We have a virtualized (ESXi 4.1) Windows Server 2003 server running Exchange 2003 R2 that intermittently drops the network connection for a few minutes every Wednesday and Saturday between 3am EST and 7am EST. The network drops out between 5-15 minutes and happens 2 to 5 times during the 3am to 7am period.
We monitor this server remotely and our monitoring software detects that the server is down. In addition, we use an external spam filtering service and they report the email server is not accepting connections when the network drops.
The server also runs an older version of BES 4 with one or two BBS devices. Sometimes in the event log, the SRP connection to Blackberry will fail, indicating that the server is also having network connection problems during the specified times above. However, this event log warning only appears about 10% of the time, since the network doesn’t stay long.
Since this server is virtualized, I also checked our history for other servers running the VMWare Host, no other guest VMs are dropping during that time. The vSwitch that the Exchange server is running on is the same as the other other guest VMs on that host.
Checked Application and System Logs, nothing indicative of causing network connection loss. System Logs will have 0 entries before and after network drops. Application log will have logs, but nothing that indicates a network connection drop
Checked Network Adapter uptime, does not change.
Changed network adapter from VMWare Flexible to VMWare VMXNET3, no change
Increased Exchange logging, still not event logs that indicate
Checked task scheduler, no tasks on the server and no hidden tasks on the server
Exchange maintenance is set to run DAILY from 1am to 5am, I doubt this is the cause if the server only drops on WED and SAT.
Our backup agent runs at 11pm nightly and never lasts more than 2 hours, so it starts/stops prior to network dropping
I’m really frustrated by Windows Server 2003 lack of logging. If it was a Server 2008+, logging appears to be way better with system components.
Any suggestions as to how to troubleshoot the network dropping b/w 3am and 7am EST on WED and SAT?