Therefore we setup a separate Dell 2850 with Windows 2003 Server 64-bit, running the free VMware Server. At the time we setup our virtual root management server with a serial GSM modem so that it could send SMS notifications (more on that here). Since our GSM modem was serial based, all we needed to do was plug the cable into the 2850's COM1 port, then add a virtual serial port onto the virtual machine and connect it to COM1.
When VMware released their ESXi hypervisor for free, we decided to change from VMware Server to VMware ESXi. The hypervisor promised better performance and memory management and seemed like a nice upgrade. Unfortunately we soon discovered that VMware ESXi 3.5 update 2 does not support mapping a physical serial port to a virtual serial port.
To work around this problem, we purchased a Digi One SP serial over ethernet device for around $150. So now instead of connecting the modem directly to the COM1 port on the back of the Dell server, it now connects to this device which is connected to an ethernet port. The steps are pretty simple:
- Attach the device directly to a spare ethernet NIC on the back of our Dell server using a cross-over cable. Note that we could just connect it to our existing network infrastructure, but again we wanted the monitoring system to be self contained and able to send pages even if the network was offline.
- In the VMware Infrastructure Client, add a new virtual switch to the ESXi server.
- Shut down the RMS virtual machine to add a new virtual NIC which is assigned to the new switch we just created.
- Power ON the VM and configure the new NIC with an unused private address (in our case 192.168.0.1).
- Uninstall the existing GSM modem from the RMS virtual machine.
- Install the Digi One SP software on the RMS virtual machine. The software takes you through a wizard which detects the device and allows you to configure its IP address (in our case 192.168.0.2). Accept all the defaults to install a "RealPort" virtual COM3 port.
- Install the GSM modem through the control panel and connect it to the new COM3 port.
- Test using the Microsoft SMS Sender and then with Operations Manager.