Saturday, June 18, 2011

Things you should know about the Ubuntu's new Hybrid ISO

Recently, Ubuntu started making Hybrid ISOs. It's an ISO that can be burned onto a CD as usual, but also can be copied to a USB key and used as a LiveUSB without the help of Startup Disk Creator. It's just in so currently only the daily images are built that way.

But, there's some differences that you might want to be aware of before jumping on the bandwagon.

It's both a CD and regular disk image all rolled into one. Naturally, it's not persistent. Even after copying onto a USB key, it behaves like a LiveCD. Reboot and any changes you've made are lost. Copying it over to a USB key also isn't as user friendly as it sounds depending on who the "user" is. You need to use the dd command to write the image onto a USB key. It's not a matter of just copying the contents over.

How to copy the image to a USB key? Here's how:

~$ sudo dd if=oneiric-desktop-i386.iso of=/dev/sdc

I'm assuming sdc is the USB key here. Replace it with the appropriate one for your particular system (sdb, sdd, etc...). It might take a while to finish copying.

Since hybrid ISOs are new to Ubuntu, they're not yet available for all architectures. Currently, only the x86 and x86_64 architecture images are built this way.

After taking the LiveUSB for a short run, it's quite clear it behaves more like a LiveCD than the regular LiveUSB made with Startup Disk Creator. While everything may appear the same (except for persistence, of course) the LiveUSB made by copying the image, like the LiveCD, waits on you when you shutdown or reboot. If this had been made with Startup Disk Creator, it wouldn't have bothered waiting.