EBS / Client / put_snapshot_block



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-KiB sectors.


You should always retry requests that receive server ( 5xx) error responses, and ThrottlingException and RequestThrottledException client error responses. For more information see Error retries in the Amazon Elastic Compute Cloud User Guide.

See also: AWS API Documentation

Request Syntax

response = client.put_snapshot_block(
  • SnapshotId (string) –


    The ID of the snapshot.


    If the specified snapshot is encrypted, you must have permission to use the KMS key that was used to encrypt the snapshot. For more information, see Using encryption in the Amazon Elastic Compute Cloud User Guide..

  • BlockIndex (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.

  • BlockData (bytes or seekable file-like object) –


    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.

  • DataLength (integer) –


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

    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.

  • ChecksumAlgorithm (string) –


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

Return type:



Response Syntax

    'Checksum': 'string',
    'ChecksumAlgorithm': 'SHA256'

Response Structure

  • (dict) –

    • 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.


  • EBS.Client.exceptions.AccessDeniedException

  • EBS.Client.exceptions.ValidationException

  • EBS.Client.exceptions.ResourceNotFoundException

  • EBS.Client.exceptions.RequestThrottledException

  • EBS.Client.exceptions.ServiceQuotaExceededException

  • EBS.Client.exceptions.InternalServerException