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Measuring and Improving Drive Performance

section 5b. Measuring and Improving Drive Performance. This lesson includes the following sections: Average Access Time File Compression Data-Transfer Rate Optimizing Disk Performance Drive-Interface Standards. Average Access Time.

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Measuring and Improving Drive Performance

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  1. section 5b • Measuring and Improving Drive Performance

  2. This lesson includes the • following sections: • Average Access Time • File Compression • Data-Transfer Rate • Optimizing Disk Performance • Drive-Interface Standards

  3. Average Access Time • In storage devices, average access time (or seek time) is the time required for a read/write head to move to a spot on the storage medium. • For storage devices, access time is measured in milliseconds (ms), or thousandths of a second. In memory, access time is measured in nanoseconds (ns), or one-billionths of a second. • Diskette drives offer an average access time of 100 ms. Hard drives are faster, usually between 6 – 12 ms.

  4. Typical Access Times for Memory and Storage Devices

  5. Disk Specifications by Seagate

  6. My archive File Compression • File compression technology shrinks files so they take up less disk space. • Using a compression utility, you can shrink multiple files into a single archive file. • PKZIP, WinZip… • Utilities such as Windows' DriveSpace enable you to compress the entire contents of your hard disk.

  7. WinZip File Compression Utility

  8. Data-Transfer Rate • Data-transfer rate (or throughput) measures the time required for data to travel from one device to another. • If a device transfers 45,000 bytes per second, its data-transfer rate is 45 KBps. • Hard disks offer the fastest data-transfer rates of any storage device. • MBps v.s. Mbps • Megabytes per second • Megabits per second

  9. Optimizing Disk Performance • Cleaning Up Unneeded Files • Temporary files. • Used by Windows to store various versions of • documents in progress • Usually stored them with file-name • extension .tmp • You may use Windows built-in utility called Disk • Cleanup to remove them • Uninstalling

  10. Disk Cleanup Utility in Windows 2000

  11. Add/Remove Programs Utility in Windows 2000

  12. Optimizing Disk Performance (Cont.) • Scanning a Disk for Errors • Defragment a disk • Fragmentation occurs when a file is stored in pieces on different sectors on the disk’s surface

  13. Hard Disk Fragmentation One file can end up fragmented (scattered) over the disk surface.

  14. Hard Disk Fragmentation This results in multiple head accesses which degrades performance.

  15. Disk Scanning Utility in Windows 2000

  16. Disk Defragmenter Utility in Windows 2000

  17. Drive-Interface Standards • All PCs use a disk controller as an interface between a disk drive and the CPU. The two most common interface standards are EIDE and SCSI. • EIDE (Enhanced Integrated Drive Electronics) has evolved over the years and has several variants, all of which have different names (Fast IDE, ATA, Fast ATA, ATA-2, ATA-3, ATA-4, and Ultra ATA). • SCSI (Small Computer System Interface) is a faster, more flexible drive-interface standard found in high-performance computers.

  18. Section 5b Review • Define average access time and explain how it is measured. • Explain why file compression is a factor in drive performance. • Define data transfer rate and describe how it is measured. • Identify two drive interface standards.

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