TECH Signal 498
Synology to UniFi UNAS Pro 8 migration requires Robocopy to skip NTFS alternate data streams
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Migrating files to a UniFi UNAS Pro 8 fails with Windows error 665 when files contain NTFS Alternate Data Streams, requiring specific Robocopy flags to bypass the limitation.
Engineers migrating data to UniFi NAS devices may encounter silent failures on files with NTFS Alternate Data Streams. Using Robocopy with the /COPY:DATX flag bypasses this filesystem limitation, but permanently strips those streams from the destination.
Written by elseif from the cluster below · every claim links back to a sourceThe three things worth knowing
Explorer and Robocopy fail with Windows error 665 when writing files with NTFS Alternate Data Streams to the UniFi UNAS Pro 8.
Adding the X flag to Robocopy's /COPY and /DCOPY parameters skips these streams and allows the transfer to complete.
Robocopy's /Z restartable mode severely degrades transfer speeds on fast networks and should be removed.
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