System fails to boot with "dracut Warning: Boot has failed"

Issue

• Server fails to boot with an error from dracut then kernel panic

dracut Warning: No root device "block:/dev/mapper/vg_hostname-lv_root" found
dracut Warning: LVM vg_hostname/lv_swap not found
dracut Warning: Boot has failed. To debug this issue add "rdshell" to the kernel command line.

• After error, the machine kernel panics

Kernel panic - not syncing: Attempted to kill init!
Pid: 1, comm: init Not tainted 2.6.32-xxx.el6.x86_64 #1
Call Trace:
 [<ffffffff8150cfc8>] ? panic+0xa7/0x16f
 [<ffffffff81073ae2>] ? do_exit+0x862/0x870
 [<ffffffff81182885>] ? fput+0x25/0x30
 [<ffffffff81073b48>] ? do_group_exit+0x58/0xd0
 [<ffffffff81073db7>] ? sys_exit_group+0x17/0x20
 [<ffffffff8100b072>] ? system_call_fastpath+0x16/0x1b