blobxfer Current Limitations

Please read this section carefully for any current known limitations to blobxfer.

Client-side Encryption

  • Client-side encryption is currently only available for block blobs and Azure Files.
  • Azure KeyVault key references are currently not supported.


  • File attribute store/restore is currently not supported on Windows.

Resume Support

  • Encrypted uploads/downloads cannot currently be resumed as the Python SHA256 object cannot be pickled.
  • Append blobs currently cannot be resumed for upload.

stdin Limitations

  • stdin uploads without the --stdin-as-page-blob-size parameter will allocate a maximum-sized page blob and then will be resized once the stdin source completes. If the upload fails, the file will remain maximum sized and will be charged as such; no cleanup is performed if the upload fails.
  • stdin sources cannot be resumed.
  • stdin sources cannot be encrypted.
  • stdin sources cannot be stripe vectorized for upload.
  • For optimal performance, --chunk-size-bytes should match the "chunk size" that is being written to stdin. For example, if you were using dd you should set the block size (bs) parameter to be the same as the --chunk-size-bytes parameter.

General Azure File Limitations

Other Limitations

  • MD5 is not computed for append blobs.
  • Empty directories are not created locally when downloading from an Azure File share which has empty directories.
  • Empty directories are not deleted if --delete is specified and no files remain in the directory on the Azure File share.
  • Directories with no characters, e.g. mycontainer//mydir are not supported.
  • /dev/null or nul destinations are not supported.
  • Application of access tiers can only be applied to block blobs on either Blob Storage or General Purpose V2 Storage accounts. Please see this article for more information.