volumes::create_capacity

Tag 6: a client asks how large a volume it could create; the server sends exactly one response carrying the largest size, in bytes, of a volume the client could create at that time, or an error, and the scope finishes; the answer reserves nothing.

A client opens the scope with a request whose payload is the tag byte 6 and nothing more. The server sends exactly one response, which carries either a number of bytes or an error. The response finish follows the response, and no frame follows the finish.

• The request. The request carries no parameter; the tag is the whole of it. Request states its form.
• The capacity. The number is the largest size, in bytes, of a volume that the client could create by a volumes::create request at the time of the response. It is the size of the largest single volume the server could make for the client, and not the sum of the server’s room. The number 0 states that the client can create no volume at the time of the response. Response states its form.
• No reservation. The answer is a fact about the time of the response and reserves nothing. A volumes::create request stating a size not greater than the number answered may be answered with insufficient capacity when the room has been taken between the two responses. A volumes::create request stating a size greater than the number answered, made while the capacity is unchanged, is not answered with the byte 0.
• The client. The client is the identity under which the connection was authorized, as Authorization provides. The number is the capacity available to that identity.
• The error. An error states that the server did not answer the question, and that nothing was determined about the capacity. An error is not the number 0.