Sun Microsystems 96257 manual Data compression. See compression

control unit address. The base channel address to which a control unit can respond.

conversion. A process that changes the basic capability of a unit in a system and may be a disruptive, requiring a customer to turn over use of the unit to a CSE. Conver- sions may require special tools and higher-level skills of a technical specialist. Contrast with upgrade.

count-key data (CKD). A recording format that writes variable-length records. Contrast with fixed-block archi- tecture.

CPAT. Corporate Product Acceptance Testing. CPD. Central parts depot.

CPD. See controlled power-down.

CRC. See Customer Resource Center.

CRU. Customer-replaceable unit. Any item, module, or unit on a system that a customer can replace without as- sistance from a CSE.

CSA. Canadian Standards Association. A group serving industry, government, and consumers which develops product testing and certification standards and codes. The Canadian counterpart of Underwriters Laboratories.

CSE. See Customer Service Engineer.

CSL. Cartridge scratch loader; cartridge stacker/loader.

CSL. See Customer Services Logistics.

CSM. See Configuration Status Monitor.

CSR. Control Status Register.

CSRC. A Sun StorageTek internal tool managed by the NPDC that allows remote connection, operator panel ac- cess, and remote file download capability for virtual disk systems including VTSS.

CTR. Cache track recovery.

CTS. Corporate Technical Standard(s).

Customer Resource Center (CRC). A Sun StorageTek website (www.support.stortek.com) that provides re- sources including product documentation, tools and ser- vices, and customer training information.

Customer Service Engineer (CSE). A technical engi- neer who interacts with the end-user customers and is responsible for fixing product problems and maintaining product performance in customer accounts.

Customer Service Manager (CSM). A member of the Sun StorageTek management team with first-line techni- cal management responsibility for addressing problems in customer accounts.

Customer Services Logistics (CSL). An organization within Sun StorageTek responsible for coordinating deliv- ery of spare parts to field depots worldwide.

cyclic redundancy check (CRC). A check performed on data to see if an error has occurred in the transmit- ting, reading, or writing of data.

D

DAC. See disk array controller.

DACD. Disk array controller display. FRU designation for a VTSS local operator panel.

DASD. Direct-access storage device. (1) A storage de- vice (typically a magnetic disk) in which data access times are effectively independent of the location of the data on the device. Conversely, in a serial-access stor-

age device (e.g., a magnetic tape), data must be access- ed serially, such that data at the end of the tape spool take much longer to access than data on the tape which is passing immediately over the read/write head. (2) A device in which the media is always available to the read/write head without requiring mounting by an exter- nal agent.

data compression. See compression.

data striping. The process of writing large blocks of data across multiple drives and array groups to enhance data protection capabilities.

data transfer rate. The speed at which data can be transferred. Measured in bits per second (bps) for a mo- dem, and in megabytes per second (MBps) for a hard drive or fiber channel.

database. A collection of data arranged for ease and speed of retrieval.

dB. Decibel.

DBU. Disk buffer utilization. The ratio of used to total VTSS buffer capacity.

DC. Direct current. An electric current flowing in one di- rection only. Contrast with alternating current.

DCN. Document Change Notice. DDR. Defect discovery rate.

DDR. Dynamic device reconfiguration.

DDSR. Deleted Data Space Release. A VTSS ExPR software function that informs a controller when function- al volume datasets or minidisks are deleted, so that physical disk space occupied by deleted data can imme- diately become free space, thereby reducing DBU.

decibel (dB). In data transmission terms, a unit that measures the ratio of the difference in power between two electric signals.

decompress. To restore a compressed file to its original size.

dedicated connection. In an ESCD, a connection be- tween two ports that is not affected by information in link frames. A dedicated connection restricts the ports from communicating with other ports, and appears as one continuous link.

deinstallation. Physically disconnecting a subsystem with the intent of removing it from a customer site. Con- trast with relocation.

destage. In VSM, the non-synchronous write of new or updated data from cache or nonvolatile storage (NVS) to the VTSS disk arrays.

Detailed Manufacturing Instruction. A document con- taining a step-by-step description of the correct way to assemble an item, including illustrations if necessary.

device. A single physical HDA.

device reconstruction. A VTSS automatic background function that recreates and rewrites data from a failed device to a spare device using the functional track recov- ery (FTR) facility.

DFE. Distributed Fabric Element. DFT. Direct field transfer.

Diagnostic Manager (DMGR). In VTSS, a facility that administers, controls, and coordinates all diagnostic ac- tivity within the VTSS environment through the diagnos- tic submonitors (DSMs).

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