[Transformer TF300T Q&A, Help & Troubleshooting] cmendonc2:
I tried backing up in CWM, but it gives an error about backing up the boot image.

Starting recovery on Thu Feb 28 01:07:56 2013
can't open /dev/tty0: No such file or directory
framebuffer: fd 3 (1280 x 800)
CWM-based Recovery v6.0.2.3
recovery filesystem table
=========================
0 /tmp ramdisk (null) (null) 0
1 /system ext4 /dev/block/mmcblk0p1 (null) 0
2 /cache ext4 /dev/block/mmcblk0p2 (null) 0
3 /misc emmc /dev/block/mmcblk0p3 (null) 0
4 /boot emmc boot (null) 0
5 /recovery emmc recovery (null) 0
6 /staging emmc /dev/block/mmcblk0p4 (null) 0
7 /btmac vfat /dev/block/mmcblk0p5 (null) 0
8 /data ext4 /dev/block/mmcblk0p8 (null) -32768
9 /emmc datamedia /dev/null (null) 0
10 /sdcard vfat /dev/block/mmcblk1p1 /dev/block/mmcblk1 0

W:Unable to get recovery.fstab info for /datadata during fstab generation!
W:Unable to get recovery.fstab info for /sd-ext during fstab generation!
I:Completed outputting fstab.
I:Processing arguments.
I:Checking arguments.
I:device_recovery_start()
Command: "/sbin/recovery"

ro.boot.serialno=015d21d52747f40d
ro.boot.commchip_id=0
ro.boot.productid=0x02
ro.boot.carrier=wifi-only
ro.serialno=015d21d52747f40d
ro.bootmode=unknown
ro.baseband=unknown
ro.bootloader=unknown
ro.hardware=cardhu
ro.revision=0
ro.emmc=0
ro.boot.emmc=0
ro.factorytest=0
ro.secure=1
ro.allow.mock.location=0
ro.debuggable=1
persist.sys.usb.config=mtp,adb
ro.build.id=JOP40D
ro.build.display.id=cm_tf300t-userdebug 4.2.1 JOP40D eng.xplodwild.20121218.214839 test-keys
ro.build.version.incremental=eng.xplodwild.20121218.214839
ro.build.version.sdk=17
ro.build.version.codename=REL
ro.build.version.release=4.2.1
ro.build.date=Tue Dec 18 21:49:07 UTC 2012
ro.build.date.utc=0
ro.build.type=userdebug
ro.build.user=xplodwild
ro.build.host=ribs
ro.build.tags=test-keys
ro.product.model=Transformer Pad TF300T
ro.product.brand=asus
ro.product.name=EeePad
ro.product.device=tf300t
ro.product.board=cardhu
ro.product.cpu.abi=armeabi-v7a
ro.product.cpu.abi2=armeabi
ro.product.manufacturer=asus
ro.product.locale.language=en
ro.product.locale.region=US
ro.wifi.channels=
ro.board.platform=tegra
ro.build.product=tf300t
ro.build.description=WW_epad-user 4.0.3 IML74K WW_epad-9.4.3.30-20120604 release-keys
ro.build.fingerprint=asus/WW_epad/EeePad:4.0.3/IML74K/WW_epad-9.4.3.30-20120604:user/release-keys
ro.build.characteristics=tablet
ro.cm.device=tf300t
ro.carrier=wifi-only
ro.sf.lcd_density=160
ro.com.android.dateformat=MM-dd-yyyy
wifi.interface=wlan0
wifi.supplicant_scan_interval=15
ro.opengles.version=131072
persist.tegra.nvmmlite=1
ro.epad.model=TF300T
dalvik.vm.heapstartsize=5m
dalvik.vm.heapgrowthlimit=48m
dalvik.vm.heapsize=256m
dalvik.vm.heaptargetutilization=0.75
dalvik.vm.heapminfree=512k
dalvik.vm.heapmaxfree=2m
ro.rommanager.developerid=cyanogenmod
keyguard.no_require_sim=true
ro.url.legal=http://www.google.com/intl/%s/mobile/android/basic/phone-legal.html
ro.url.legal.android_privacy=http://www.google.com/intl/%s/mobile/android/basic/privacy.html
ro.com.google.clientidbase=android-google
ro.com.android.wifi-watchlist=GoogleGuest
ro.setupwizard.enterprise_mode=1
ro.com.android.dataroaming=false
ro.cm.version=10.1-20121218-UNOFFICIAL-tf300t
ro.modversion=10.1-20121218-UNOFFICIAL-tf300t
ro.config.ringtone=Orion.ogg
ro.config.notification_sound=Deneb.ogg
ro.config.alarm_alert=Hassium.ogg
dalvik.vm.lockprof.threshold=500
dalvik.vm.dexopt-flags=m=y
net.bt.name=Android
net.change=net.bt.name
dalvik.vm.stack-trace-file=/data/anr/traces.txt
init.svc.ueventd=running
init.svc.recovery=running
init.svc.mischelp=restarting
init.svc.adbd=running
service.adb.root=1

I:Checking for extendedcommand...
I:Skipping execution of extendedcommand, file not found...
I:using /data/media for /emmc/clockworkmod/backup/2013-02-28.01.08.07.
SD Card space free: 21835MB
Backing up boot image...
Incorrect mbr signatures!
Error in reading mbr!
Error while backing up boot image!I:using /data/media for /emmc/clockworkmod/backup/2013-02-28.01.08.11.
SD Card space free: 21835MB
Backing up boot image...
Incorrect mbr signatures!
Error in reading mbr!
Error while backing up boot image!I:Can't format unknown volume: /external_sd
I: