AWS Storage Gateway User Guide
Volume Gateways
In the cached volumes solution, AWS Storage Gateway stores all your on-premises application data in
a storage volume in Amazon S3. The following diagram provides an overview of the cached volumes
deployment.
After you install the Storage Gateway software appliance—the VM—on a host in your data center and
activate it, you use the AWS Management Console to provision storage volumes backed by Amazon S3.
You can also provision storage volumes programmatically using the AWS Storage Gateway API or the
AWS SDK libraries. You then mount these storage volumes to your on-premises application servers as
iSCSI devices.
You also allocate disks on-premises for the VM. These on-premises disks serve the following purposes:
•
Disks for use by the gateway as cache storage
– As your applications write data to the storage
volumes in AWS, the gateway first stores the data on the on-premises disks used for cache storage.
Then the gateway uploads the data to Amazon S3. The cache storage acts as the on-premises durable
store for data that is waiting to upload to Amazon S3 from the upload buffer.
The cache storage also lets the gateway store your application's recently accessed data on-premises for
low-latency access. If your application requests data, the gateway first checks the cache storage for the
data before checking Amazon S3.
You can use the following guidelines to determine the amount of disk space to allocate for cache
storage. Generally, you should allocate at least 20 percent of your existing file store size as cache
storage. Cache storage should also be larger than the upload buffer. This guideline helps make sure
that cache storage is large enough to persistently hold all data in the upload buffer that has not yet
been uploaded to Amazon S3.
•
Disks for use by the gateway as the upload buffer
– To prepare for upload to Amazon S3, your
gateway also stores incoming data in a staging area, referred to as an
upload buffer.
Your gateway
uploads this buffer data over an encrypted Secure Sockets Layer (SSL) connection to AWS, where it is
stored encrypted in Amazon S3.
You can take incremental backups, called
snapshots
, of your storage volumes in Amazon S3. These
point-in-time snapshots are also stored in Amazon S3 as Amazon EBS snapshots. When you take a new
snapshot, only the data that has changed since your last snapshot is stored. You can initiate snapshots
on a scheduled or one-time basis. When you delete a snapshot, only the data not needed for any other
snapshots is removed. For information about Amazon EBS snapshots, see
You can restore an Amazon EBS snapshot to a gateway storage volume if you need to recover a backup
of your data. Alternatively, for snapshots up to 16 TiB in size, you can use the snapshot as a starting
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