HP OpenVMS Systems Documentation

This chapter describes the use of disk drivers that support the diskdevices listed in the Software Product Description for the OpenVMSOperating System for Alpha and VAX. The chapter also includesdescriptions of many of the supported disks and controllers. However,not all supported devices are described here. Refer to the SoftwareProduct Description for the OpenVMS Operating System for Alpha andVAX for the definitive list of supported devices.

All disk drivers support Files-11 On-Disk Structure Level 1 and Level 2file structures. Access to these file structures is through the DCLcommands INITIALIZE and MOUNT, followed by the RMS calls described inthe OpenVMS Record Management Services Reference Manual. Files in RT-11 format can be read or written withthe file exchange facility EXCHANGE.

2.1 Supported Disk Devices and Controllers

The following sections provide descriptions of disk devices.

To obtain more information about a device, use the DCL command SHOW DEVICE with the /FULL qualifier, the Get Device/Volume Information ($GETDVI) system service (from a program), or the F$GETDVI lexical function (in a command line or command procedure). Section 2.3 lists the information on disk devices returned by $GETDVI.

2.1.1 UDA50 UNIBUS Disk Adapter

The UDA50 UNIBUS Disk Adapter is a microprocessor-based disk controllerfor mass storage devices that implements the DIGITAL StorageArchitecture (DSA); for more information on the DSA, see Section 2.2.3.

The UDA50 controller is used to connect any combination of four RA60,RA80, and RA81 disk drives to the UNIBUS. Two UDA50 controllers can beattached to a single UNIBUS for a maximum of eight disk drives perUNIBUS. On the VAX-11/780 processor, the operating system supports oneUDA50 on the first UNIBUS, which can accommodate certain other options.Adding a second UDA50 requires a second UNIBUS. With the exception ofthe first UNIBUS, a maximum of two UDA50 controllers per UNIBUS aresupported. If two UDA50 controllers are on a UNIBUS, no other optionscan be placed on that UNIBUS. The VAX-11/730 processor supports onlyone UDA50 per UNIBUS.

The UDA50, in implementing DSA, takes over the control of the physicaldisk unit. The operating system processes request virtual or logicalI/O on disks controlled by the UDA50. The operating system maps virtualblock addresses into logical block addresses. The UDA50 then resolveslogical block addresses into physical block addresses on the disk.

The UDA50 controller corrects bad blocks on the disk by requesting thatthe disk class driver revector a failing physicalblock to another, error-free physical block on the disk; the logicalblock number is not changed (see Section 2.2.11.1). Any bad blocks thatmight exist on a disk attached to a UDA50 are transparent to theoperating system, which does logical or virtual I/O to such a disk. TheUDA50 also corrects most data errors.

2.1.2 KDA50 Disk Controller

The KDA50 disk controller is a two-module disk controller that allowsthe RA-series DSA disk drives to be attached to Q-bus systems. TheKDA50 performs the same functions as the UDA50 (see Section 2.1.1).

2.1.3 KDB50 Disk Controller

The KDB50 disk controller is a two-module disk controller that allowsthe RA-series DSA disk drives to be attached to BI bus systems, such asthe VAX 8200 processor. The KDB50 performs the same functions as theUDA50 (see Section 2.1.1).

2.1.4 HSC40, HSC50, and HSC70 Controllers

HSC controllers are high-speed, high-availability controllers for massstorage devices that implement the DIGITAL Storage Architecture (DSA);for more information about the DSA, see Section 2.2.3. An HSCcontroller is connected to a processor by a CI bus (computerinterconnect). The operating system supports the use of the HSCcontrollers in controlling the RA family of disks.

The HSC40 can support up to 12 SDI (standard disk interface) disks fromthe SA or RA families of disk drives or a combination of up to 12 SDIdisk drives and TA-series tape drives.

The HSC70 can support up to 32 SDI disks from the SA or RA families ofdisk drives or a combination of SDI disk drives and TA-series tapedrives.

