Information Technology Reference
In-Depth Information
Size
Form factor
2.5-inch
Capacity
320 GB
Performance
Spindle speed
5400 RPM
Average seek time
12.0 ms
Maximum seek time
21 ms
Track-to-track seek time
2 ms
Transfer rate (surface to buffer)
850 Mbit/s (maximum)
Transfer rate (buffer to host)
3 Gbit/s
Buer memory
8 MB
Figure12.9: Hardware specifications for a 320GB SATA disk drive.
3. For the disk in Figure 12.3 on page 360, estimate the distance from the
center of one track to the center of the next track.
4. A disk may have multiple surfaces, arms, and heads, but when you issue
a read or write, only one head is active at a time. It seems like one could
greatly increase disk bandwidth for large requests by reading or writing
with all of the heads at the same time. Given the physical characteristics
of disks, can you figure out why no one does this?
5. For the disk described in Figure 12.3 on page 360, consider a workload
consisting of 500 read requests, each of a randomly chosen sector on disk,
assuming that the disk head is on the outside track and that requests are
serviced in P-CSCAN order from outside to inside. How long will servicing
these requests take?
Note: Answering this question will require making some estimates.
6. Suppose I have a disk such as the 320GB SATA drive described in Fig-
ure 12.9 on page 381 and I have a workload consisting of 10000 reads to
sectors randomly scattered across the disk. How long will these 10000
request take (total) assuming the disk services requests in FIFO order?
7. Suppose I have a disk such as the 320GB SATA drive described in Fig-
ure 12.9 on page 381 and I have a workload consisting of 10000 reads to
10000 sequential sectors on the outer-most tracks of the disk. How long
will these 10000 request take (total) assuming the disk services requests
in FIFO order?
8. Suppose I have a disk such as the 320GB SATA drive described in Fig-
ure 12.9 on page 381 and I have a workload consisting of 10000 reads to
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