While creating a storage gateway cached iSCSI volume, you would want setup CHAP authentication on the volumes. To configure CHAP authentication, you would need to provide Initiator Name, Initiator Secret and Target Secret.
You can get the Initiator name from the client Windows ISCSI initiator configuration as shown below. Next, provide any Initiator secret and Target secret values. Make sure they are not identical and longer than 12 and less than 16 characters.
After saving the CHAP configuration, you would need to provide Target Secret under CHAP in the Configuration tab. This is the Target Secret that was provided in above Volume CHAP configuration provided in the AWS Storage Gateway console.
Then, from the Discovery tab in iSCSI client, select Discover Portal, provide the IP address of the storage gateway as target, select Advanced. Under General, Enable CHAP log on, provide Initiator Secret under Target Secret, enable Perform mutual authentication and select OK. This is the Initiator Secret that was provided in above Volume CHAP configuration provided in the AWS Storage Gateway console.
Feel free to comment if you have any questions.