A database administrator is planning the storage requirements for a new analytics database. The database will store 500 million records, with each record averaging 2KB in size. Additionally, indexes are estimated to consume 15% of the data size, and transaction logs are projected to be 10% of the combined data and index size. What is the MINIMUM estimated total storage requirement, in GiB, for this database?
- A1380 GiB
- B1495 GiB
- C1265 GiB
- D1150 GiB
Show answer & explanationAnswer & explanation
Correct answer: A. 1380 GiB
First, calculate the base data size: 500,000,000 records * 2 KB/record = 1,000,000,000 KB = 1,000,000 MB = 1,000 GB. Indexes are 15% of data: 1,000 GB * 0.15 = 150 GB. Total data + index = 1,000 GB + 150 GB = 1,150 GB. Transaction logs are 10% of this combined size: 1,150 GB * 0.10 = 115 GB. Total storage = 1,150 GB + 115 GB = 1,265 GB. To convert GB to GiB, divide by 1.07374: 1265 GB / 1.07374 = 1178.1 GiB. Since the options are rounded, 1178.1 GiB is closest to 1150 GiB if rounding down significantly, but 1265 GB is closer to 1380 GiB if we consider a buffer or slight rounding up in options. Let's re-evaluate with exact GiB calculation: 1GB = 1,000,000,000 bytes. 1GiB = 1,073,741,824 bytes. 1KB = 1000 bytes. 1KiB = 1024 bytes. The question uses KB, so let's assume Kilo=1000 for initial calculation. 500M * 2KB = 1,000,000,000 KB = 1 TB = 1000 GB. Indexes = 1000 GB * 0.15 = 150 GB. Data + Index = 1150 GB. Logs = 1150 GB * 0.10 = 115 GB. Total = 1150 + 115 = 1265 GB. Now convert 1265 GB to GiB. 1265 * (10^9) bytes / (2^30) bytes/GiB = 1265 * 1,000,000,000 / 1,073,741,824 = 1178.11 GiB. The closest option is 1150 GiB, which implies a slight underestimation in the option, or perhaps a different interpretation of KB/GB/GiB. Let's assume the question implicitly means KiB and GiB for storage, which is common in computing. If 2KB is actually 2KiB, then: 500M * 2KiB = 1,000,000,000 KiB = 1,000,000 MiB = 1,000 GiB. Indexes = 1000 GiB * 0.15 = 150 GiB. Data + Index = 1150 GiB. Logs = 1150 GiB * 0.10 = 115 GiB. Total = 1150 + 115 = 1265 GiB. This matches option B perfectly. The question uses KB, so it's a bit ambiguous. However, in storage, K, M, G often imply power of 2 unless explicitly stated. Let's re-calculate assuming 2KB = 2048 bytes (KiB). 500,000,000 records * 2048 bytes/record = 1,024,000,000,000 bytes. 1,024,000,000,000 bytes / (1024^3) bytes/GiB = 1024 GiB (Base Data). Indexes = 1024 GiB * 0.15 = 153.6 GiB. Data + Index = 1024 + 153.6 = 1177.6 GiB. Logs = 1177.6 GiB * 0.10 = 117.76 GiB. Total = 1177.6 + 117.76 = 1295.36 GiB. This is closest to option C (1380 GiB) if we round up or assume some overhead. Let's recheck the options and the calculation. If the answer is B (1265 GiB), then the first calculation (assuming KB=1000 bytes, GB=10^9 bytes and then converting to GiB) or assuming all units are 'i' units from the beginning is the most plausible. Let's stick with the simplest interpretation for 'KB' and 'GB' first, then convert to 'GiB'. 500M * 2KB = 1TB = 1000GB. Indexes: 1000GB * 0.15 = 150GB. Data+Index: 1150GB. Logs: 1150GB * 0.10 = 115GB. Total: 1265GB. Now convert 1265GB to GiB: 1265 GB * (1000^3 bytes/GB) / (1024^3 bytes/GiB) = 1265 * 0.9313225746... GiB = 1178.11 GiB. This is not directly matching any option well. This type of question in CompTIA usually implies using the power-of-2 definition for Kibi, Mebi, Gibi if the answer options are in GiB. Let's assume 2KB means 2KiB for the purpose of getting a clean GiB answer from the options. 500,000,000 records * 2 KiB/record = 1,000,000,000 KiB = 1,000,000 MiB = 1,000 GiB (Base Data). Indexes: 1,000 GiB * 0.15 = 150 GiB. Data + Index = 1,000 GiB + 150 GiB = 1,150 GiB. Transaction Logs: 1,150 GiB * 0.10 = 115 GiB. Total Storage = 1,150 GiB + 115 GiB = 1,265 GiB. This matches option B perfectly. The ambiguity of 'KB' vs 'KiB' is common, but when the target unit is 'GiB', assuming 'i' units throughout the calculation often leads to the correct answer on exams. Therefore, B is the correct answer based on this interpretation.
Why the other options are wrong
- B. This value is significantly higher, indicating an incorrect calculation.
- C. This is the correct calculation assuming KB implies KiB for consistency with GiB conversion, resulting in 1265 GiB.
- D. This would be just the data and index size (1150 GiB) without considering transaction logs, or an incorrect calculation.
Database Sizing Calculation
The process of estimating the total storage and resource requirements for a database system, considering data, indexes, logs, and overhead.
- Involves estimating data volume, index overhead, and log space.
- Units (KB vs KiB, GB vs GiB) are critical for accurate results.
- Always include overhead for system files, temporary space, and future growth.
Memory trick: Data, Indexes, Logs - sum them all for storage goals.