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1 William Stallings Computer Organization and Architecture Chapter 5 Memori External

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Page 1: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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William Stallings Computer Organization and ArchitectureChapter 5Memori External

Page 2: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Jenis Memori External

Magnetic DiskRAIDRemovable

OpticalCD-ROMCD-Writable (WORM)CD-R/WDVD

Magnetic Tape

Page 3: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Magnetic Disk

Metal atau plastic dilapisi dg material yg bersifat magnet (iron oxide)Jenis kemasan

FloppyWinchester hard diskRemovable hard disk

Page 4: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Format dan Organisasi Data

Lingkaran konsentris atau trackAda Gap antar trackGap sempit, kapasitas bertambahJumlah bit per track sama (kerapatan bervariasi)Kecepatan putar tetap

Track dibagi menjadi beberapa sectorUkuran minimum block adalah satu sectorSatu block bisa berisi lebih dari satu sector

Page 5: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Fixed/Movable Head Disk

Fixed headAda satu head (r/w) per trackHead diletakkan pada tangkai yg tetap

Movable headHanya ada satu head per sideDiletakkan pada tangkai yg dpt bergerak

Page 6: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Removable / Nonremovable

Removable diskDapat dilepas dari drive dan diganti dg disk lain Memberikan kapasitas simpanan yg tak terbatasMudah melakukan transfer data antar sistem

Nonremovable diskTerpasanang permanen dalam drive

Page 7: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Floppy Disk

8”, 5.25”, 3.5”Kapasitas kecil

sampai 1.44Mbyte (ada yg 2.88M)

LambatUmum dipakaiMurah

Page 8: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Winchester Hard Disk (1)

Dikembangkan oleh IBM di Winchester (USA)Dikemas dalam satu unitBerisi satu cakram atau lebihHead sangat kecilHandal

Page 9: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Winchester Hard Disk (2)

Umum digunakanMurahSbg external storage yg sangat cepatKapasitas semakin besar

Dalam orde GB

Page 10: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Removable Hard Disk

ZIPMurahBanyak digunakan100MB

JAZMahal1G

L-120 (a: drive)Juga dpt untuk membaca 3.5” floppy

Page 11: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Pencarian Sector

Harus dapat mengenali awal suatu track dan sectorFormat disk

Menambahkan informasi tambahanMemberi tanda awal track dan sector

Page 12: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Gap1 Id Gap2 Data Gap3 Gap1 Id Gap2 Data Gap3

TrackSyncByte Head Sector CRC Sync

ByteData CRC

ST506 format (old!)

Page 13: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Karakteristik

Fixed head atau movable headRemovable disk atau fixed diskSingle side atau double sideSingle platter atau multiple platterMekanisme head

Contact (Floppy)Fixed gapFlying (Winchester)

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Multiple Platter

Satu head per sideSemua head di-join dan di-alignTrack-track yg setiap platter membentuk cylinderData dipecah berdasarkan cylinder

Mengurangi gerakan headMeningkatkan kecepatan (transfer rate)

Page 15: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Kecepatan

Seek timegerakan head ke track yg dituju

(Rotational) latencyPutar platter sampai posisi data dibawah head

Access time = Seek + LatencyTransfer rate

Page 16: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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RAID

Redundant Array of Independent Disks Redundant Array of Inexpensive DisksAda 6 level Tidak berhirarkiSejumlah disks (fisik) yg dipandang sbg satu drive (logical) oleh Sistem OperasiData tersebar diantara disk fisik

Page 17: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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RAID 0

No redundancyData striped across all disksRound Robin stripingIncrease speed

Multiple data requests probably not on same diskDisks seek in parallelA set of data is likely to be striped across multiple disks

Page 18: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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RAID 1Mirrored DisksData is striped across disks2 copies of each stripe on separate disksRead from eitherWrite to bothRecovery is simple

Swap faulty disk & re-mirrorNo down time

Expensive

Page 19: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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RAID 2

Disks are synchronizedVery small stripes

Often single byte/word

Error correction calculated across corresponding bits on disksMultiple parity disks store Hamming code error correction in corresponding positionsLots of redundancy

ExpensiveNot used

Page 20: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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RAID 3

Similar to RAID 2Only one redundant disk, no matter how large the arraySimple parity bit for each set of corresponding bitsData on failed drive can be reconstructed from surviving data and parity infoVery high transfer rates

Page 21: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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RAID 4

Each disk operates independentlyGood for high I/O request rateLarge stripesBit by bit parity calculated across stripes on each diskParity stored on parity disk

Page 22: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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RAID 5

Like RAID 4Parity striped across all disksRound robin allocation for parity stripeAvoids RAID 4 bottleneck at parity diskCommonly used in network servers

N.B. DOES NOT MEAN 5 DISKS!!!!!

Page 23: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Optical Storage CD-ROM

Originally for audio650Mbytes giving over 70 minutes audioPolycarbonate coated with highly reflective coat, usually aluminumData stored as pitsRead by reflecting laserConstant packing densityConstant linear velocity

Page 24: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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CD-ROM Drive Speeds

Audio is single speedConstant linier velocity1.2 ms-1

Track (spiral) is 5.27km longGives 4391 seconds = 73.2 minutes

Other speeds are quoted as multiplese.g. 24xThe quoted figure is the maximum the drive can achieve

Page 25: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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00 00FF x 10 M

inSe

cSe

ctor

Mod

e

DataLayeredECC

12 byteSync

4 byteId

2048 byte 288 byte

2352 byte

CD-ROM Format

Mode 0=blank data fieldMode 1=2048 byte data+error correctionMode 2=2336 byte data

Page 26: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Random Access on CD-ROM

DifficultMove head to rough positionSet correct speedRead addressAdjust to required location(Yawn!)

Page 27: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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CD-ROM for & against

Large capacity (?)Easy to mass produceRemovableRobust

Expensive for small runsSlowRead only

Page 28: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Other Optical Storage

CD-WritableWORMNow affordableCompatible with CD-ROM drives

CD-RWErasableGetting cheaperMostly CD-ROM drive compatible

Page 29: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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DVD - what’s in a name?

Digital Video DiskUsed to indicate a player for movies⌧Only plays video disks

Digital Versatile DiskUsed to indicate a computer drive⌧Will read computer disks and play video disks

Dogs Veritable DinnerOfficially - nothing!!!

Page 30: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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DVD - technology

Multi-layerVery high capacity (4.7G per layer)Full length movie on single disk

Using MPEG compression

Finally standardized (honest!)Movies carry regional codingPlayers only play correct region filmsCan be “fixed”

Page 31: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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DVD - Writable

Loads of trouble with standardsFirst generation DVD drives may not read first generation DVD-W disksFirst generation DVD drives may not read CD-RW disksWait for it to settle down before buying!

Page 32: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Foreground Reading

Check out optical disk storage optionsCheck out Mini Disk

Page 33: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Magnetic Tape

Serial accessSlowVery cheapBackup and archive

Page 34: William Stallings Computer Organization and Architecture file`CD-ROM `CD-Writable (WORM) `CD-R/W `DVD. aMagnetic Tape. 3. ... aUkuran minimum block adalah satu sector ... Optical Storage

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Digital Audio Tape (DAT)

Uses rotating head (like video)High capacity on small tape

4Gbyte uncompressed8Gbyte compressed

Backup of PC/network servers