HSC controllers, in implementing DSA, take over the control of thephysical disk unit. System processes request virtual or logical I/O ondisks controlled by the HSC controller. The operating system mapsvirtual block addresses into logical block addresses. The HSCcontroller then resolves logical block addresses into physical blockaddresses on the disk.

HSC controllers correct bad blocks on the disk by revectoring a failingphysical block to another, error-free physical block on the disk; thelogical block number is not changed. The operating system, whichperforms logical or virtual I/O to such a disk, does not recognize thatany bad blocks might exist on a disk attached to an HSC controller. HSCcontrollers also correct most data errors.

The HSC series of controllers provides access to disks despite mosthardware failures. Use of an HSC controller permits two or moreprocessors to access files on the same disk.

HSC-series controllers allow you to add or subtract disks from thedevice configuration without rebooting the system.

2.1.5 SII Integral Adapter

The SII integral adapter on the MicroVAX 3300/3400 processor providesaccess through the DIGITAL Storage Systems Interconnect (DSSI) bus to amaximum of seven storage devices.

The term dual-host refers to pairs of CPUs connectedto a bus. In dual-host configurations of MicroVAX 3300/3400 CPUs, theDSSI bus must be connected between the SII integral adapters present onboth CPUs.

A maximum of six devices can be connected to the EDA640 adapter, whichis implemeneted by the SII chip, DXX chip, and 128K RAM chip, indual-host configurations.

2.1.6 KFQSA Adapter

The KFQSA adapter allows a maximum of seven storage devices for use onQ-bus systems.

In dual-host configurations of MicroVAX 3800/3900 CPUs, the DSSI busmust be connected between KFQSA adapters present on both CPUs.

A maximum of six devices can be connected to the KFQSA adapter indual-host configurations.

2.1.7 RQDX3 Disk Controller

The RQDX3 controller is a Q-bus controller used with the RD series ofWinchester-type disk drives and the RX33 and RX50 flexible diskettedrives.

2.1.8 RA70 and RA90 Disk Drives

The RA70 is a 5.25-inch 280 MB high-performance DSA disk drive thatuses thin-film media. It has an average access time of 27.0 ms andaverage seek time of 19.5 ms. The RA70 uses the Standard Disk Interface(SDI) and the KDA50 controller, and can be dual-ported.

The RA90 is a 1.2 GB disk drive designed with thin-film heads and9-inch thin-film media with an average seek time of 18.5 ms. The RA90conforms to DSA and uses the SDI. Both the RA70 and RA90 disk drivescan be connected to medium-sized systems with the HSC-seriescontrollers, KDB50, or UDA50 controllers.

2.1.9 RA60 Disk

The RA60 device uses high-capacity, removable media that provides 205MB of usable storage (7.5 million bits of data per square inch) withtransfer rates of 1.9 MB per second (burst) and 950 kb per second(sustained). The RA60 belongs to the DIGITAL Storage Architecture (DSA)family of disk devices (see Section 2.2.3). It is connected to either aUNIBUS Disk Adapter (UDA50) or an HSC50 controller. Up to four diskdrives can be connected to each UDA50. Up to 24 disk drives can beconnected to each HSC50.

2.1.10 RA80/RB80/RM80 and RA81 Fixed-Media Disks

The R80 disk drive is a high-capacity, moving-head disk whose nonremovable media consists of 14 data surfaces. Depending on how it is connected to the system, the R80 is identified internally as an RA80, RB80, or RM80, as follows:

• RA80---An R80 connected to the system through a UNIBUS disk adapter (UDA50) or an HSC50 controller. Up to four disk drives can be connected to each UDA50. Up to 24 disk drives can be connected to each HSC50.
• RB80---On VAX systems, an R80 connected to the system through an RB730 controller on a VAX-11/730 processor. Of the maximum of four drives that can be connected to an RB730 controller, only one can be an RB80.
• RM80---On VAX and Alpha systems, an R80 connected to the system through a MASSBUS adapter (MBA). Up to eight disk drives can be connected to each MBA.

