Maxtor VL 17 manual Cache Management

Page 15

PRODUCTDESCRIPTION

Software ECC Correction

22 symbols, single burst, guaranteed

Automatic Park and Lock Operation

Immediately following power down, dynamic braking of the spinning disks delays momentarily allowing the read/write heads to move to an inner mechanical stop. A small fixed magnet holds the rotary actuator in place as the disk spins down. The rotary actuator is released only when power is again applied.

Cache Management

Buffer Segmentation

The data buffer is organized into two segments: the data buffer and the micro controller scratch pad. The data buffer is dynamically allocated for read and write data depending on the commands received. A variable number of read and write buffers may exist at the same time.

Read-Ahead Mode

Normally, this mode is active. Following a read request, disk read-ahead begins on the first sector and continues sequentially until the allocated buffer is full. If a read request is received during the read-ahead operation, the buffer is examined to determine if the request is in the cache. If a cache hit occurs, read- ahead mode continues without interruption and the host transfer begins immediately.

Automatic Write Reallocation (AWR)

This feature is part of the write cache and reduces the risk of data loss during deferred write operations. If a disk error occurs during the disk write process, the disk task stops and the suspect sector is reallocated to a pool of alternate sectors located at the end of the drive. Following reallocation, the disk write task continues until it is complete.

Write Cache Stacking

Normally, this mode is active. Write cache mode accepts the host write data into the buffer until the buffer is full or the host transfer is complete. A command complete interrupt is generated at the end of the transfer.

A disk write task begins to store the host data to disk. Host write commands continue to be accepted and data transferred to the buffer until either the write command stack is full or the data buffer is full. The drive may reorder write commands to optimize drive throughput.

2 – 4

Image 15

Contents HA RD Drive Produc T MA Nual DiamondMaxVL REV EC no Section Description Date U T I O N Before You BeginContents Handling and Installation Product SpecificationsHost Software Interface AT Interface DescriptionInterface Commands Service and SupportGlossary Figures Abbreviations IntroductionMaxtor Corporation Manual OrganizationNumbering Signal ConventionsConventions Key WordsProduct Description DiamondMax VL 17 Key FeaturesFunctional / Interface Product FeaturesOn-the-Fly Hardware Error Correction Code ECC Logical Block AddressingDefect Management Zone DMZ Cache Management Major HDA Components Dual Drive Support Subsystem ConfigurationJumper Location/Configuration Cylinder LimitationModels and Capacities Product SpecificationsDrive Configuration Performance SpecificationsParameter Standard Metric Physical DimensionsEnvironmental Limits Power RequirementsPower Mode Definitions EPA Energy Star ComplianceShock and Vibration Reliability SpecificationsSafety Regulatory Compliance Radiated Electromagnetic Field Emissions EMC ComplianceCanadian Emissions Statement Important Notice Handling and InstallationHard Drive Handling Precautions Pre-formatted DriveMulti-pack Shipping Container Unpacking and InspectionPhysical Installation Recommended Mounting ConfigurationRepacking Drive Identification Information Handling PrecautionsTools for Installation System RequirementsHard Drive Identification General RequirementsMounting Drive in System Systems Using Cable SelectInstalling 5.25-inch Mounting Brackets and Rails Installing in a Device BayAttaching System Cables Attaching Interface and Power CablesSystem Setup Setting the Bios CmosBios Cmos Parameters Hard Drive Preparation System Hangs During Boot Pin Description Summary Interface ConnectorPIN Signal AT Interface DescriptionPin Description Table PIN Name Signal Name Signal DescriptionPIO Timing Timing Parameters ModeDMA Timing Ultra DMA Timing Mode MIN MAXSustained Ultra DMA Data In Burst Device Terminating an Ultra DMA Data In Burst Initiating an Ultra DMA Data Out Burst Device Pausing an Ultra DMA Data Out Burst Device Terminating an Ultra DMA Data Out Burst Task File Registers Error RegisterFeatures Register Host Software InterfaceDevice/Head Register Sector Count RegisterSector Number Register Cylinder Number RegistersCommand Register Command Name Command Code Parameters Used Timer Value TIME-OUT PeriodSummary Digital Input Register Control Diagnostic RegistersAlternate Status Register Device Control RegisterReset and Interrupt Handling Reset HandlingInterrupt Handling Set Feature Commands Interface CommandsRead Commands Read SectorsRead Verify Sectors Read Multiple Read DMAWrite Verify Sectors Write CommandsSet Multiple Mode Write SectorsWrite DMA Write MultipleSet Feature Commands Set Features ModeValue Description Power Mode Commands Sleep Mode Initialization Commands Word Content DescriptionIdentify Drive 15-8 = PIO data transfer mode = Write Cache enabled Initialize Drive Parameters Format Track Seek, Format and Diagnostic CommandsExecute Drive Diagnostic Error Code DescriptionExecute S.M.A.R.T A.R.T. Command SetSupport Service and SupportService Policy No Quibble ServiceMaxFax Service Customer ServiceInternet Glossary Access TimeCylinder Zero Gigabyte GB Logical Block Addressing Read Gate Signal THIN-FILM Media