Glacier is a companion service to S3, but it is the cold storage option. Cold storage is a service where you are unable to directly access your data; you must lodge a request for data to be restored (to S3), and you will be notified when it is ready. A physical example of cold storage might be backup tapes that are stored in a secure location. Similar to S3, files are referred to as objects. Files are grouped together and stored in archives. Archives can be created and deleted but never modified. Archives are grouped together into vaults, which allow you to control access.

The shortest restoration time is 1 to 5 minutes (with limitations). Standard restoration times take 3 to 5 hours, with some other options available.

The following are some recommended use cases for Glacier:

• Long-term (that is, cold) backups
• Compliance backups