The RA81 is a high-capacity disk drive with nonremovable media that can hold more than 890,000 blocks of data. This translates into more than 455 MB per spindle. The RA81 is connected to a UDA50 or an HSC50 controller. Up to four disk drives can be connected to each UDA50. Up to 24 drives can be connected to each HSC50.

The RA80 and RA81 belong to the DIGITAL Storage Architecture (DSA)family of disk devices (see Section 2.2.3).

2.1.11 RB02 and RL02 Cartridge Disk (VAX Only)

On VAX systems, the RL02 cartridge disk is a removable, random-accessmass storage device with two data surfaces. The RL02 is connected tothe system by an RL11 controller that interfaces with the UNIBUSadapter. Up to four RL02 disk drives can be connected to each RL11controller. For physical I/O transfers, the track, sector, and cylinderparameters describe a physical 256-byte RL02 sector (see Section 2.4).

When the RL02 is connected to an RB730 controller on a VAX-11/730processor, it is identified internally as an RB02 disk drive. Diskgeometry is unchanged and RL02 disk packs can be exchanged betweendrives on different controllers. Up to four drives can be connected tothe RB730 controller.

2.1.12 RC25 Disk (VAX Only)

On VAX systems, the RC25 disk is a self-contained, Winchester-type,mass storage device that consists of a disk adapter module, a diskdrive, and an integrated disk controller. The drive contains two8-inch, double-sided disks. One of the disks (RCF25) is a sealed,nonremovable, fixed-media disk. The other disk is a removable cartridgedisk that is sealed until it is loaded into the disk drive. The disksshare a common drive spindle, and together they provide 52 millionbytes of storage. Adapter modules interface the RC25 with either aUNIBUS system or a Q-bus system.

2.1.13 RD53 and RD54 Disks (VAX Only)

On VAX systems, the RD53 and RD54 are 5.25-inch, full-height, Winchester-type drives with average access time of 38 ms and a data transfer rate of 0.625 MB per second. The RD53 and RD54 have a formatted capacity of 71 MB and 159 MB, respectively. When used with the RQDX3 controller, the RD53 and RD54 are DSA disks.

See Section 2.2.12 for information about using RD series disks on theVAXstation 2000.

2.1.14 RF30 and RF71 Disks

The RF30 is a 150-MB, 5.25-inch, half-height disk drive while the RF71is a 400-MB full-height disk drive. The RF30 and RF71 include anembedded controller for multihost access and a mass storage controlprotocol (MSCP) server. The RF71 has a peak data transfer rate of 1.5MB per second with average seek and access time of 21 ms and 29 ms,respectively.

Both the RF30 and RF71 disks use DIGITAL Storage System Interconnect (DSSI) bus and host adapters.

2.1.15 RK06 and RK07 Cartridge Disks (VAX Only)

On VAX systems, the RK06 cartridge disk is a removable, random-access,bulk storage device with three data surfaces. The RK07 cartridge diskis a double-density RK06. The RK06 and RK07 are connected to the systemby an RK611 controller that interfaces to the UNIBUS adapter. Up toeight disk drives can be connected to each RK611.

2.1.16 RM03 and RM05 Pack Disks (VAX Only)

On VAX systems, the RM03 and RM05 pack disks are removable, moving-headdisks that consist of five data surfaces for the RM03 and 19 datasurfaces for the RM05. These disks are connected to the system by aMASSBUS adapter (MBA). Up to eight disk drives can be connected to eachMBA.

2.1.17 RP05 and RP06 Disk (VAX Only)

On VAX systems, the RP05 and RP06 removable disks consist of 19 datasurfaces and a moving read/write head. The RP06 removable disk hasapproximately twice the capacity of the RP05. These disks are connectedto the system by an MBA. Up to eight disk drives can be connected toeach MBA.

