Data Storage Strategies and RAID

Due Date:
9am 25th March 2019
Assignment Marks: 7% of unit
General Assignment Information:
This is the first of 4 quizzes that together add up to 30% of your grade for this
unit. You can do the quiz questions at any time until the due date and
answers should be submitted via the Turnitin link on blackboard.
CSG2132 – Enterprise Data
Data Storage Strategies and RAID

1. If a RAID 5 system is built using 5 disks with 2TB of
storage available per disk, the total available storage will
be _8_ TB
2. What filesystem technique is used to detect data
corruption of blocks?
Checksumming
3. Given the following data to be stored across four drives
in a RAID5 array, calculate the appropriate parity data.
Assume each stripe is one byte in length.
11110010 10001011 00111001
Rearrange Bytes
1 1 1 1 0 0 1 0
1 0 0 0 1 0 1 1
0 0 1 1 1 0 0 1
Parity 0 1 0 0 0 0 0 0
4. If the MTBF of a single disk is 1 million hours, and there
are 80 disks within a storage array, what is the average
number of disks that will fail within the first 2 years
(assuming a constant failure rate)?
MTBF (Array) = MTBF (Single) / Number Of Disks
= 1000000 / 80 = 12500 Hours
Average Number of Disks fail in 2 years = Hours in 2 years / 12500
= 1.36704
5. When are physical drives replaced in datacentre
environments? Why?
Data centres have two choices to replace disks, one when they
have already failed and need to be replaced. Second is
precautionary when some of the reads or writes to the disk start
failing, system speed of operation slows down as disk is not able to
perform optimum levels. This could also be gathered by looking at
statistical data aggregated from disk operations over a period of
time. These are called SMART parameters that can predict drive
failures and prompt for replacement.