Update maxmemory and maxmemory-policy in Redis Server

terminal

No need of changing any thing in the .conf file just follow the following steps

Step 1: First check whether redis-server is working or not

$ redis-cli
127.0.0.1:6379> ping
PONG
if the reply is PONG then your server is working absolutely fine.

Step 2: To get the current max memory run the following commands:

$ redis-cli
127.0.0.1:6379> config get maxmemory
1) "maxmemory"
2) "0"
Initially it is set to 0 by default.

Step 3: After running the above step run the following commands to set the maxmemory:

127.0.0.1:6379> config set maxmemory 128M
OK
To check whether the maxmemory is set to 128M run step 2 again.

Step 4: Set maxmemory-policy 
127.0.0.1:6379> config set maxmemory-policy allkeys-lru

Step 6: After changing the maxmemory and maxmemory-policy exit Redis CLI
127.0.0.1:6379> exit

Step 6: Restart the redis-server

$ sudo systemctl restart redis
OR
$ sudo systemctl restart redis-server