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Computer Organization and Architecture

Computer Organization and Architecture. Chapter 5 Memori External. Jenis Memori External. Magnetic Disk RAID Removable Optical CD-ROM CD-Writable (WORM) CD-R/W DVD Magnetic Tape. Magnetic Disk. Metal atau plastic dilapisi dg material yg bersifat magnet (iron oxide) Jenis kemasan

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Computer Organization and Architecture

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  1. Computer Organization and Architecture Chapter 5 Memori External Materi ke 5 Memory External by kustanto

  2. Jenis Memori External • Magnetic Disk • RAID • Removable • Optical • CD-ROM • CD-Writable (WORM) • CD-R/W • DVD • Magnetic Tape Materi ke 5 Memory External by kustanto

  3. Magnetic Disk • Metal atau plastic dilapisi dg material yg bersifat magnet (iron oxide) • Jenis kemasan • Floppy • Winchester hard disk • Removable hard disk Materi ke 5 Memory External by kustanto

  4. Format dan Organisasi Data • Lingkaran konsentris atau track • Ada Gap antar track • Gap sempit, kapasitas bertambah • Jumlah bit per track sama (kerapatan bervariasi) • Kecepatan putar tetap • Track dibagi menjadi beberapa sector • Ukuran minimum block adalah satu sector • Satu block bisa berisi lebih dari satu sector Materi ke 5 Memory External by kustanto

  5. Fixed/Movable Head Disk • Fixed head • Ada satu head (r/w) per track • Head diletakkan pada tangkai yg tetap • Movable head • Hanya ada satu head per side • Diletakkan pada tangkai yg dpt bergerak Materi ke 5 Memory External by kustanto

  6. External Memory Removable / Nonremovable • Removable disk • Dapat dilepas dari drive dan diganti dg disk lain • Memberikan kapasitas simpanan yg tak terbatas • Mudah melakukan transfer data antar sistem • Nonremovable disk • Terpasanang permanen dalam drive Materi ke 5 Memory External by kustanto

  7. Floppy Disk • 8”, 5.25”, 3.5” • Kapasitas kecil • sampai 1.44Mbyte (ada yg 2.88M) • Lambat • Umum dipakai • Murah Materi ke 5 Memory External by kustanto

  8. Winchester Hard Disk (1) • Dikembangkan oleh IBM di Winchester (USA) • Dikemas dalam satu unit • Berisi satu cakram atau lebih • Head sangat kecil • Handal Materi ke 5 Memory External by kustanto

  9. Winchester Hard Disk (2) • Umum digunakan • Murah • Sbg external storage yg sangat cepat • Kapasitas semakin besar • Dalam orde GB Materi ke 5 Memory External by kustanto

  10. ORGANISASI DISK MAGNETIK

  11. Pencarian Sector • Harus dapat mengenali awal suatu track dan sector • Format disk • Menambahkan informasi tambahan • Memberi tanda awal track dan sector Materi ke 5 Memory External by kustanto

  12. ST506 format (old!) Gap1 Gap1 Id Gap2 Data Gap3 Id Gap2 Data Gap3 Sync Byte Track Sync Byte Head Sector CRC Data CRC CRC (Cyclical Redundancy Check), digunakan untuk memverifikasi data yang error akibat gangguan jaringan, distorsi, Pesan error ini biasanya terjadi ketika PC atau laptop mencoba untuk membaca data dari media penyimpanan yang rusak, seperti hard disk, CD, atau DVD Materi ke 5 Memory External by kustanto

  13. Karakteristik • Fixed head atau movable head • Removable disk atau fixed disk • Single side atau double side • Single platter atau multiple platter • Mekanisme head • Contact (Floppy) • Fixed gap • Flying (Winchester) Materi ke 5 Memory External by kustanto

  14. Multiple Platter • Satu head per side • Semua head di-join dan di-align • Track-track yg setiap platter membentuk cylinder • Data dibagi berdasarkan cylinder • Mengurangi gerakan head • Meningkatkan kecepatan (transfer rate) Materi ke 5 Memory External by kustanto

  15. Kecepatan • Pencarian waktu (Seek time) • gerakan head ke track yg dituju • (Rotational) latency • Putar platter sampai posisi data dibawah head • Access time = Seek + Latency • Transfer rate Materi ke 5 Memory External by kustanto

  16. RAID (Redundant Array of Independent Disks) • Ada 6 level • Tidak berhirarki • Sejumlah disks (fisik) yg dipandang sbg satu drive (logical) oleh Sistem Operasi • Data tersebar diantara disk fisik Materi ke 5 Memory External by kustanto

  17. RAID 0 • No redundancy • Data striped across all disks • Bergaris bulat (Round Robin striping) • Meningkatkan kecepatan (Increase speed) • Multiple data requests probably not on same disk • Disks seek in parallel • A set of data is likely to be striped across multiple disks Materi ke 5 Memory External by kustanto

