primary index is dense index

In a B+tree, all pointers to data records exists at the leaf-level nodes

Reading or writing a disk block is time consuming because of the seek time

Collisions occur when a new record hashes to a bucket that is already fuill

uses mirrored disks

the program checks the subsequent positions in order until an unused (empty) position is found,

If record size R=2 kbytes

block size B=4096 bytes r=12288 records, The number of file blocks is

Preferred secondary storage device for low storage capacity and high cost.

Data stored as magnetized areas on magnetic disk surfaces

Data stored contains several magnetic disks connected to a rotating spindle.

Disks are divided into concentric circular tracks on each disk surface.

Track capacities vary typically from 4 to 50 bytes or more

A sectors is divided into smaller blocks or track

The division of a track into sectors is hard-coded on the disk surface and can be changed.

A track is divided into blocks.

The block size B is Variable for each system.

Typical block sizes range from B=512 bytes to B=4096 bytes

Whole blocks are transferred between disk and disk blocking for processing

A read-write head moves to the track that contains the block to be transferred.