Avamar: Network interface configuration is lost after rebooting an Avamar Virtual Edition (AVE) deployed on Microsoft Hyper-V

On an AVE there is, by default, one network interface created name eth0.

After an AVE reboot, the eth0 interface is not present:

ifconfig eth0

eth0: error fetching interface information: Device not found

The list of available network interfaces confirms that eth0 is missing but a new, unconfigured interface called eth1 is present:

ifconfig -a 

eth1      Link encap:Ethernet  HWaddr 00:15:5D:C8:BC:B4
          BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1080
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:5258453 errors:0 dropped:0 overruns:0 frame:0
          TX packets:5258453 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:3043137745 (2902.1 Mb)  TX bytes:3043137745 (2902.1 Mb)

The eth0 configuration file is present and has been unaltered:

ls -l /etc/sysconfig/network/ifcfg-eth0 

-rw-r--r-- 1 root root 62 Jul 21  2003 /etc/sysconfig/network/ifcfg-eth0

cat /etc/sysconfig/network/ifcfg-eth0

STARTMODE='auto'
BOOTPROTO='static'
IPADDR='10.10.10.10/24'
NETMASK='255.255.255.0'
BROADCAST=''
ETHTOOL_OPTIONS=''
MTU=''
NAME=''
NETWORK=''
REMOTE_IPADDR=''
USERCONTROL='no'

There is no eth1 configuration file:

ls -l /etc/sysconfig/network/ifcfg-eth1

ls: cannot access /etc/sysconfig/network/ifcfg-eth1: No such file or directory

Device messages show that eth0 has been renamed to eth1:

dmesg | grep -i eth0

[ 1678.268338] udev: renamed network interface eth0 to eth1

The /etc/udev/rules.d/70-persistent-net.rules file has an entry for eth0 and an entry for eth1, both with different MAC addresses:

cat /etc/udev/rules.d/70-persistent-net.rules

# PCI device 0x8086:0x100f (e1000)
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:50:56:80:94:f7", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0"
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="00:15:5D:C8:BC:B4", ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="eth*", NAME="eth1"

By default, Microsoft Hyper-V uses dynamic MAC address generation, which causes a different MAC address to be reassigned to the AVE virtual machine:

1. Shut down the AVE.

2. Go to the Settings for the AVE in the Hyper-V manager.

3. Expand the settings for the "Network Adapter" in the left pane, and select "Advanced Features":

4. Select "Static" within the "MAC Address" box (as shown above). The address fields should already be populated with the default assigned by Hyper-V.

5. Press OK to save the settings.

6. Power on the AVE.

7. If there is a Data Domain attached to Avamar, use the command dpnctl start all to restart the Avamar services.