Table Of Contents


User Guide

First time using the AWS CLI? See the User Guide for help getting started.

Note: You are viewing the documentation for an older major version of the AWS CLI (version 1).

AWS CLI version 2, the latest major version of AWS CLI, is now stable and recommended for general use. To view this page for the AWS CLI version 2, click here. For more information see the AWS CLI version 2 installation instructions and migration guide.

[ aws . ebs ]



Writes a block of data to a snapshot. If the specified block contains data, the existing data is overwritten. The target snapshot must be in the pending state.

Data written to a snapshot must be aligned with 512-byte sectors.

See also: AWS API Documentation

See 'aws help' for descriptions of global parameters.


--snapshot-id <value>
--block-index <value>
--block-data <value>
--data-length <value>
[--progress <value>]
--checksum <value>
--checksum-algorithm <value>
[--cli-input-json <value>]
[--generate-cli-skeleton <value>]


--snapshot-id (string)

The ID of the snapshot.

--block-index (integer)

The block index of the block in which to write the data. A block index is a logical index in units of 512 KiB blocks. To identify the block index, divide the logical offset of the data in the logical volume by the block size (logical offset of data/524288 ). The logical offset of the data must be 512 KiB aligned.

--block-data (blob)

The data to write to the block.

The block data is not signed as part of the Signature Version 4 signing process. As a result, you must generate and provide a Base64-encoded SHA256 checksum for the block data using the x-amz-Checksum header. Also, you must specify the checksum algorithm using the x-amz-Checksum-Algorithm header. The checksum that you provide is part of the Signature Version 4 signing process. It is validated against a checksum generated by Amazon EBS to ensure the validity and authenticity of the data. If the checksums do not correspond, the request fails. For more information, see Using checksums with the EBS direct APIs in the Amazon Elastic Compute Cloud User Guide .

--data-length (integer)

The size of the data to write to the block, in bytes. Currently, the only supported size is 524288 .

Valid values: 524288

--progress (integer)

The progress of the write process, as a percentage.

--checksum (string)

A Base64-encoded SHA256 checksum of the data. Only SHA256 checksums are supported.

--checksum-algorithm (string)

The algorithm used to generate the checksum. Currently, the only supported algorithm is SHA256 .

Possible values:

  • SHA256

--cli-input-json (string) Performs service operation based on the JSON string provided. The JSON string follows the format provided by --generate-cli-skeleton. If other arguments are provided on the command line, the CLI values will override the JSON-provided values. It is not possible to pass arbitrary binary values using a JSON-provided value as the string will be taken literally.

--generate-cli-skeleton (string) Prints a JSON skeleton to standard output without sending an API request. If provided with no value or the value input, prints a sample input JSON that can be used as an argument for --cli-input-json. If provided with the value output, it validates the command inputs and returns a sample output JSON for that command.

See 'aws help' for descriptions of global parameters.


Checksum -> (string)

The SHA256 checksum generated for the block data by Amazon EBS.

ChecksumAlgorithm -> (string)

The algorithm used by Amazon EBS to generate the checksum.