JWFA

OK... so I have resolved the problem.  This was a network issue:

My network config looked like this:
 
# Generated settings: IFNAME[0]="br0" BONDNAME[0]="bond0" BONDING_MIIMON[0]="100" BRNAME[0]="br0" BRSTP[0]="no" BRFD[0]="0" BONDING_MODE[0]="1" BONDNICS[0]="eth0" BRNICS[0]="bond0" PROTOCOL[0]="ipv4" USE_DHCP[0]="no" IPADDR[0]="10.0.0.10" NETMASK[0]="255.255.254.0" GATEWAY[0]="10.0.0.1" DNS_SERVER1="10.0.0.1" USE_DHCP6[0]="yes" DHCP6_KEEPRESOLV="no" VLANS[0]="1" SYSNICS="1" VLANS[0]="1,103"
The output from my original post contains the clue:
 
bond0: (slave eth0): Enslaving as a backup interface with a down link
I simply edited my config to as simple as possible:
 
# Generated settings: # Default settings: IFNAME[0]="eth0" PROTOCOL[0]="ipv4" USE_DHCP[0]="yes"
And my host came up after booting with this. 

Obviously this is not a generic solution to this problem. Simply put `udev` was failing to bring up the interface. In order to debug this you need to boot the server into single user mode by adding `single` to the kernel's boot paramters.

Or you can edit `syslinux.cfg-` as follows:

 
default menu.c32 menu title Lime Technology, Inc. prompt 0 timeout 50 label Unraid OS menu default kernel /bzimage append initrd=/bzroot label Unraid OS GUI Mode kernel /bzimage append initrd=/bzroot,/bzroot-gui label Unraid OS Safe Mode (no plugins, no GUI) kernel /bzimage append initrd=/bzroot unraidsafemode label Unraid OS GUI Safe Mode (no plugins) kernel /bzimage append initrd=/bzroot,/bzroot-gui unraidsafemode label Memtest86+ kernel /memtest label Single User Mode kernel /bzimage append initrd=/bzroot single
Once in single user mode you can debug the issue. I established that simply brining up the interface manually by doing:

 
/sbin/ip link set eth0 up /sbin/ip addr add 10.0.0.10/24 dev eth0 # edit this for your network obviously /sbin/ip route add default via 10.0.0.1
Given that I know the interface was working I followed the steps to manually bring up the bond0, and it failed so I knew the config was gronked. I reverted to the simple dhcp config and that resolved my problem.

I hope this helps other users.