  18. RAID 1 • Mirrored Disks • Data is striped across disks • 2 copies of each stripe on separate disks • Read from either (baik) • Write to both • Recovery is simple • Swap faulty disk & re-mirror • No down time • Expensive Materi ke 5 Memory External by kustanto

  19. RAID 2 • Disks are synchronized • Error correction calculated across corresponding bits on disks • Multiple (beberapa) parity disks store Hamming code error correction in corresponding positions • Lots of redundancy • Expensive • Not used Materi ke 5 Memory External by kustanto

  20. RAID 3 • mirip (Similar) to RAID 2 • Hanya 1 disk yang berlebihan, tanpa memperdulikan seberapa besar arraynya (Only one redundant disk, no matter how large the array) • Sederhana paritas bitnya untuk setiap bit yang sama (Simple parity bit for each set of corresponding bits) • Data on failed drive can be reconstructed from surviving data and parity info • Very high transfer rates Materi ke 5 Memory External by kustanto

  21. RAID 4 • Each disk operates independently • Tingkat permintaan I/O baik (Good for high I/O request rate) • Garisnya besar (Large stripes) • Bit by bit parity calculated across stripes on each disk • Penyimpanannya di atas parity disk (Parity stored on parity disk) Materi ke 5 Memory External by kustanto

  22. RAID 5 • Like RAID 4 • Bergaris di semua disk paritas (Parity striped across all disks) • Round robin allocation for parity stripe • Menghindari kemacetan RAID 4 pada parity disk (Avoids RAID 4 bottleneck at parity disk) • Umumnya untuk server (Commonly used in network servers) • N.B. DOES NOT MEAN 5 DISKS!!!!! Materi ke 5 Memory External by kustanto

  23. Optical Storage CD-ROM • Originally for audio • 650Mbytes giving over 70 minutes audio • Biasanya Dilapisi almunium (Polycarbonate coated with highly reflective coat, usually aluminum) • Data stored as pits • Read by reflecting laser • Kepadatan packing konstan (Constant packing density) • Constant linear velocity (kecepatan linear konstan) Materi ke 5 Memory External by kustanto

  24. CD-ROM Drive Speeds • Audio is single speed • Kecepatan konstan (Constant linier velocity) • 1.2 ms-1 • Track (spiral) is 5.27km long • Gives 4391 seconds = 73.2 minutes • Kecepatan lainnya adalah kelipatannya (Other speeds are quoted as multiples) • e.g. 24x • Angka kecepatan max dapat dicapai (The quoted figure is the maximum the drive can achieve) Materi ke 5 Memory External by kustanto

  25. CD-ROM Format • Mode 0=blank data field • Mode 1=2048 byte data+error correction • Mode 2=2336 byte data Layered ECC 00 FF x 10 00 Mode Data Sec Sector Min 12 byte Sync 4 byte Id 2048 byte 288 byte 2352 byte Materi ke 5 Memory External by kustanto

  26. Random Access on CD-ROM • Berat (Difficult) • Perpindahan head kasar (Move head to rough position) • Set correct speed • Read address • Memerlukan lokasi (Adjust to required location) Materi ke 5 Memory External by kustanto

  27. CD-ROM for & against • Large capacity (?) • Mudah diproduksi masal (Easy to mass produce) • Removable • Robust or strong • Expensive for small runs • Lambat (Slow) • Read only Materi ke 5 Memory External by kustanto

  28. Other Optical Storage • CD-Writable • WORM • Terjangkau (Now affordable) • Compatible with CD-ROM drives • CD-RW • Dapat dihapus (Erasable) • semakin murah (Getting cheaper ) • Sebagian besar kompatibel (Mostly CD-ROM drive compatible) Materi ke 5 Memory External by kustanto

  29. DVD - what’s in a name? • Digital Video Disk • Used to indicate a player for movies • Only plays video disks • Digital Versatile Disk • Used to indicate a computer drive • Will read computer disks and play video disks Materi ke 5 Memory External by kustanto

  30. DVD - technology • Multi-layer • Very high capacity (4.7G per layer) • Full length movie (film) on single disk • Using MPEG compression • Finally standardized (honest!) • Movies carry regional (daerah) coding • Players only play correct region films • Can be “fixed” Materi ke 5 Memory External by kustanto

  31. Magnetic Tape • Serial access • Lambat (Slow) • Very cheap • Backup and archive Materi ke 5 Memory External by kustanto

  32. Digital Audio Tape (DAT) • Uses rotating head (like video) • High capacity on small tape • 4Gbyte uncompressed • 8Gbyte compressed • Backup of PC/network servers Materi ke 5 Memory External by kustanto

  33. End of Session Memory External Materi ke 3

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