Understanding File System Performance: Key Scenarios Explained Quiz

Explore fundamental file system performance concepts with practical interview-style questions about caching, latency, throughput, fragmentation, and more. Assess how typical file operations impact system efficiency and resource usage.

1. Impact of File Fragmentation

   Which of the following most likely results from severe file fragmentation on a traditional spinning hard drive?

   1. Improved sequential throughput
   2. Higher CPU temperature
   3. Increased disk read times
   4. Lower network latency

   Explanation: Severe file fragmentation causes a file to be stored in non-contiguous blocks, leading to increased read times as the disk head must move frequently. CPU temperature is unrelated, network latency concerns network traffic not disk access, and sequential throughput is usually reduced by fragmentation, not improved.

2. Effectiveness of File System Caching

   What is the primary reason file systems use caching for frequently accessed files?

   1. To expand physical storage capacity
   2. To increase file security
   3. To enforce file permissions
   4. To reduce disk I/O latency

   Explanation: Caching puts frequently accessed data in faster memory, reducing the need to fetch data from slower disk and thus lowering I/O latency. Caching does not increase total storage, nor does it provide extra security or directly enforce permissions.

3. Sequential vs. Random Access Performance

   Why does sequential file access typically outperform random file access on spinning hard drives?

   1. File sizes become smaller
   2. CPU usage drops to zero
   3. Fewer seek operations are required
   4. Files are always stored in RAM

   Explanation: Sequential access means data is read in order, minimizing mechanical movement of the disk head and seek time. Accessing files does not change their size or ensure RAM storage, and CPU is still used during read operations.

4. Write Buffering and Data Integrity

   When a system uses write buffering, what potential risk arises if power is suddenly lost before the buffer is flushed?

   1. Improved write throughput
   2. Faster completion of writes
   3. Automatic backup creation
   4. Data loss or corruption

   Explanation: Unflushed write buffers can result in data that never reaches disk, causing data loss or corruption. While buffering may speed up writes, sudden loss does not benefit throughput, nor does it trigger backups.

5. Role of Block Size in File System Performance

   How does a very large file system block size most likely affect storage efficiency for many small files?

   1. It increases wasted space due to internal fragmentation
   2. It eliminates the need for directories
   3. It boosts CPU performance
   4. It reduces disk seek time

   Explanation: Large block sizes typically lead to wasted space when storing small files, as each file occupies at least one block even if not fully used. Large block sizes do not remove directories, do not impact CPU speed directly, and disk seek times are more about physical disk characteristics.

6. Access Patterns and Throughput

   If a workload mostly reads large sequential files, which file system characteristic is most important for performance?

   1. Frequent inode updates
   2. High sustained read throughput
   3. Small block size
   4. Complex metadata indexing

   Explanation: Large sequential reads benefit most from high sustained throughput. Small block sizes and complex indexing are more helpful for random access. Inode updates are more related to frequent file creation or deletion.

7. Memory Usage in File Systems

   What may happen if a server's file system cache uses most available RAM?

   1. Read and write latency always increases
   2. Disk health deteriorates
   3. File fragmentation will increase
   4. Overall system performance can degrade

   Explanation: Excessive caching can cause memory shortage for other processes, slowing down the system. File fragmentation is unrelated, and increased cache should lower latency. Disk health is not directly impacted by cache use.

8. Network File Systems and Latency

   When using a network-based file system, which factor most commonly causes higher read and write latency compared to local disk?

   1. Directory recursion depth
   2. Physical disk spin speed
   3. Network transmission delay
   4. Clustered file names

   Explanation: Network file systems introduce transmission delays not present in local disk access. Spin speed is relevant for physical disks only, while clustered names and directory depth have much less impact on overall latency in this scenario.

9. Journaling and File Consistency

   What is the main benefit of a journaling file system after a system crash?

   1. Quicker application launching
   2. Faster and safer recovery of file system state
   3. Higher file compression ratios
   4. Lower hardware failure rates

   Explanation: Journaling allows file systems to recover more quickly and safely after crashes by recording changes. It does not affect compression, application startup, or reduce hardware failure rates.

10. Bottleneck Identification in File Performance

    If file operations are slow but disk activity light, which system resource should next be checked for causing the bottleneck?

    1. CPU utilization
    2. File handle count
    3. Disk block size
    4. Disk platter speed

    Explanation: When the disk is underused but operations are slow, CPU utilization may reveal processing delays or heavy background tasks. Disk speed, block size, and handle count are more relevant if the disk itself is the limiting factor.