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Mac OS X freezes when switching network locations, or network ports
Several readers are reporting repeated system freezes in Mac OS X when switching network locations. Locations are sets of network preferences that can be toggled on the fly, frequently used by portable Mac users when accessing different services in different physical locations, or by users who routinely switch between wired and wireless networks (if one network requires a manually entered IP address, for instance).
There are also reports of freezes that occur when simply switching network ports -- that is, from AirPort to Ethernet or vice versa, for instance.
Some typical reports from an Apple Discussions thread:
"Exactly the same problem here, switching from a wireless to a wired location. (No problem the other way around.) I tried enabling Ethernet within the wireless location, and the moment I applied the change, my MacBook Pro froze. "
"I use DHCP when using wireless and a manual IP address when connected to my home Gbit ethernet. Whenever I switch, I seem to have a 50/50 chance of a total freeze."
Fixes
So far, the most reliable fix we've seen for the network location switching-freeze issue is to simply eliminate all network locations and rely on DHCP connectivity -- obviously a less-than-ideal solution.
If the freezes occur when plugging in an Ethernet cable, switching to AirPort connectivity, or otherwise simply switching the network port being used try the following:
- Turn off AirPort before plugging in the Ethernet cable
- Avoid connecting or disconnecting network cables after Mac has gone to sleep -- do it prior to a sleep session.
- Perform a deep clean of system caches with a tool like Cocktail or Tiger Cache Cleaner.
- Make sure that the port you will be using at the top of the list of available ports in the Network pane of System Preferences.
Feedback? Late-breakers@macfixit.com.
Resources
Network problems, especially using Personal File Sharing, are the most frequent cause of freezes in my experience. There are any number of things you can do to freeze OS X with network issues. This has been discussed before and it seems to me that the problems occur at more than one level. There's the network stack itself, which should be more robust and then there's the Finder which should be more multithreaded and better able to handle failures of any kind of disk connection much better than it currently does.
Take a PowerBook or MacBook mount an AppleShare volume, use it with a few applications, put it in sleep mode, unplug it and take it somewhere, forgetting to unmount the AppleShare volume first. Most of the time, you will have to reboot to get the machine working again.
And don't forget the most common reason for freezes (actually, just very, very long time outs) on location switches. Unmount all of your network drives before switching locations! (And please, someone make a Location manager that lets you define things to do *before* switching the network?)
I've had a "disconnected" location on my Powerbooks for years. In the past it's been very helpful (and extends batttery life when I'm not on a network) but lately on my new MacBook Pro, I've seen a LOT of this freezing (or whatever you'd call it) when switching to my default Automatic location. This didn't ever happen on my previous Powebooks. It doesn't seem to matter what I'm swtiching from -- DHCP or Manual TCP/IP. I thought it had something to do with the particular settings in "Automatic". From these posts, it might just be a function of where it is in the Location stack. I'm very surprised Apple hasn't fixed the problem or at least set up a warning system of some kind, if it's been going on for so long.
In the case of Apple Personal File Sharing this may repeatedly be demonstrated by mounting a remote disk on a local machine and then switching the local machine's network location.
This is one of those "rock, meet hard place" situations. A filestore is a cached object. In other words, information is kept in the memory of the local machine that needs to be updated on the remote machine in order to guarantee remote filestore continuity. MacOS X has a long timeout (several minutes) where they wait patiently for the remote machine to reappear before they put up a dialog box and trash the corresponding cached information. I do not know how MacOS X avoids remote filestore corruption on one of these timeouts.
It is a shame that MacOS X does not handle this better. It is almost certainly a holdover from Finder single-threaded days. The best way to avoid this known, but so far largely ignored (by Apple) problem, is to be sure to dismount remote volumes in the Finder before switching network settings.
I use an AirPort network with a manually set IP address at home, but regularly connect to DHCP WiFi hot spots and wired Ethernet connections and have never experienced a freeze - not with a G3 iBook, G4 iBook or Mac Book Pro running Jaguar, Panther or Tiger.
Just a data point.
You're right. If you remember to close down network connections, you're fine. The thing is that long-time Mac users, such as myself, expect a higher level of quality out of software than most people do. You shouldn't have such consequences from a simple predictable mistake.
- by baddawg65 October 16, 2007 11:17 AM PDT
- I noticed this "freezing" more ever since the MacBook Pro firmware update. I had my MacBook Pro since November 2006 and I never got this "freeze" but since the update I noticed it more. My MacBook Pro doesn't really "freeze" but the network connection seems not to be recognized by network port on the switch, it would appear to connect then drop for no reason and it appears that the drop occurs from the Mac side because I have a managed switch in which I can monitor the ports on the switch. I tried several thing but I found if I toggle between one of my network location settings and back my work location then the network connection appears to work. The only difference between my home and work location is I have AppleTalk enabled at work.
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