MacOS systems sometimes have issues when accessing SMB (“CIFS”) shares. This article is intended to list issues and potential work-arounds.

These issues may vary with different OS versions or applications, so these suggested work-arounds are only a starting point.

Slow Performance When Accessing CIFS Volumes via Finder

Tips for managing slow performance when accessing CIFS Volumes via Finder, especially deep within a folder structure.

• If Finder is slow verify performance via the command line at the same time as follows:
  1. Start a macOS Terminal window.
  2. Enter cd \Volumes  followed by ls –lag.
  3. cd down the same file structure which you are trying to access via the Finder.
• Typically, the speed is fine via the command line, indicating that macOS and CIFS are performing properly, despite Finder being unacceptably slow. Check whether you can see all of the expected files in the command line.
• Cause: .DS_store files. Macs create and store a hidden file in each sub-directory they access, and each user who accesses the directory via a mac updates these files. The deeper down the folder structure you browse, the worse the performance becomes.
• Possible solutions:
  • Use Command Line vs. the Finder.
  • Speed up browsing on network shares on each mac by altering the use of .DS store files. Additional steps include altering Finder’s behavior, as well as altering caching.

Network Connectivity (speed)

As with any share connection, Mac users with slower network connections will experience file access as below expectations.

• Possible solutions: Upgrade to faster connectivity, if possible.
• Summary: A slow network connection may be exacerbated by the Finder issue above. By increasing the speed of the network connection the impact is reduced, however further action may still be necessary.

Optimizing macOS Share Connections for Your Application

• You may have an I/O intensive application that produces access issues.
• Possible Solution: Simplify the folder structure. Here's an example of a complex structure:

1. Level-1: top of the SMB share.
2. Level-2: Redirected-Folders, parent directory for ...
3. Level-3: NetID based sub-directories for user's data storage.

•  Possible Solution: By setting ACL’s and inheritance properly access or performance issues may be resolved:

1. Do all users (in a particular Active Directory group) need access? If so, grant the group an allow on the folder, set inheritance on, and propagate.
2. Will users need to create new folders or other content? If so, grant the NetID or AD group full permissions and propagate.
3. Always set inheritance on.
4. As a TSP and share administrator, never remove your own access.
5. If ABE is desired there is potentially a conflict with the permissions and propagation.

MacOS Finder, CIFS Versus SMB

MacOS users who map to Windows shares via cifs://files.cornell.edu/OU/SHARE will experience failures. This happens because the cifs prefix forces a SMB1 connection from MacOS, which is no longer supported.

• Bad:     cifs://files.cornell.edu/OU/SHARE
• Good:   smb://files.cornell.edu/OU/SHARE