<p>A unique identifier for the snapshot that you are requesting. This identifier must be unique for all snapshots within the Amazon Web Services account.</p> <p>Constraints:</p> <ul> <li> <p>Cannot be null, empty, or blank</p> </li> <li> <p>Must contain from 1 to 255 alphanumeric characters or hyphens</p> </li> <li> <p>First character must be a letter</p> </li> <li> <p>Cannot end with a hyphen or contain two consecutive hyphens</p> </li> </ul> <p>Example: <code>my-snapshot-id</code> </p>

<p>The number of days that a manual snapshot is retained. If the value is -1, the manual snapshot is retained indefinitely. </p> <p>The value must be either -1 or an integer between 1 and 3,653.</p> <p>The default value is -1.</p>