Member Avatar for martin quince

My mixed network of Macs and PCs are served by a NT server, the macs run OS 8.6, 9.1, 10.2, 10.3, the OS X macs connect to the server but drop the connection after a period of time, reconnecting is easy it's just a nuisance, any help appreciated.

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Summary tied to the thread: reports OS X 10.2/10.3 clients lose SMB shares after a short idle period while older OS 8/9 clients stay connected; confirmed the drop happens when idle; notes the problem can coincide with heavy server load and has already tried changing NIC/network settings without success.

Likely classes of root cause (what to check)

  • Server-side SMB idle/session policy. Windows can drop idle SMB sessions after a configured timeout; checking the server for session tear-downs is a priority.
  • Client-side keepalive behavior in early OS X SMB code. OS X clients historically probe far less often than some network gear expects.
  • Network gear or NIC power-management/duplex problems that terminate dormant TCP sessions. Heavy server load can make a server slow to respond and trigger timeouts.

Practical diagnostics (non-destructive)

  • Capture traffic from an affected Mac when the disconnect happens to see whether the server sends FIN/RST or the TCP stream simply stalls. A useful capture command:
    sudo tcpdump -i en0 -s 0 -w ~/smb.pcap port 139 or port 445

    Open the .pcap in Wireshark and look for a server-originated FIN/RST or for ICMP/network errors at the time of disconnect. That distinguishes “server closed the SMB session” from “network dropped an idle TCP flow.”

Quick checks and safe workarounds

  • Inspect Windows Event Viewer around the disconnect time for Server/Lanman-related session messages and check server CPU/disk/NIC counters during the window.
  • Apply latest OS X updates/hotfixes and server service packs — many SMB issues were fixed in Apple and Microsoft updates around this era.
  • As a temporary mitigation, run a lightweight background keepalive on an affected Mac that stats a small file on the share every few minutes (test on one machine first).
  • Back up server configuration/registry before any changes and test one client at a time.

These steps will identify whether the server, the network, or the OS X SMB client is responsible and point to a permanent fix (server timeout tuning, NIC/firmware fixes, or client keepalive tuning).

Recommended Answers

All 6 Replies

Member Avatar for kc0arf

Hello Martin,

Do the OS X Macs disconnect after being idle for a few minutes? Are we talking minutes or hours? If the users are working on the computers, do they still drop off?

Thanks,

Christian

Member Avatar for martin quince

Hello Martin,

Do the OS X Macs disconnect after being idle for a few minutes? Are we talking minutes or hours? If the users are working on the computers, do they still drop off?

Thanks,

Christian

It seems to if they are not being used - after a few minutes

Thanks

Martin

Member Avatar for trollinson

I have had the same problems, I am currently running a win2000 network and servers with about 25 OSX boxes utilising the network also. The thing I have noticed is that the OSX machines time out when the servers are being used heavily or there is a couple people using a specific folder stucture. I believe that if there is anyway you can set the time out function under osx to a longer period this(" I believe this is the reason") that it disconnects people. This is a BIG issue for me and spending alot of time on resolving this issue. I shall post my finding over the next week or so.

Member Avatar for martin quince

I have had the same problems, I am currently running a win2000 network and servers with about 25 OSX boxes utilising the network also. The thing I have noticed is that the OSX machines time out when the servers are being used heavily or there is a couple people using a specific folder stucture. I believe that if there is anyway you can set the time out function under osx to a longer period this(" I believe this is the reason") that it disconnects people. This is a BIG issue for me and spending alot of time on resolving this issue. I shall post my finding over the next week or so.

I seem to recall reading something about adjusting packet sizes in the ethernet pane, but I'm not sure it was to do with this problem!!
Martin

Member Avatar for trollinson

I seem to recall reading something about adjusting packet sizes in the ethernet pane, but I'm not sure it was to do with this problem!!
Martin

I have given that ago but have still had the same problem!! This is getting annoying!! I have tried several different things with the packet sizes but with no luck. I am thinking of putting another mirrored set in and increase the bandwidth by adding another 100Mb network card in the server and see if that works. I dont have a high level of unix expierence so i dont want to start playing with the inner workings as yet!! Any Ideas and I definatly up for it!!

Member Avatar for kc0arf

Hi,

I wish I could simulate this in my lab and work with you on a fix.

Christian

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