Master Redis Monitoring: Key Metrics, Commands, and Performance Tips

Monitoring Metrics

Performance

Memory

Basic activity

Persistence

Error

Memory Metrics

Name

Description

used_memory

Used memory

mem_fragmentation_ratio

Memory fragmentation ratio

evicted_keys

Number of keys evicted due to maxmemory limit

blocked_clients

Clients blocked by BLPOP, BRPOP, or BRPOPLPUSH

Basic Activity Metrics

Name

Description

connected_clients

Number of client connections

connected_slaves

Number of slave connections

master_last_io_seconds_ago

Seconds since last master‑slave interaction

keyspace

Total number of keys in the database

Persistence Metrics

Name

Description

rdb_last_save_time

Timestamp of the last RDB persistence to disk

rdb_changes_since_last_save

Number of changes since the last persistence

Error Metrics

Name

Description

rejected_connections

Connections rejected because maxclients limit was reached

keyspace_misses

Number of key look‑ups that missed (no hit)

master_link_down_since_seconds

Duration (seconds) of master‑slave disconnection

Monitoring Methods

redis-benchmark

redis-stat

redis-faina

redislive

redis-cli

monitor

showlog

get (slow‑query log)

len (slow‑query log entry count)

reset (reset slow‑query log)

Relevant Configuration

slowlog-log-slower-than 1000   # set slow‑query threshold in microseconds
slowlog-max-len 100           # set length of slow‑query log (number of commands)

Info Command Usage

info (retrieve all information or specific sections)

server: server environment parameters

clients: client‑related information

memory: memory statistics

persistence: persistence information

stats: general statistics

replication: master‑slave replication details

cpu: CPU usage

cluster: cluster information

keyspace: key‑value statistics

Performance Monitoring Example

redis-cli info | grep ops   # operations per second

Memory Monitoring Example

# used_memory_human: 2.99M  # total memory allocated by allocator
# used_memory_rss_human: 8.04M  # memory seen by OS (top)
# used_memory_peak_human: 7.77M  # peak memory consumption
# used_memory_lua_human: 37.00K  # memory used by Lua engine

Redis Performance Test Command

./redis-benchmark -c 100 -n 5000   # 100 connections, 5000 requests