English
Menu

System Architecture and Reliability

A full backup is taken every Sunday night, and an incremental backup is taken every night from Monday to Saturday. A failure occurs at midday on Thursday, and it is decided to restore the data to the point of Wednesday night's backup. Which is the number of backups used for the restore?

  1. A2
  2. B3
  3. C4
Show answer and explanation

Answer: C. 4

An incremental backup contains only the changes since the previous backup, so after restoring Sunday's full backup, the incremental backups of Monday, Tuesday and Wednesday must be applied in order. The number of backups used is therefore 1 + 3 = 4. Two would be enough if differential backups were taken every night (the full backup and Wednesday's differential backup).

  • A. This is the number for differential backups. With incremental backups, every intermediate incremental is needed too.
  • B. This counts only the three incremental backups and leaves out Sunday's full backup on which they are based.
  • C. Correct. One full backup and the three incremental backups from Monday to Wednesday.
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 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?
  2. In business continuity planning, which describes the RPO (recovery point objective)?
  3. 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?
  4. 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?
  5. In an IaaS cloud service, which does the user generally manage?