Aspera Transfers skipping random files on CIFS/SMB mount using OS X


Transferring files taken from a CIFS/SMB mount on Mac OS X can lead to the skipping of some files in certain cases of concurrent access to the same folder/files by multiple threads. This has been identified as a bug and a bug report has been sent to Apple.

This bug can occur when transferring more than 90 files and the pre-calculation of session size is turned on in Aspera Server.

Aspera provides two solutions for mitigating this issue.


Disable pre-calculation

Disabling pre-calcluation will prevent the concurrent access inside the CIFS filesystem but will lead to a less desirable side effect for uploads since there will no longer be an ETA reported for the entire session if comprised of multiple files.

Disabling pre-calculation has to be done server side via the UI or via Aspera Console, or command line as below:

/opt/aspera/bin/asconfigurator -x "set_node_data;pre_calculate_job_size,no"

C:\Program Files (x86)\Aspera\<product>\bin\asconfigurator.exe -x "set_node_data;pre_calculate_job_size,no"

Mac OS X
asconfigurator -x "set_node_data;pre_calculate_job_size,no"

where <product> can be Enterprise Server or Point to Point. As well the setting can be applied per group or per user.

ascp custom build

Aspera Provides a custom build that hard disables precalculation of the session size.

The ascp custom build you should use depends on the version of the Aspera Connect browser plug-in you use for transfers.

  • For Connect 3.7.0 and above, use the ascp binary at this link: Install
  • For Connect versions prior to 3.7.0, use the ascp binary attached at the bottom of this article

Then precalc will still be enabled on the server side in order to keep it going for your other clients.

Replace the current ascp binary on the OS X installation with the custom ascp provided. Example (Aspera Connect):

1. Rename ascp to ascp.default

mv /Users/<username>/Applications/Aspera /Users/<username>/Applications/Aspera

2. Copy the new ascp there:

cp path/to/new/ascp /Users/<username>/Applications/Aspera

3. Give the necessary permissions to the new ascp file

chmod 775 /Users/<username>/Applications/Aspera

4. (optional) You can remove all extended attrs to the new ascp:

 xattr-2.7 -c /Users/<username>/Applications/Aspera 

<username> is the user logged in Mac OS X.

For Assistance please contact Aspera Support.



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