-ROM)
DiskStartLength
rz?a0(size varies per CD)
rz?b00
rz?c0(size varies per CD)
rz?d00
rz?e00
rz?f00
rz?g00
rz?h00
RRD43 (Read-Only) Partitions (CD-ROM)
Disk Start Length
rz?a0(size varies per CD)
rz?b00
rz?c0(size varies per CD)
rz?d00
rz?e00
rz?f00
rz?g00
rz?h00
RRD44 (Read-Only) Partitions (CD-ROM)
Disk Start Length
rz?a0(size varies per CD)
rz?b00
rz?c0(size varies per CD)
rz?d00
rz?e00
rz?f00
rz?g00
rz?h00
RX23 Partitions (High-Density)
DiskStartLength
rz?a02880
rz?b00
rz?c02880
rz?d00
rz?e00
rz?f00
rz?g00
rz?h00
RX23DD Partitions (Double-Density)
DiskStartLength
rz?a01440
rz?b00
rz?c01440
rz?d00
rz?e00
rz?f00
rz?g00
rz?h00
RX23SD Partitions (Single-Density)
DiskStartLength
rz?a0720
rz?b00
rz?c0720
rz?d00
rz?e00
rz?f00
rz?g00
rz?h00
RX26 Partitions (Extra-Density Floppy)
DiskStartLength
rz?a05760
rz?b00
rz?c05760
rz?d00
rz?e00
rz?f00
rz?g00
rz?h00
RX26HD Partitions (High-Density Floppy)
DiskStartLength
rz?a02880
rz?b00
rz?c02880
rz?d00
rz?e00
rz?f00
rz?g00
rz?h00
RX26DD Partitions (Double-Density Floppy)
DiskStartLength
rz?a01440
rz?b00
rz?c01440
rz?d00
rz?e00
rz?f00
rz?g00
rz?h00
RX26SD Partitions (Single-Density Floppy)
DiskStartLength
rz?a0720
rz?b00
rz?c0720
rz?d00
rz?e00
rz?f00
rz?g00
rz?h00
RX33 Partitions (Extra-Density)
DiskStartLength
rz?a02400
rz?b00
rz?c02400
rz?d00
rz?e00
rz?f00
rz?g00
rz?h00
RX33HD Partitions (High-Density)
DiskStartLength
rz?a01440
rz?b00
rz?c01440
rz?d00
rz?e00
rz?f00
rz?g00
rz?h00
RX33DD Partitions (Double-Density)
DiskStartLength
rz?a0800
rz?b00
rz?c0800
rz?d00
rz?e00
rz?f00
rz?g00
rz?h00
RX33SD Partitions (Single-Density)
DiskStartLength
rz?a0720
rz?b00
rz?c0720
rz?d00
rz?e00
rz?f00
rz?g00
rz?h00
EXAMPLES
The following example shows the configuration specification that you might have for a DEC 3000 Model 500 system with a PMAZB controller in slot 0 and KZTSA devices in slots 1 and 2:
bus tc0 at nexus?
controller tza4 at ∗ vector kztsa_intr
controller tza5 at ∗ vector kztsa_intr
disk rz32 at tza4 drive 256
disk rz40 at tza5 drive 320
tape tz32 at tza4 drive 256
tape tz40 at tza5 drive 320
FILES
/dev/rz???
/dev/rrz???
/etc/disktab