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This chapter delves into the intricacies of disk storage and I/O connections in computer architecture. Covering essential concepts such as non-volatile storage, magnetic disk structures, RAID configurations, and various I/O bus types, it provides insights into the operational metrics like rotational latency and data transfer rates. The section also highlights the differences between traditional hard disks and solid-state drives (SSD), discussing performance implications, cost factors, and durability considerations. It aims to equip readers with a foundational understanding of efficient data management in computing systems.
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Chapter 6: 22540 - Computer Arch. & Org. (2) Disk Storage
I/O Connection Interrupts Processor Cache Memory I/O Interconnect MainMemory I/OController I/OController I/OController I/ODevices Network Disk Disk
Magnetic Disk • Nonvolatile • Tracks & Sectors • Recorded Information • Sector Number, Gap, Data, ECC, Gap, Next Sector Num. • Rotational Latency • 5400 RPM (½ rotation / 5400) = 5.6 ms • Transfer Time • Sector: ≈ 100 MB/s • Cache: ≈ 375 MB/s = 3 Gbps SATA-2
Disk Interface • Advanced Technology Attachment • SATA (Serial) • Small Computer Systems Interface • SCSI (Parallel) • SAS (Serial Attached SCSI)
Flash Storage • Semiconductor • Non Volatile (EEPROM) • Faster, Smaller and Lower Power • Higher Cost • Block R/W • Wearout (10,000 ~ 100,000 Writes per Cell) • Wear Leveling (Remap Blocks) • Solid State Disk (SSD) • Hybrid Hard Disk
Busses • Processor-Memory Bus • Short, High Speed and Matched Width • I/O Bus • Can be Lengthy and Connect Many Types • Often Have a Wide Range Bandwidth
I/O Transaction • Two Parts • Sending Memory Address • Sending or Receiving Data • Synchronous • All Devices on the Bus Run on the Same Clock Rate • Clock Skew Limits Length • Asynchronous • External: Firewire, USB, etc. • Internal: PCI Express, SATA, etc. • Handshaking
Parallelism & I/O • Redundant Array of Inexpensive Disks (RAID) • RAID 0 Striping BLK 0 BLK 2 BLK 4 BLK 6 BLK 1 BLK 3 BLK 5 BLK 7
Parallelism & I/O • Redundant Array of Inexpensive Disks (RAID) • RAID 0 Striping • RAID 1 Mirroring BLK 0 BLK 1 BLK 2 BLK 3 BLK 0 BLK 1 BLK 2 BLK 3
Parallelism & I/O • Redundant Array of Inexpensive Disks (RAID) • RAID 0 Striping • RAID 1 Mirroring • RAID 2 Error Detection & Correction Code Bit 0 Bit 2 Bit 4 Bit 6 Bit 1 Bit 3 Bit 5 Bit 7 Parity Parity Parity Parity
Parallelism & I/O • Redundant Array of Inexpensive Disks (RAID) • RAID 0 Striping • RAID 1 Mirroring • RAID 2 Error Detection & Correction Code • RAID 3 Bit-Interleaved Parity Byte 0 Byte 2 Byte 4 Byte 6 Byte 1 Byte 3 Byte 5 Byte 7 Parity Parity Parity Parity
Parallelism & I/O • Redundant Array of Inexpensive Disks (RAID) • RAID 0 Striping • RAID 1 Mirroring • RAID 2 Error Detection & Correction Code • RAID 3 Bit-Interleaved Parity • RAID 4 Block-Interleaved Parity BLK 0 BLK 2 BLK 4 BLK 6 BLK 1 BLK 3 BLK 5 BLK 7 Parity Parity Parity Parity
Parallelism & I/O • Redundant Array of Inexpensive Disks (RAID) • RAID 0 Striping • RAID 1 Mirroring • RAID 2 Error Detection & Correction Code • RAID 3 Bit-Interleaved Parity • RAID 4 Block-InterleavedParity • RAID 5 Distributed Block- Interleaved Parity BLK 0 BLK 2 Parity BLK 6 BLK 1 Parity BLK 4 BLK 7 Parity BLK 3 BLK 5 Parity
Chapter 6 The End