Question

Given a 1 TB Seagate ST 40000 M000 drive and its datasheet specifies a nonrecoverable readerror rate of 1 error per 10¹⁵ bits read. What can be an estimate of the probability of encountering an error if you read every sector on the disk once? (1 TB=10¹²B).

a. 0.08 errors per read of entire disk
b. 0.8 errors per read of entire disk
c. 0.0008 errors per read of entire disk
d. 0.008 errors per read of entire disk

Answer 1

Option D: To estimate the number of errors when reading a 1 TB disk with an error rate of 1 per 10^15 bits, calculate the total bits (8 * 10^12) and divide by the error rate, resulting in an expected 0.008 errors per read of the entire disk.

Step-by-step explanation:

To estimate the probability of encountering a nonrecoverable read error when reading every sector on a 1 TB Seagate ST 40000 M000 drive with a specified nonrecoverable read error rate of 1 error per 1015 bits read, we need to calculate the total number of bits on the disk and then apply the error rate to this number.

Firstly, 1 TB (terabyte) is equal to 1012 bytes. Each byte consists of 8 bits. So, a 1 TB drive contains 1012 bytes * 8 bits/byte = 8 * 1012 bits.

Given the error rate is 1 error per 1015 bits read, we can find the expected number of errors when the entire disk is read once by dividing the total number of bits by the error rate:

Expected errors = Total bits / Error rate = 8 * 1012 bits / 1015 bits/error = 8 * 10-3 errors per read of the entire disk.

This simplifies to 0.008 errors per read of the entire disk, which is answer choice (d).