Надо через PXE загрузить систему по NFS. Есть такок initrd
#!/bin/nash
mount -t proc /proc /proc
setquiet
echo Mounting proc filesystem
echo Mounting sysfs filesystem
mount -t sysfs /sys /sys
echo Creating /dev
mount -o mode=0755 -t tmpfs /dev /dev
mkdir /dev/pts
mount -t devpts -o gid=5,mode=620 /dev/pts /dev/pts
mkdir /dev/shm
mkdir /dev/mapper
echo Creating initial device nodes
mknod /dev/null c 1 3
mknod /dev/zero c 1 5
mknod /dev/urandom c 1 9
mknod /dev/systty c 4 0
mknod /dev/tty c 5 0
mknod /dev/console c 5 1
mknod /dev/ptmx c 5 2
mknod /dev/rtc c 10 135
mknod /dev/tty0 c 4 0
mknod /dev/tty1 c 4 1
mknod /dev/tty2 c 4 2
mknod /dev/tty3 c 4 3
mknod /dev/tty4 c 4 4
mknod /dev/tty5 c 4 5
mknod /dev/tty6 c 4 6
mknod /dev/tty7 c 4 7
mknod /dev/tty8 c 4 8
mknod /dev/tty9 c 4 9
mknod /dev/tty10 c 4 10
mknod /dev/tty11 c 4 11
mknod /dev/tty12 c 4 12
mknod /dev/ttyS0 c 4 64
mknod /dev/ttyS1 c 4 65
mknod /dev/ttyS2 c 4 66
mknod /dev/ttyS3 c 4 67
echo Setting up hotplug.
hotplug
echo Creating block device nodes.
mkblkdevs
echo "Loading ehci-hcd.ko module"
insmod /lib/ehci-hcd.ko
echo "Loading ohci-hcd.ko module"
insmod /lib/ohci-hcd.ko
echo "Loading uhci-hcd.ko module"
insmod /lib/uhci-hcd.ko
mount -t usbfs /proc/bus/usb /proc/bus/usb
echo "Loading jbd.ko module"
insmod /lib/jbd.ko
echo "Loading ext3.ko module"
insmod /lib/ext3.ko
echo "Loading virtio.ko module"
insmod /lib/virtio.ko
echo "Loading virtio_ring.ko module"
insmod /lib/virtio_ring.ko
echo "Loading virtio_pci.ko module"
insmod /lib/virtio_pci.ko
echo "Loading virtio_blk.ko module"
insmod /lib/virtio_blk.ko
echo "Loading scsi_mod.ko module"
insmod /lib/scsi_mod.ko
echo "Loading sd_mod.ko module"
insmod /lib/sd_mod.ko
echo "Loading libata.ko module"
insmod /lib/libata.ko
echo "Loading ata_piix.ko module"
insmod /lib/ata_piix.ko
echo "Loading ahci.ko module"
insmod /lib/ahci.ko
echo "Loading dm-mod.ko module"
insmod /lib/dm-mod.ko
echo "Loading dm-log.ko module"
insmod /lib/dm-log.ko
echo "Loading dm-mirror.ko module"
insmod /lib/dm-mirror.ko
echo "Loading dm-zero.ko module"
insmod /lib/dm-zero.ko
echo "Loading dm-snapshot.ko module"
insmod /lib/dm-snapshot.ko
echo "Loading dm-mem-cache.ko module"
insmod /lib/dm-mem-cache.ko
echo "Loading dm-region_hash.ko module"
insmod /lib/dm-region_hash.ko
echo "Loading dm-message.ko module"
insmod /lib/dm-message.ko
echo "Loading dm-raid45.ko module"
insmod /lib/dm-raid45.ko
echo "Loading tg3.ko module"
insmod /lib/tg3.ko
echo "Loading bnx2.ko module"
insmod /lib/bnx2.ko
echo "Loading e1000.ko module"
insmod /lib/e1000.ko
echo "Loading e1000e.ko module"
insmod /lib/e1000e.ko
echo Waiting for driver initialization.
stabilized --hash --interval 1000 /proc/scsi/scsi
mkblkdevs
echo Scanning and configuring dmraid supported devices
echo Scanning logical volumes
lvm vgscan --ignorelockingfailure
echo Activating logical volumes
lvm vgchange -ay --ignorelockingfailure VolGroup00
resume /dev/VolGroup00/LogVol01
echo Creating root device.
mkrootdev -t ext3 -o defaults,ro /dev/VolGroup00/LogVol00
echo Mounting root filesystem.
mount /sysroot
echo Setting up other filesystems.
setuproot
echo Switching to new root and running init.
switchroot
APPEND initrd=initrd-2.6.18-419.el5.img ramdisk_size=100000 ksdevice=eth0 ip=dhcp noipv6 url --url nfs://centos