title: Issue with changing storage type in aerospike
body: <p>i’ve just added the new namespace in aerospike, but i’ve make a mistake, i choose storage engine memory but this is wrong, because the storage engine must be device ( in my case). is it safe to change the storage memory of existing namespace? or which way i can go to change that, without deleting namespace? P.S I have a pretty old version 3.7.4 Thank you!</p>