13.1 through 13.5, 13.10 and 13.11

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47OChapter 13 Disk Storage, Basic File Structures, and HashingTable 13,1Specifications of Typical High-end Cheetah Disks from SeagateDescriptionModel NumberForm Factor (width)Form Factor (height)HeightWidthLengtl-rWeightCa pacity/ | nterfaceFormatted CapacityInterface TypeConfigurationNumber of disks (physical)Number of heads (physical)Number of CylindersTotal TracksBytes per SectorAreal DensityTrack DensityRecording Der-rsityBytes/Track (avg)PerformanceTransfer RatesInternal Transfer Rate (min)Internal Transfer Rate (max)Formated Int. Transfer Rate (rnin)Formated Int. Transfer Rate (max)External I/O Tiansfer Rate (ntax)Average Formatted Tiansfer RateSeek TimesAvg. Seek Time (Read)Avg. Seek Time (Write)Track-to-track, Seek, ReadTrack- to -track, Seek, WriteFull Disc Seek, ReadFull Disc Seek, WriteAvelage LatencyOtherDefault Buft'er {cae lre) sizeSpindle SpeedPower-on to Ready TineCheetah 10K.6sT3 I 46807LC3.5 inchI inch25.4 mm101.6 mm146.05 mm0.73 Kg146.8 Gbytes80-pin4849,85451236,000 Mb/sq.inch64,000 Tracks/inch570,000 bitsiinch475 Mbisec840 Mb/sec43 MB/sec78 MB/sec320 MB/sec59.9 MB/sec4.7 ms (typical)5.2 ms (typical)0.3 ms (typical)0.5 ms (typical)2.99 rns8,000 KB10000 RPMCheetah 10K.7sT3300007Lw3.5 inchI inch25.4 mm101.6 mnr146.05 mm0.726 kg300 Gbytes68-pin4890,774726,192512105,000 Tracks/inch658,000 bits/inch556472 Mblsec944 Mb/sec59 MB/sec118 MB/sec320 MB/sec59.5 MB/sec4.7 ms (typical)5.3 ms (typical)0.2 rr-rs (typical)0.5 ms (typical)9.,5 ms (tvpical)10.3 ms (typical)3 msec8,192 KB10000 RPM25 sec
13.2 Secondary Storage Devices 471Table 13.1 (continued)Specifications of Typical High-end Cheetah Disks from SeagateElectrical RequirementsCurrentTypical Current (12VDC +l- 5o/o)Typical Current (5VDC +l- 5o/o)Idle Power (typ)ReliabilityMean Time Between Failure (MTBF)Recoverable Read ErrorsNonrecoverable Read ErrorsSeek ErrorsService LifeLimited Warranty PeriodCheetah 'l 0K.60.95 amps0.9 amps10.6 watts1,200,000 Hours10 per 1012 bits10 per 1015 bitsl0 per 108 bits5 year(s)5 year(s)Cheetah 10K.71.09 amps0.68 amps10.14 watt1,400,000 Hoursl0 per l0l2 bits read10 per i015 bits read5 year(s)5 year(s)( Courtesy Seagate Tech nolog,v )block from disk is copied into the bufTer; whereas for a write command, the contentsof the buffer are copied into the disk block. Sometimes several contiguousblocks, called a cluster, may be transferred as a unit. In this case, the buffer size isadjusted to match the number of bytes in the cluster.The actual hardware mechanism that reads or writes a block is the disk read/writehead, which is part of a system called a disk drive. A disk or disk pack is mounted inthe disk drive, which includes .r motor that rotates the disks. A read/write headincludes an electronic component attached to a mechanical arm. Disk packs withmultiple surfaces are controlled by several read/write heads-one for each surface,as shown in Figure t3.l(b). All arms are connected to an actuator attached toanother electrical n-lotor, which moves the read/write heads in unison and positior-rsthem precisely over the cylinder of tracks specified in a block address.Disk drives for hard disks rotate the disk pack continuously at a constant speed(typically ranging between 5400 and 15,000 rpn-r). For a floppy disk, the disk drivebegins to rotate the disk whenever a particular read or rvrite request is initiated andceases rotation soon after the data trar-rsfer is completed. Once the read/write head ispositioned on the right track and the block specified in the block address movesunder the read/write head, the electronic component of the read/write head is activatedto transfer the data. Son-re disk units have fixed read/write heads, with as manyheads as there are tracks. These are called fixed-head disks, whereas disk units withan actuator are called movable-head disks. For fixed-head disks, a track or cylinderis selected by electronically switching to the appropriate read/write head rather thanby actual mechanical movement; cor.rsequently, it is much fhster. However, the costof the additional read/write heads is quite high, so fixed-head disks are not commonlyused.
Page 1 and 2: -\,--{+.nupt",. 1 3Disk StoragG, Ba
Page 3 and 4: 13.1 Introduction!( ) frl \.i()tl t
Page 5 and 6: 13.2 Secondarv Storaoe Devices467to
Page 7: 13.2 Secondary Storage Devicesi\ (r
Page 11 and 12: 13.3 Buffering of Blocks473r-e' and
Page 13 and 14: 13.4 Placinq File Records on Disk47
Page 15 and 16: 13.4 Placino File Records on Disk 4
Page 17 and 18: engtht."IIInumber of records per bl
Page 19 and 20: 13.5 Ooerations on Files481artment.
Page 21 and 22: I3.7 Files of Ordered Records (Sort
Page 23 and 24: 13.7 Files of Ordered Records (Sort
Page 25 and 26: 13.8 Hashino Techniouesn eachcbleme
Page 27 and 28: 13.8 Hashing TechniquesOther hashin
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Page 31 and 32: 'l 3.8 Hashing Techniquesute theNew
Page 33 and 34: 13.9 Other Primarv File Oroanizatio
Page 35 and 36: 13.10 Parallelizing Disk Access Usi
Page 37 and 38: 13. 10 Parallelizing Disk Access Us
Page 39 and 40: ,l|{l}'qn--*13.11 Storaoe Area Netw
Page 41 and 42: Review Ouestions. it has)ntoa'qulre

13.1 through 13.5, 13.10 and 13.11

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