Environment

Clustered Data ONTAP 8.3

Symptoms

It takes around 1 to 10 minutes to access the SMB/CIFS share from a MAC client.

Cause

Packet trace displays that there is no issue with the controller response times, and the issue is with the client side settings.

The SMB LargeMTU feature allows an SMB client to issue a single request of up to 1MB. Without support for this feature, SMB clients (both Apple and Mac) are limited to 64KB max request size. Windows clients get around the lack of support for this feature by using another Windows feature called pipelining. Pipelining allows an SMB client to issue multiple outstanding requests without waiting for a response.
Apple supports this feature as well; however, they limit their client to just a few outstanding pipelined requests (less than 4 total outstanding requests versus Windows which regularly goes well above that). So despite a lack of support for LargeMTU, Windows clients have a better performance experience on SMB2.x than Apple because they better utilize pipelining, in place of the absence of LargeMTU with clustered Data ONTAP.

Apple Spotlight file indexer is a common cause for slowness in accessing CIFS shares.

Solution

Perform the following steps to resolve the issue:

• Add nsmb.conf to ~/Library/Preferences/ with the following details:
[default]
smb_neg=smb1_only

• Set Other-Networks and Static IP address in Network Preference.

• Connect to smb://pathname

Additional settings for improving Mac SMB peformance:

• Exclude network shares from Spotlight searching:
Open System Preferences, Spotlight, and add all the network shares to the exclusion list.

• Disable updating .DS_Store files within network share folders:
Run from a terminal window:
Defaults write com.apple.desktopServices DSDDontWriteNetworkStores true
Two additional settings, Disable ARP requests validation and Revert TCP ACK to compatabilility mode, are also available.
http://www.sysadminfaq.com/2014/06/mac-os-x-mavericks-finder-slow.html

On Oct 29, 2015, at 7:50 PM, Christopher S Eno <s.eno@me.com> wrote:

"CIFS or SMB" meaning they've tried both "cifs://servername" (SMB1) and "smb://servername" (SMB2+) to mount shares from Macs with lousy results for both?

Is your CIFS share configured to provide any of the SMB3 features like statefull connections, etc.?

On Oct 29, 2015, at 7:38 PM, Rue, Randy <rrue@fredhutch.org> wrote:

You're been hearing from me a lot lately.

We're having trouble with a small but distinct number of Mac users connecting via either CIFS or SMB and getting slow connections, an rsync of a test file shows a transfer speed of 500KB/s. Most of the problem children are older versions but at least one is running El Capitan, the latest greatest. On the clients that have the problem, they have it reliably. Sounds like a workstation issue but we're still hoping to give the users a solution.

Anybody know of any known issues with Macs and CDOT 8.3? Solutions?

Randy

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