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Memory and physical storage

Memory and physical storage. Unit objective: Identify memory characteristics and install storage devices. Topic A. Topic A: Memory Topic B: Storage devices. Memory. RAM: random access memory Working area for data during processing Need sufficient RAM for Performance Software support

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Memory and physical storage

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  1. Memory and physical storage Unit objective: Identify memory characteristics and install storage devices

  2. Topic A Topic A: Memory Topic B: Storage devices

  3. Memory • RAM: random access memory • Working area for data during processing • Need sufficient RAM for • Performance • Software support • Quality of RAM is important

  4. Measuring memory • Cells • Store a single bit of data • 0 or 1 • Represents on/off or yes/no • Measurement units • Bit • Nibble = 4 bits • Byte = 8 bits • Word = based on CPU • 32-bit processor: 32-bit word • 64-bit processor: 64-bit word

  5. Larger memory units • Byte (B) = 8 bits • Kilobyte (KB) = 1024 bytes = 210 bytes • Megabyte (MB) = 1024 KB = 220 bytes • Gigabyte (GB) = 1024 MB = 230 bytes • Terabyte (TB) = 1024 GB = 240 bytes

  6. Memory types • Classify memory as: • Volatile vs. non-volatile • Static vs. dynamic • Asynchronous vs. synchronous

  7. Volatile vs. non-volatile memory • Volatile: Loses contents without power • Non-volatile: Keeps contents without power

  8. Dynamic vs. static memory • Dynamic (DRAM) • Must be continually refreshed • Inexpensive • Physically small chips • Static (SRAM) • Refreshing not required • More expensive • Larger • Faster • Typical uses • Main system memory: DRAM • Cache memory and CMOS: SRAM

  9. Asynchronous vs. synchronous • Asynchronous • Not synchronized to system clock • Consistent time to access and read data • Synchronous • Synchronized to system clock • Accesses data and returns in one or more clock cycles • SDRAM faster than ADRAM

  10. Memory access types continued

  11. Memory access types, continued

  12. Access time • Latency • Memory speed • Nanoseconds vs. megahertz • Overall speed • Doesn’t include latency • Bandwidth

  13. Packaging • Early PCs used individual DRAM chips continued

  14. Packaging, continued • Package • Small circuit board • More commonly called a module • Installed in slot • Module contains • Memory chips • Connecting wires • Support chips • Pins or edge contacts

  15. Single- and double-sided modules • Early DRAM had chips on just one side • Double memory by placing chips on both sides • Double-sided modules have two rows of pins at bottom • Pins on front aren’t connected to pins on back • Number of chips no longer has a 1:1 chip-to-bit limit

  16. Package types • SIMM 30-pin – ADRAM • SIMM 72-pin – ADRAM • DIMM 100-pin – printer SDRAM • DIMM 168-pin – SDR SDRAM • DIMM 184-pin – DDR SDRAM • DIMM 240-pin • DDR2 • DDR3 continued

  17. Package types, continued • RIMM • 184-pin – 16-bit • 232-pin – 32--bit • MicroDIMM 144-pin • SODIMM 144-pin – SDR SDRAM • SODIMM 200-pin • DDR • DDR2 • SODIMM 204-pin – DDR3 SDRAM

  18. 30 pin SIMM

  19. 72 pin simm

  20. 168 pin dimm

  21. 184 pin ddr

  22. 240 pin ddr2

  23. Ddr and ddr2 difference

  24. 240 pin Ddr3

  25. RIMM

  26. sodimm

  27. Modules and chips • PC100 and PC133 use SDRAM • PC1600, PC2100, PC2700, and PC3200 use DDR SDRAM • PC2-3200, PC2-4200, PC2-5300, PC2-6400, and PC28500 use DDR2 SDRAM • PC3-6400, PC3-8500, PC3-10600, PC3-12800, PC3-14900, andPC-17000 use DDR3 SDRAM

  28. Memory error recovery • Parity — Detects an error • Even • Odd • Mark • Space • ECC — Detects and corrects an error • Desktop memory — No parity or ECC • Server memory — Often includes parity or ECC

  29. Parity 8 chips, no parity 9 chips, supportsparity

  30. Topic B Topic A: Memory Topic B: Storage devices

  31. CDs • Recordable CDs • CD drives • CD drive speeds

  32. DVDs • DVD media • DVD storage capacities

  33. Blu-Ray discs • Blu-Ray disc specifications • Recordable Blu-Ray

  34. Optical drive installation • Connectors • Drivers

  35. Using optical drives • CD software • Playing DVD and Blu-Ray discs

  36. Hard disk drives • Components • Solid-state drives (SSDs)

  37. Hard disk installation • Chassis • Cables and connectors • Power cable

  38. Fault tolerance • Ensure continued operations • RAID • RAID 0 • RAID 1 • RAID 5 • RAID 01 • RAID 10 • RAID considerations • Level-specific considerations

  39. RAID levels • RAID level 0 • Striping with no other redundancy features • RAID level 1 (Mirroring) • Simple disk mirroring continued

  40. RAID • Redundant Array of Independent Disks • Previously Inexpensive disks • RAID 1, 3 and 5 are most common • See http://www.acnc.com/raid

  41. RAID levels, continued • RAID level 1 – different type • Disk duplexing (simple disk mirroring again but each disk on a separate controller) continued

  42. RAID levels, continued • RAID level 2 (Stripping) • Data is striped across all disks in the array disk wear is limited and stripping allows for reconstruction if a drive fails

  43. RAID levels, continued • RAID level 3 (Disk Stripping) • Uses disk striping • Stores error-correcting information • Information written to only one disk in the array • If disk fails, array cannot rebuild its contents continued

  44. RAID levels, continued • RAID level 4 • Stripes data and stores error-correcting information on all drives • Can perform checksum verification • RAID level 5 • Combines the best features of RAID • Striping • Error correction • Checksum verification

  45. Windows OS software RAID does not support RAID 2 through to 4

  46. Choosing a RAID level • Boot and system files can be placed on disks configured for RAID level 1, but not for RAID level 5 • RAID level 1 uses two hard disks; RAID level 5 uses 3–32 disks • RAID level 1 is more expensive to implement than RAID level 5 • RAID level 5 requires more memory than RAID level 1

  47. Reading from disk is faster than write access in both RAID level 1 and RAID level 5 • RAID 5 has faster read access than RAID level 1

  48. Striped volume • Reduces the wear on multiple disk drives by equally spreading the load • Increases disk performance compared to other methods of configuring dynamic disk volumes

  49. Mirrored volume • Creates a copy of data on a backup disk • One of the most guaranteed forms of disk fault tolerance • Time to write information is doubled • If 3 or more volumes are mirrored or duplexed, RAID 1 is more expensive than other RAID levels • Can’t be striped • Requires two dynamic disks • Well suited when data is mission-critical

  50. RAID 5 • Provides better fault tolerance than a striped volume • Uses disk space more efficiently than a RAID 1 volume • RAID 5 with parity can reconstruct lost data on any disk • Requires minimum of three disks continued

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