Check_redis_procs : This is used to monitor Redis service running status means it is running or stop. This command will continuously ping redis port and check its working or not.
Check_redis_mem : Number of bytes that Redis allocated as seen by the operating system means how much memory or ram is allocated by redis service and how much is remaining on the server. Here in warning and critical provide value as per your requirement.
Check_redis_clients : this command will check how many no. of clients connected on redis sever. The threshold value for warning and critical I used here 1000 and 1500 clients you can use as per your requirement.
Note : You can also monitor multiple parameters from Redis service. Above three are most important parameters to monitor.
To check some other parameters with their threshold values use below help command.