I believe unionfs-fuse has been tried for Debian and/or Ubuntu live-CDs and was found to be too slow to be usable. Currently they are both using aufs but they will probably switch to Val's implementation when it's done.
Posted Jul 15, 2010 19:24 UTC (Thu) by aakef (guest, #38030)
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I know that performance needs to be increased and it is on my TODO list for the 2nd next version. However, you really have to compare how much time Radek and I spent on unionfs-fuse compared to the kernel attempts. It is just a lack of my time to bring it into the state where I would like to have it...
But then also on the other hand, I use unionfs-fuse my own self-made ubuntu live usb sticks and I don't see any difference in boot time and application load time between usb-stick vs. usb-stick + unionfs-fuse. I have not tried it on high speed SSDs yet (I simply don't have any).