SMB (Samba) Server-Side Copy Support: Enabled for Mac OS?

TrueNAS General
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I’ve updated the feature request with additional information from the Samba dev team regarding why the defaults on Mac OS are set as they are: Enable Mac SMB (Samba) Server-Side Copy Support by Default or Provide a Toggle in SMB Service Advanced Options - #9 by SinisterPisces

You can see the dev’s response and my original message here: https://lists.samba.org/archive/samba/2025-May/251551.html

There are two styles of SSC:

  • the “normal” protocol style called copy-chunk, where the copy is
    requested in IO ranges by the client and performed server-side
  • the Apple way enabled by fruit:copyfile where the client requests the
    whole file to be copied in one request to be performed by the server

The problem with the latter is that for large file the copy takes some
time and meanwhile the client is blocked waiting for IO to complete. If
the copy takes longer then the SMB request timeout time (iirc default
30s) the requests times out and the client will disconnect the connection.

My recommendation is to stay away from fruit:copyfile for these reasons.

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