USB 3.0 external storage install

[vv329]

Hi Kith,
I have a question about persistent install on USB drive, I am not intend to carry the OS to other system and expect it will work without tweak, however I am hoping to have a music only system share the same HTPC with minimum risk of messing things up by my kids or wife... so the only safe solution is to keep the boot drive unpluged when I am not using it. I have tried the followings without success (Working beautifully if I install in on local hard disk though):

1. Full install to external USB 3.0 SSD, it stop booting after my last sudo apt-get updated, not very reliable
2. Unetbootin on USB flash drive with 8G persistent on 16G USB stick, fail to boot
3. Rufus to create image on USB stick and Casper-RW creation tool from PendriveLinux for persistent, fail to boot
4. MKUSB to create USB drive, fail to boot

I do not expect to update the kernel with this approach, just want to install and updates add-ons, Snakeoil fw etc and of course keeping my information after reboot, what is the best method?

Best regards,

William