[One (M8) Android Development] donmarkoni:
Hahaha... :laugh: Don't get me wrong, I like TWRP, I like "the other guys", trying different approach, building from the ground up, but there was few reports of backups done by it were faulty, smaller then should have been and damaged, couldn't been restored... That is a reason I'm against it. Recovery has to work every time.

There was a guy, can't remember who, maybe he reads this and says hello, like that other time in M7 threads when I mentioned this.

About ART/Dalvik, here is what I tried..

Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.

F:\M8\fastboot>adb devices
* daemon not running. starting it now on port 5037 *
* daemon started successfully *
List of devices attached
SH44XXXXXXXX device

F:\M8\fastboot>adb shell getprop persist.sys.dalvik.vm.lib
libart.so

F:\M8\fastboot>rem reboot to bootloader

F:\M8\fastboot>fastboot devices
SH44XXXXXXXX fastboot

F:\M8\fastboot>fastboot flash recovery philz_touch_6.26.6-m8.img
sending 'recovery' (12846 KB)...
OKAY [ 1.219s]
writing 'recovery'...
OKAY [ 0.453s]
finished. total time: 1.688s

F:\M8\fastboot>rem reboot to system

F:\M8\fastboot>adb devices
List of devices attached
SH44XXXXXXXX device

F:\M8\fastboot>adb shell getprop persist.sys.dalvik.vm.lib
libart.so

F:\M8\fastboot>rem reboot to bootloader

F:\M8\fastboot>fastboot devices
SH44XXXXXXXX fastboot

F:\M8\fastboot>fastboot flash recovery openrecovery-twrp-2.7.0.2-m8.img
sending 'recovery' (14818 KB)...
OKAY [ 1.391s]
writing 'recovery'...
OKAY [ 0.500s]
finished. total time: 1.891s

F:\M8\fastboot>rem reboot to system

F:\M8\fastboot>adb devices
List of devices attached
SH44XXXXXXXX device

F:\M8\fastboot>adb shell getprop persist.sys.dalvik.vm.lib
libart.so

F:\M8\fastboot>rem reboot to bootloader

F:\M8\fastboot>fastboot devices
SH44XXXXXXXX fastboot

F:\M8\fastboot>fastboot flash recovery philz_touch_6.26.6-m8.img
sending 'recovery' (12846 KB)...
OKAY [ 1.219s]
writing 'recovery'...
OKAY [ 0.453s]
finished. total time: 1.672s

F:\M8\fastboot>fastboot erase cache
erasing 'cache'...
OKAY [ 0.078s]
finished. total time: 0.078s

F:\M8\fastboot>rem different aproach ;)

F:\M8\fastboot>rem reboot to recovery

F:\M8\fastboot>adb devices
List of devices attached
SH44XXXXXXXX recovery

F:\M8\fastboot>adb shell getprop persist.sys.dalvik.vm.lib
libdvm.so

F:\M8\fastboot>rem haha... look at that now!

F:\M8\fastboot>rem reboot to system

F:\M8\fastboot>rem ...or am I being stupid...?

F:\M8\fastboot>rem recovery is small android by itself...

F:\M8\fastboot>adb devices
List of devices attached
SH44DWM00366 device

F:\M8\fastboot>adb shell getprop persist.sys.dalvik.vm.lib
libart.so

F:\M8\fastboot>rem yes... I'm being stupid...

F:\M8\fastboot>rem going for my morning coffee...

F:\M8\fastboot>rem [some time passed] :)

F:\M8\fastboot>rem reboot to bootloader

F:\M8\fastboot>fastboot devices
SH44XXXXXXXX fastboot

F:\M8\fastboot>fastboot flash recovery openrecovery-twrp-2.7.0.2-m8.img
sending 'recovery' (14818 KB)...
OKAY [ 1.391s]
writing 'recovery'...
OKAY [ 0.484s]
finished. total time: 1.891s

F:\M8\fastboot>rem reboot to recovery

F:\M8\fastboot>adb devices
List of devices attached
SH44XXXXXXXX recovery

F:\M8\fastboot>adb shell getprop persist.sys.dalvik.vm.lib
libdvm.so

F:\M8\fastboot>rem yes, recovery uses dalvik

F:\M8\fastboot>rem reboot to system

F:\M8\fastboot>adb devices
List of devices attached
SH44XXXXXXXX device

F:\M8\fastboot>adb shell getprop persist.sys.dalvik.vm.lib
libart.so

F:\M8\fastboot>rem system remained in ART

F:\M8\fastboot>

Oh, and BTW, could you point me to the version of TWRP you are using, actual download location? Well, if you want me to try that cake you are so fond of... ;) Thanks mate! :)

Let me answer you by a question: do you know how large is system.img ???