- Using one
large disk:
- Using one
(very) large disk:
Results:
- The disk heads can
seeks (= moves) to
only 1 request location at
a time
- The disk can transfer data using only 1 transfer link
- The disk heads can
seeks (= moves) to
only 1 request location at
a time
- Using one
(very) large disk:
- Using many (smaller)
independent disks:
- Use multiple smaller disks
instead of
one large disk
Results:
- Different disks
can seek (= move) to
different request locations
Multiple independent disk heads can have one disk seeking to the next data block while another disk is transfering data
(I.e.: we can multi-task )
- Multiple disks can achive a shorter seek time delay by overlapping operations
- Multiple (independent) disk
have multiple data transfer links
- Multiple disks have higher total data transfer rate
- Different disks
can seek (= move) to
different request locations
- Use multiple smaller disks
instead of
one large disk
- Striping:
- Striping = storing the blocks of a file over multiple disks
Graphically:
- Reported experience:
- With
4 disks,
striping achieves an
average speed up of
3 times the speed of
1 (big) disk
(Assuming that the disk controller has a high enough transfer speed of 4 disks)
- With
4 disks,
striping achieves an
average speed up of
3 times the speed of
1 (big) disk