part for questions.md

Rules Lec 3

• One platter = 2 surfaces

• Number of surfaces = number of tracks per cylinder = number of read/write heads in this disk = number of arms in this disk

• Number of Cylinders per disk = number of tracks per surface.

• Track Capacity = number of sectors per track * bytes per sector.

• Cylinder Capacity = number of tracks per cylinder * track capacity

• Platter Capacity = track capacity * number of tracks per surface * 2

• Surface Capacity = track capacity * number of tracks per surface

• Drive Capacity = number of cylinders per disk * cylinder capacity

• Number of sectors per track = track capacity / bytes per sector

• Number of sectors per cylinder = number of sectors per track * number of tracks per cylinder

• Number of sectors per surface = number of sectors per track * number of tracks per surface

• Number of sectors per platter = number of sectors per surface * 2

• Number of sectors per disk = number of sectors per track * number of tracks per surface * number of surfaces

• Number of tracks per platter = number of tracks per surface * 2

• Number of tracks per disk = number of tracks per surface * number per surfaces

• Number of records in sector = bytes of sector / bytes of record

• Number of records per cylinder = number of sectors per cylinder * number of records per sector

• Size of data subblock = blocking factor * record size

• Number of bytes in each block = size of data subblock + size of non-data overhead

• Transfer time = (Number of Bytes Transferred/ Number of Bytes on a Track) * Rotation Time

• Average Total time = average seek + average rotational delay + transfer time

Rules Lec 4

• b = physical length of data block = block size (bytes per block) / tape density (bytes of inch)

• g = length of an interblock gap

• number of inches required to store a block = b + g

• n = number of data block

• s = space requirement for storing the file = n * (b + g)

• Effective record density = number of bytes per block/number of inches required to store a block

• Normal Data Transmission Rate= Tape Density (bpi) * Tape Speed (ips)

• Effective Transmission Rate= (Effective Recording Density) * (Tape Speed)

Rules Lec 8

• b is the total number of blocks in the file.

• If the record is at the beginning of the file, then at least 1 block is accessed.

• If the record is at the end of the file, then at most b blocks are accessed.

• On average b/2

• time to find and read a record in a pile file is

  • Time to fetch one record = (b/2) * effective block transfer time

• Time for exhaustive reading of the file = seek time + rotational delay time + b * time to transfer one block -

• Time to read the last block = seek time + rotational delay time + block transfer time**

• Time to insert a new record = Time to read the last block + 2r

  • (2r - block transfer time): the time to wait for the disk until it rotates back to the original position.
  • (Block transfer time): the time to transfer the new record.

• Time to update a record for fixed length records = Time to fetch the record + 2r

• Time to update a record for variable length records = Time to delete the record + time to insert the new one

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Mina`s video

VID_20230530_155203_822.mp4

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Toqaa`s video

VID_20230531_231943_835.mp4