English
Menu

System Architecture and Reliability

In a system with 500 GB of data in total, a full backup is taken every Sunday, and a differential backup is taken every night from Monday to Saturday. Each day, 20 GB of other data that had not been changed until then is changed. Which is the total size of the six differential backups from Monday to Saturday?

  1. A120 GB
  2. B420 GB
  3. C3,000 GB
Show answer and explanation

Answer: B. 420 GB

A differential backup contains all changes since Sunday's full backup, so each one grows: 20 GB on Monday, 40 GB on Tuesday, and so on, reaching 120 GB on Saturday. The total is 20 + 40 + 60 + 80 + 100 + 120 = 420 GB. With incremental backups each would be 20 GB, for a total of 120 GB, but a restore would need many backups applied in order. Taking a full backup every day would give 6 × 500 = 3,000 GB.

  • A. This is the total for incremental backups (20 GB × 6).
  • B. Correct. 20 + 40 + … + 120 = 420 GB.
  • C. This is the value for taking a full backup every day (500 GB × 6).
Practice this topic Back to topic

Related calculators

RAID Capacity CalculatorCalculate usable capacity, capacity efficiency, how many disk failures can be tolerated and the chance of data loss for RAID 0, 1, 5, 6 and 10 from the number and size of disksAvailability CalculatorCompute availability from MTBF and MTTR, and the availability and annual downtime of systems built from series, parallel and k-out-of-n units

Books on System Architecture and Reliability Ad

As an Amazon Associate I earn from qualifying purchases.

More System Architecture and Reliability questions

  1. In business continuity planning, which describes the RPO (recovery point objective)?
  2. For a system, the RPO (recovery point objective) is set at 4 hours and the RTO (recovery time objective) at 2 hours. A failure can occur at any time, and the time taken to make a backup is negligible. Which data protection scheme meets these targets?
  3. Database updates are replicated synchronously between two data centers 1,000 km apart. For each update, the system waits for one round trip: the transfer to the other site and the notification that the write is complete. Taking the speed of light in optical fiber as about 200,000 km/s and the fiber route length as equal to the straight-line distance, which is closest to the increase in the response time of one update caused by propagation alone?
  4. In an IaaS cloud service, which does the user generally manage?
  5. Among the ways to increase a system's processing capacity, which corresponds to scale-out?