Memory usage analysis (INFO memory) in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What command in Redis shows detailed memory usage information?

The INFO memory command displays detailed memory usage statistics in Redis.

beginner

What does the used_memory field represent in INFO memory output?

It shows the total number of bytes allocated by Redis for its own data structures and buffers.

intermediate

Explain the difference between used_memory and used_memory_rss in Redis memory info.

used_memory is the memory Redis uses internally, while used_memory_rss is the actual memory allocated by the operating system (Resident Set Size).

intermediate

What does mem_fragmentation_ratio indicate in Redis memory info?

It shows how much memory fragmentation exists. A value close to 1 means low fragmentation, higher values mean more wasted memory.

beginner

Why is monitoring total_system_memory important when analyzing Redis memory usage?

Because it helps understand Redis memory usage relative to the total system memory, which is important for avoiding out-of-memory issues.

Which Redis command provides memory usage details?

A INFO memory

B MEMORY USAGE

C GET memory

D SHOW MEMORY

The INFO memory command shows detailed memory statistics in Redis.

What does a mem_fragmentation_ratio greater than 1 indicate?

A Low memory fragmentation

B Redis is using less memory than allocated

C High memory fragmentation

D Redis is out of memory

A ratio above 1 means memory fragmentation is present, causing wasted memory.

What is the difference between used_memory and used_memory_rss?

A <code>used_memory</code> is OS memory, <code>used_memory_rss</code> is Redis internal memory

B <code>used_memory</code> is Redis internal memory, <code>used_memory_rss</code> is OS memory

C Both are the same

D They represent CPU usage

used_memory is Redis internal allocation; used_memory_rss is actual OS memory used.

Why should you monitor total_system_memory in Redis?

A To know Redis version

B To monitor CPU load

C To check network usage

D To avoid exceeding system memory limits

Knowing total system memory helps prevent Redis from causing out-of-memory errors.

Which field shows the peak memory Redis has used since start?

A used_memory_peak

B used_memory

C mem_fragmentation_ratio

D total_system_memory

used_memory_peak shows the highest memory usage Redis had since it started.

Describe the key memory metrics provided by the Redis INFO memory command and what they mean.

Think about internal memory, OS memory, peak usage, fragmentation, and system limits.

Explain why memory fragmentation matters in Redis and how you can identify it using INFO memory.

Focus on the fragmentation ratio and its effect.