CompTIA Cloud Essentials+ (CLO-002)Management and Technical OperationsHard
A cloud service provider (CSP) offers a storage service with 99.999999999% (eleven nines) durability and 99.99% availability. A customer stores 100 TB of data in this service. If a single object is 1 MB, how many objects, on average, would the customer expect to lose over a year due to durability failures?
- A10 objects
- B100 objects
- C1,000 objects
- D1 object
Show answer & explanationAnswer & explanation
Correct answer: D. 1 object
First, calculate the total number of objects: 100 TB = 100 * 1024 GB = 102,400 GB = 102,400 * 1024 MB = 104,857,600 MB. So, 104,857,600 objects. Durability is 1 - (0.99999999999) = 0.00000000001 (10^-11). Expected loss = (Total Objects) * (1 - Durability) = 104,857,600 * 10^-11 ≈ 1.048 objects. Therefore, on average, 1 object would be lost.
Why the other options are wrong
- A. Incorrect calculation; significantly overestimates the loss.
- B. Incorrect calculation; significantly overestimates the loss.
- C. Incorrect calculation; significantly overestimates the loss.
Data Durability
The probability that a stored object will not be lost over a given period, typically expressed as 'nines' (e.g., 99.999999999%).
- Measures data loss prevention, not service uptime.
- Higher 'nines' indicate extremely low probability of data loss.
- Achieved through redundancy, replication, and error correction.
Memory trick: Durability is about loss, not uptime; calculate total objects, then multiply by the chance of a bust.