2.1.18 RP07 Fixed-Media Disk (VAX Only)

On VAX systems, the RP07 is a 516-MB, fixed-media disk drive thatattaches to the MASSBUS of the VAX-11/780 system. The RP07 transfersdata at 1.3 million bytes per second or as an option at a peak rate of2.2 million bytes per second. The nine platters rotate at 3600 rev/minand their data is accessed at an average speed of 31.3 ms. These disksare connected to the system by an MBA. Up to eight disk drives can beconnected to each MBA.

2.1.19 RRD40 and RRD50 Read-Only Memory (CD-ROM)

The RRD40 and RRD50 are compact disc read-only memory (CD-ROM) devicesthat use replicated media with a formatted capacity of approximately600 MB.

The RRD40 is a 5.25-inch half-height, front-loading tabletop orembedded device that attaches to the system using either the SmallComputer System Interface (SCSI) or Q-bus interface.

The RRD50 is a 5.25-inch, top-loading tabletop device that attaches tothe system using a Q-bus interface.

The RRD40 has an average access time of 0.5 second while the averageaccess time for the RRD50 is 1.5 seconds. Both the RRD40 and RRD50 havea data transfer rate of 150 KB per second.

The media for the RRD40 and the RRD50 are removable 4.7-inch (120-mm)compact discs. However, the media for the RRD40 are enclosed inprotective self-loading carriers. The RRD40 with a SCSI interface isalso available as an embedded unit. The RRD40 and RRD50 Q-bussubsystems are standard disk MSCP devices.

2.1.20 RX01 Console Disk (VAX Only)

On VAX systems, the RX01 disk uses a diskette. The disk is connected tothe LSI console on the VAX-11/780, which the driver accesses using theMTPR and MFPR privileged instructions.

For logical and virtual block I/O operations, data is accessed with oneblock resolution (four sectors). The sector numbers are interleaved toexpedite data transfers. Section 2.2.10 describes sector interleaving ingreater detail.

For physical block I/O operations, the track, sector, and cylinderparameters describe a physical, 128-byte RX01 sector (see Figure 2-1and Section 2.4). Note that the driver does not apply track-to-trackskew, cylinder offset, or sector interleaving to this physical mediumaddress.

Figure 2-1 Disk Physical Address

On VAX systems, the RX02 disk is a mass storage device that usesremovable diskettes. The RX02 supports existing single-density,RX01-compatible diskettes. A double-density mode allows diskettes to berecorded at twice the linear density. An entire diskette must beformatted in either single or double density. Mixed mode diskettes arenot allowed.

The RX02 is connected to the system by an RX211 controller thatinterfaces with the UNIBUS adapter. Up to two disk drives can becontrolled by each RX211.

For logical and virtual block I/O operations, data is accessed withsingle block resolution (four single-density sectors or twodouble-density sectors). The sector numbers are interleaved to expeditedata transfers. Section 2.2.10 describes this feature in greater detail.

For physical block I/O operations, the track and sector parametersshown in Figure 2-1 describe a physical sector (128 bytes in singledensity; 256 bytes in double density). The driver does not applytrack-to-track skew, cylinder offset, or sector interleaving to thephysical medium address.

2.1.22 RX23 (VAX Only)

On VAX systems, the RX23 device is a 1-inch high, flexible diskettedrive that uses 3.5-inch microfloppy diskettes. The RX23 drive canaccess standard- and high-density media. The following table summarizescapacities for standard- and high-density media:

The RX23 is backward compatible in that it can read 1-MB media. It canalso read and write 2.0-MB double-sided, high-density (135 tracks perinch) media.

The RX23 communicates with the controller using the ST506 fixed-diskinterconnect (FDI).

2.1.23 RX33 (VAX Only)

On VAX systems, the RX33 is a 1.2-MB, 5.25-inch, half-height diskettedrive. The RX33 can record in either standard- or high-density mode.High-density mode provides 1.2 MB of storage using 96 tracks per inchusing double-sided, high-density diskettes.

In standard-density mode, the RX33 drive is read- and write-compatiblewith single-sided, standard-density RX50 diskettes.

