How Do I Troubleshoot Redis Connection Failures?

Preliminary checks:

• Check the connection address.

  Obtain the connection address from the instance basic information page on the DCS console.

• Check the instance password.

  If the instance password is incorrect, the port can still be accessed but the authentication will fail.

• Check the port.

  Port 6379 is the default port used in intra-VPC access to a DCS Redis instance.

• Check if the maximum bandwidth has been reached.

  If the bandwidth reaches the maximum bandwidth for the corresponding instance specifications, Redis connections may time out.

• For a DCS Redis 3.0 instance, check the inbound access rules of the security group.

  Intra-VPC access: If the Redis client and the Redis instance are bound with different security groups, allow inbound access over port 6379 for the security group of the instance.

  For details, see Security Group Configurations.

• For a DCS Redis 4.0/5.0 instance, check the whitelist configuration.

  If the instance has a whitelist, ensure that the client IP address is included in the whitelist. Otherwise, the connection will fail.

  For details, see Managing IP Address Whitelist.

  If the client IP address has changed, add the new IP address to the whitelist.

• Check the configuration parameter notify-keyspace-events.

  Set notify-keyspace-events to Egx.

Further checks:

• Jedis connection pool error
• Error "Read timed out" or "Could not get a resource from the pool"

  Check if the KEYS command has been used. This command consumes a lot of resources and can easily block Redis. Instead, use the SCAN command and avoid executing the command frequently.