Mavericks' SMB2 problem and fixes

No, it's not just you. Apple's Mavericks is having trouble connecting to some network-attached storage and file servers. Fortunately, there are ways to fix it.
Written by Steven Vaughan-Nichols, Senior Contributing Editor

I am beginning to wonder just how much quality assurance work Apple put into its latest Mac operating system: Mac OS X 10.9, Mavericks.

Sure, Mavericks can make Macs faster, but did anyone test it to see how it worked with Gmail or network-attached storage (NAS) and file servers using the Server Message Block 2 (SMB2) file transfer protocol? It doesn't look like it.

Apple Mavericks Logo
Is Mavericks really ready for prime time? If you need to use network drives, it doesn't look like it.

SMB2 is a later version of the old SMB protocol. Both were introduced by Microsoft for local area network (LAN) file sharing. Since SMB showed up in the late 1980s,  the SMB family has become the most common LAN file sharing protocol. It's used by most network-attached storage (NAS) devices and file servers. SMB2, which was introduced in Windows Vista in 2007, is now supported by Samba and Linux and, so Apple says, by Mac OS X.

Apple's OS X Mavericks hands-on, in pictures

Alas, SMB2 is supported by Mavericks more in theory than in practice. There have been numerous user reports of not being able to connect at all with their NAS and file servers. Others are reporting that they can't get iWorks to write to network drives using SMB2.

What's especially annoying: It's not as though Apple decided to add SMB2 at the last minute. Apple quietly announced that it was replacing its ancient Apple Filing Protocol (AFP) with SMB2 in July. In addition, Apple has been using its own SMBX file server for SMB2 support, instead of Samba, since the Lion release. There's nothing new here... including that SMBX has often been criticized for its slow file transfer performance in earlier versions.

Fortunately, there are ways to mitigate this problem. First, and both crudest and simplest, is to force your Mavericks Mac to use SMB instead of SMB2.

To do this you'll need to create a nsmb.conf file in your home directory with the path ~/Library/Preferences/nsmb.conf. There are several ways to do this. First, you can up a terminal from Utilities and paste in the following line from the shell prompt:

echo "[default]" >> ~/Library/Preferences/nsmb.conf; echo "smb_neg=smb1_only" >> ~/Library/Preferences/nsmb.conf

The above must be entered as a single line with a return at the end. You can also create this configuration file with a text editor such as vi from the terminal. Do not, however, try to create this file with a word processor. You'll end up with formatting characters in the file that will ruin it for configuration purposes.

You can also try forcing Mavericks to use the older SMB variant, Common Internet File System (CIFS). To do this, simply edit your server connection URL so that it uses CIFS. Use the Finder to choose the "Go" menu and select "Connect to Server..." (or just use command-K) and type "cifs://YourServerName" and hit Return; the server should mount. If it doesn't, try entering the share's designation as well, e.g. "cifs://YourServerName/YourDriveName."

However, none of these may work depending on whether your file server or NAS supports SMB or CIFS. While they're almost certain to support them, their default settings may not support these older protocols. In that case, you — or your network administrator — will need to set them to support SMB and/or CIFS.

The best thing you could do — which is probably too late if you're already reading this — is to hold off "upgrading" to Mavericks. It seems to me to be one good update away from being ready for prime time.

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