Network drives were dropping out

grouppolicy_thumb.jpgNetwork drives were dropping out.  We were also seeing 15+ minutes slow logon times at some remote sites.

We’d mostly see the slow logon times with Windows 7.  We’d see the “network drives dropping out” issue with Windows 8.

Looking at OfflineFiles event log we saw several 1004 events logged.  Looking at the details of the event, we’d see details like:
Path \\Noddyland\CorpData$ transitioned to slow link with latency = 140 and bandwidth = 202123

Why was it happening?  The following table might help:

Operating system Slow bandwidth limit Slow latency threshold
Windows XP 64Kbps n/a
Windows Vista <nil> (opt-in policy) n/a
Windows 7 64Kbps 80ms
Windows 8 64Kbps 35ms

From the event above “transitioned to slow link with latency = 140 and bandwidth = 202123“, you can see we had plenty of bandwidth, but our network latency was too high at 140ms.  Which triggered the network share (\\Noddyland\CorpData$) to go Offline.

We fixed the issue by setting Latency=200 for \\Noddyland\CorpData$, in Group Policy Computer Configuration\Administrative Templates\Network\Offline Files\Configure slow-link mode.

References:
“Configure slow-link mode” policy on Vista for Offline Files
Configuring New Offline Files Features for Windows 7 Computers Step-by-Step Guide
Slow-Link with Windows 7 and DFS Namespaces
The “Configure slow-link mode” Policy is not taking effect