backup format Combinations of these functions are usual. Default sorting schematics spanning the retrieval interface generally rely on zero-fault content processing, which carries the obvious requirement that two or more of the above functions are synchronized. Extensions Nearly all object storage gateways support Amazon S3 protocol as a quasi-standard. Some offer as well Microsoft Azure Blob, Google Storage, or Openstack SWIFT. Most gateways support public cloud storage e.g. from Amazon or Microsoft as an object store and Dropbox as a file drive store, there are as well a lot of vendors that support private cloud storage as well – including off and on prem storage. Deployment methods There are multiple variants to deploy such gateways – and some vendors support as well different variants as of their product line: bare metal hardware appliance software appliance supporting different hypervisors software on top of an operating system – aka FUSE based Software appliances as well as FUSE-based gateways can be installed on public cloud infrastructures. Advantages Cloud storage gateways avoid the need to change existing applications by providing a standard interface. Additionally, IT users are used to existing protocols – like SMB or NFS. They can make use of cloud storage with the advantage of still using their existing infrastructures (including e.g. Active Directory, LDAP integration, fileshare functions etc.). While cloud storage gateways initially covered a niche only, they got more attraction as of multi-cloud technologies. As an example: It is possible to run a cloud storage gateway in form of a software appliance on top of a public or private cloud infrastructure by offering docker volume drivers that enable containers for automatic provisioning of storage used by these containers in a consistent form. They are using the hypervisors disks as a cache only, but destage data on least recently used algorithm to the underlying cloud storage. The de facto standard for object storage is Amazon S3 – it had the most popularity and capacity installed on object storage. But every object storage vendor can (and most of them do) offer Amazon S3 storage – even there is no real "standard" S3 API: Every vendor is a little bit different in implementing S3 API (as seen from the different cloud storage gateway vendors supporting the "specific" APIs of the different object storage vendors). Since 2018, an increasing number of cloud storage gateways hide this complexity by offering S3 on northbound (as of