How Amazon DataSync transfers work - Amazon DataSync
DataSync architectureConcepts and terminologyHow DataSync transfers files and objects
Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

How Amazon DataSync transfers work

Learn the key concepts and terminology related to Amazon DataSync transfers.

DataSync architecture

The following diagrams show how and where DataSync commonly transfers storage data. For a full list of DataSync supported storage systems and services, see Where can I transfer my data with Amazon DataSync?.

Transferring between on-premises storage and Amazon

The following diagram shows a high-level overview of DataSync transferring files between self-managed, on-premises storage systems and Amazon Web Services.

An overview of a common DataSync scenario where data transfers from an on-premises storage system to a supported Amazon storage resource (such as an Amazon S3 bucket or Amazon EFS file system).

The diagram illustrates a common DataSync use case:

  • A DataSync agent copying data from an on-premises storage system.

  • Data moving into Amazon via Transport Layer Security (TLS).

  • DataSync copying data to a supported Amazon storage service.

Transferring between Amazon storage services

The following diagram shows a high-level overview of DataSync transferring files between Amazon Web Services in the same Amazon Web Services account.

An overview of a common DataSync scenario where data transfers between Amazon storage resources (such as an Amazon S3 bucket or Amazon EFS file system).

The diagram illustrates a common DataSync use case:

  • DataSync copying data from a supported Amazon storage service.

  • Data moving across Amazon Web Services Regions via TLS.

  • DataSync copying data to a supported Amazon storage service.

When transferring between Amazon storage services (whether in the same Amazon Web Services Region or across Amazon Web Services Regions), your data remains in the Amazon network and doesn't traverse the public internet.

Important

You pay for data transferred between Amazon Web Services Regions. This is billed as data transfer OUT from your source Region to your destination Region. For more information, see Data transfer pricing.

Transferring between cloud storage systems and Amazon storage services

With DataSync, you can transfer data between other cloud storage systems and Amazon Web Services. In this context, cloud storage systems can include:

Concepts and terminology

Familiarize yourself with DataSync transfer features.

Agent

An agent is a virtual machine (VM) appliance that DataSync uses to read from and write to storage during a transfer.

You can deploy an agent in your storage environment on VMware ESXi, Linux Kernel-based Virtual Machine (KVM), or Microsoft Hyper-V hypervisors. For storage in a virtual private cloud (VPC) in Amazon, you can deploy an agent as an Amazon EC2 instance.

A DataSync transfer agent is no different than an agent that you can use for DataSync Discovery, but we don't recommend using the same agent for these scenarios.

To get started, see Create an agent.

Location

A location describes where you're copying data from or to. Each DataSync transfer (also known as a task) has a source and destination location. For more information, see Where can I transfer my data with Amazon DataSync?.

Task

A task describes a DataSync transfer. It identifies a source and destination location along with details about how to copy data between those locations. You also can specify how a task treats metadata, deleted files, and permissions.

Task execution

A task execution is an individual run of a DataSync transfer task. There are several phases involved in a task execution. For more information, see Task execution statuses.

How DataSync transfers files and objects

When you start a transfer, DataSync examines your source and destination storage systems to determine what to sync. It does this by recursively scanning the contents and metadata of both systems to identify differences between the two. This can take just minutes or a few hours depending on the number of files or objects involved (including the performance of the storage systems).

DataSync then begins moving your data (including metadata) from the source to destination based on how you set up the transfer. For example, DataSync always performs data-integrity checks during a transfer. When the transfer's complete, DataSync can also verify the entire dataset between locations or just the data you copied. (In most cases, we recommend verifying only what was transferred.) There are options for filtering what to transfer, too.

How DataSync verifies data integrity

DataSync locally calculates the checksum of every file or object in the source and destination storage systems and compares them. Additionally, DataSync compares the metadata of every file or object in the source and destination.

If there are differences in either one, verification fails with an error code that specifies precisely what failed. For example, you might see error codes such as Checksum failure, Metadata failure, Files were added, Files were removed, and so on.

For more information, see Configuring how Amazon DataSync verifies data integrity.

How DataSync handles open and locked files

Keep in mind the following when trying to transfer files that are in use or locked:

  • In general, DataSync can transfer open files without any limitations.

  • If a file is open and being written to during a transfer, DataSync can detect this kind of inconsistency during the transfer task's verification phase. To get the latest version of the file, you must run the task again.

  • If a file is locked and the server prevents DataSync from opening it, DataSync skips the file during the transfer and logs an error.

  • DataSync can't lock or unlock files.