2.1.24 RX50 (VAX Only)

On VAX systems, the RX50 dual-diskette drive stores data infixed-length blocks on 5.25-inch 0.8-MB, flexible diskettes usingpreformatted headers. The RX50 can accommodate two diskettessimultaneously.

2.1.25 RZ22, RZ23, and RZ55 Disks

The RZ22 and RZ23 are 3.5-inch, half-height SCSI drives with an averageseek rate of 33 ms and an average data transfer rate of 1.25 MB persecond. The RZ22 and RZ23 have capacities of 52 MB and 104 MB,respectively.

The RZ55 is a 332-MB, 5.25-inch, full-height SCSI drive with an average access rate of 24 ms.

2.1.26 TU58 Magnetic Tape (DECtape II)

The TU58 is a random-access, mass storage magnetic tape device capableof reading and writing 256K bytes per drive of data onblock-addressable, preformatted cartridges at 800 bits per inch. Unlikeconventional magnetic tape systems, which store information at variablepositions on the tape, the TU58 stores information at fixed positionson the tape, as do magnetic disk or floppy disk devices. Therefore,blocks of data can be placed on tape in a random fashion, withoutdisturbing previously recorded data. In its physical geometry, the tapeis conceptually viewed as having one cylinder, four tracks percylinder, and 128 sectors per track. Each sector contains one 512-byteblock.

The TU58 uses two vectors. NUMVEC=2 is required on the CONNECT commandwhen specifying system parameters.

The TU58 interfaces with the UNIBUS adapter through a DL11-seriesinterface device. Both the TU58 and the DL11 should be set to 9600baud. (Because the TU58 is attached to a DL11, the user cannot directlyaccess the TU58 registers if the TU58 is on the UNIBUS.) The TU58,which has its own controller, can access either one or two tape drives.

2.2 Driver Features

Disk drivers provide the following features:

• Multiple controllers of the same type (except RB730), for example, more than one MBA or RK611 can be used on the system
• Multiple disk drives per controller (the exact number depends on the controller)
• Different types of disk drives on a single controller
• Static dual porting (MBA drives only)
• Overlapped seeks (except RL02, RX01, RX02, and TU58)
• Data checks on a per-request, per-file, or per-volume basis (except RX01 and RX02)
• Full recovery from power failure for online disk drives with volumes mounted
• Extensive error recovery algorithms, such as error code correction and offset (except RB02, RL02, RX01, RX02, and TU58); for DSA disks, these algorithms are implemented in the controller
• Dynamic, as well as static, bad block handling
• Logging of device errors in a file that can be displayed by field service personnel or customer personnel
• Online diagnostic support for drive level diagnostics
• Multiple-block, noncontiguous, virtual I/O operations at the driver level
• Logical-to-physical sector translation (RX01 and RX02 only)

The following sections describe these features in greater detail.

2.2.1 Dual-Pathed Disks

A dual-pathed disk is a dual-ported disk that isaccessible to all the CPUs in the cluster, not just to the CPUs thatare connected physically to the disk. Dual-pathed disks can be any ofthe following:

• Dual-ported MASSBUS disks
• Dual-ported HSC disks
• Dual-pathed DSA disks on local UDA50, KDA50, and KDB50 controllers
• Dual-ported RF-series disks

The term dual-pathed refers to the two paths through which clusteredCPUs can access a disk to which they are not directly connected. If onepath fails, the disk is accessed over the other path. (Note that with adual-ported MASSBUS disk, a CPU directly connected to the disk alwaysaccesses it locally.)

2.2.2 Dual Porting MASSBUS Disks

The MASSBUS disk drivers, DBDRIVER and DRDRIVER, support static dualporting. Dual porting allows two MASSBUS controllers to access the samedisk drive. Figure 2-2 shows this configuration. The RP05, RP06,RP07, RM03, RM05, and RM80 disk drives can be ordered, or upgraded inthe field, with the MASSBUS dual-port option.

Figure 2-2 Dual-Ported Disk Drives