Home > Storage > PowerScale (Isilon) > Industry Solutions and Verticals > Media and Entertainment > PowerScale OneFS: macOS Client Performance and User Experience Optimization > About Apple SMB extensions
Apple has added several macOS-specific features to their implementation of SMB. Primarily, these features address the handling of file metadata stored in alternate data streams as described previously. OneFS supports these features:
ReadDirAttr: This feature changes how macOS handles reads of file metadata stored in an alternate data stream when listing the contents of large directories. Finder info, access rights, and resource fork size are returned more efficiently for the files in the directory.
OsxCopyFile: With the SMB2 protocol, Microsoft implemented server-side optimizations when copying files between directories on the file share. The extension introduced by Apple ensures that all Apple-specific file metadata is properly copied along with the file itself. The copy process is also simplified because it is performed in one request, as opposed to splitting the requests into logical chunks. When performing a large server-side copy, the macOS Finder ignores updates from the server. During these copies, the Finder copy progress bar does not update and may appear to have stopped responding. When the copy finishes, the progress bar snaps to complete.
In versions 10.13+, macOS has changed how it interacts with SMB servers to pull directory file listings. Unintuitively, the Apple SMB extensions can slow performance in workflows that have directories with high file counts or elaborate project files (such as complicated video edit projects). Disabling Apple extensions in OneFS improves performance in those situations.