The ESX host in question has multiple physical NIC's. From those physical NIC's, two networks were created and backup physical NIC's were left installed but not configured. The two networks created were production traffic and iSCSI. It was decided that we wanted to take our VM's to tape for backup so two of the leftover physical NIC's were used to create a third backup network. We picked a server to test, shut it down, and added the third NIC to it. After bringing the server back up the backup interface was configured and backups were taken from the server for about a week. At the end of that week, that server, along with the others was given its weekly reboot.
This server never came back online. Through troubleshooting it was discovered that the NIC configurations had somehow gotten scrambled. Where NIC1 was production, NIC2 iSCSI, and NIC3 is backup -- rebooting the server changed it to NIC1 iSCSI, NIC2 production, NIC3 offline. Even removing the third NIC could not save the server and it ultimately had to be rebuilt. I'm trying to figure out why this happened and what I can do to avoid it in the future. I only hope I've provided enough information. Thanks in advance for any help.
