# Storage Gateway

**Introduction**

* Connects on-premises data to connect to AWS S3 for backup or caching purpose

**Feature**

* Storage Gateway's software appliance is available for download as a virtual machine image for client's data center
* Types:
  * File Gateway (NFS -> File Gateway -> S3)
    * File Gateway appliance is a virtual machine to bridge between your NFS and S3
    * Metadata and directory structures are preserved
    * Configured S3 buckets are accessible using the NFS and SMB protocol
    * Each File Gateway should have an IAM role to access S3
    * Most recently used data is cached in the File Gateway
    * Scenario
      * work with S3 lifecycle policy
      * work with S3 object versioning
        * Must use the "RefreshCache" API on File Gateway to be notified of restore
      * work with S3 object lock
        * Enables to have the File Gateway for Write Once Read Many (WORM) data
        * If there are file modifications or renames in the file share clients, the File Gateway creates a new version of the object without affecting prior versions, and the original locked version will remain unchanged
  * Volume Gateway (Block storage using iSCSI protocol backed by S3)
    * Data written to volumes can be asynchronously backed up as point-in-time snashots, stored in the cloud as EBS snashots. Snapshots are incremental and also comporessed. (accessing data from S3 through EBS, not to S3 directly)
    * Sub types:
      * Stored Volume 
        * Full data is stored on site, low-latency access, scheduled backups to S3
        * 1Gb \~ 512TB with 32 volumes
      * Cache Volume 
        * Full data is on S3, most frequent accessed data is cached on site
        * 1Gb \~ 1024TB with 32 volumes
    * Can configure [CHAP Authentication](https://docs.aws.amazon.com/storagegateway/latest/userguide/GettingStartedConfigureChap.html) to against playback attacks
  * Tape Gateway (or called Gateway Virtual Tape Library (VTL) for archiving)
    * Ingest data into Glacier
      * If needs further processing after ingestion, use other types of Storage Gateway.
    * Can't asscess single file within tapes, must restore the tape entirely.

**Architectures**

![Extensions with File Gateway](/files/-MEuN_At673UBO28K3mh)


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