ElastiCache slave-promote

Measurement script

#!/bin/bash

while :
do
  sleep 1
  date
  timeout 2 redis-cli -h <ElastiCache Primary Endpoint> set hoge h-imaoka
done

Result

#	score
1	10 sec
2	3 sec
3	10 sec
4	1 sec

Endpoint's ttl = 15 sec, so within it.
But this score does not contail chancel multi-AZ ops.

Why sentinel can not elect new master?

Erase /etc/redis-sentinel.conf part auto generated.
I pass it only sentinel.conf, it nothing to do with redis.conf .

What will happen - sentinel -

`save` at Master-node

Maybe failover happen

`bgsave` at Master-node

No failover

Can I use unpromoted slave (slave -> slave) as RO immediately?

No.

start A: Master, B: Slave, C: Slave
failover A: Failed , B: Master, C: Slave

Of cource, you can use B as a master immediately, but C is not. When failover, C state=wait_bgsave. In wait_bgsave, we can get key-values before failover happend time.
Untill C's state=online, can not get new key-values created after failover (write at new master B).

Restart master redis-daemon with RDB

No failover (@600MB memory size)
But slave status will be wait_bgsave

Restart master redis-daemon without RDB

No failover.
Just all data cleanup !

nutcracker

performance

redis-raw: 9,2k
nutcracker: 8.2k
elb : 7.1k

redis note