indeed ... a more userfriendly liveusb mods can be a good thing ...
you can raise your sugestion here:
[Input Needed] Sabayon 5 Brainstormto be considered for next sabayon major release ...
in theory sabayon liveusb is easy and a no brainer quick setup. You slap the iso to usbstick, slap the grub machinery on usbstick MBR then reboot and pray .... all things is suposed to be just like an livedvd session ... easy, not so?
custom installed progs can be done using custom iso with applications aplliance, like is slax modules ... no mistery here, a slax module is simply a squasfs iso image who, when loaded, is mounted on top of main sistem ... this is a thing that can be done in sabayon ... with little work ... a binary equo package is almost like an slax module ... binary ... compressed ... but not in squasfs format ...
then, for persistent user setings,
/etc,
/var,
/tmp and
/home, i think i picked all of it, is just a need for a separate partition with a little
aufs magic ... here sabayon setup must be a little tricky because we don't want too much write cycles to our usbstick not so?
so, here is how can be done:
1. load all usb persistent settings,
/etc,
/var,
/tmp and
/home, from usbstick as readonly branches
2. create a tmpfs in ram memory with all this persistent settings created again as readwrite branches
3. mount it on top of readonly usbstick filesystem
then use it .... and when you need to shutdown this live session, or after some time of continuos running, when that tmpfs is begining to be a little heavy and memory hungry, you do
THIS:
aufs - brsyncBrsync -- synchronize files between two aufs branches
J. R. Okajima
Let's assume a system such like this,
- aufs with only two branches
- one lower readonly branch on SSD
- one upper read/write branch on tmpfs
- using the system for a while, usage of the tmpfs grows
- you may want to reduce usage of tmpfs and regain the system main
memory
- usage of SSD never change since it is readonly, even if you remove
some larger files in aufs
- you also may want to reduce usage of SSD
- yes, it is ASUS EeePC.

In this case, I'd recommend you to try aubrsync script in aufs2-util.git
tree. It executes rsync(1) between the two branches.
SYNTAX
----------------------------------------------------------------------
aubrsync Options move | move_with_wh | copy \
mntpnt src_branch dst_branch [ options for rsync ]
generic form:
aubrsync [ -w | --wh ] [ -i | --inotify ] Options \
mntpnt cmd [ parameters for cmd ]
Options:
[ -n | --dry_run ]
[ -q | --quiet ]
----------------------------------------------------------------------
SIMPLE EXAMPLES
----------------------------------------------------------------------
1.
# mount -t aufs -o br:/rw:/ro none /u
# aubrsync copy /u /rw /ro
The script executes rsync(1) and,
- remove the whiteout-ed files in /ro
- COPY the non-whiteouted files in /rw to /ro
2.
# mount -t aufs -o br:/rw:/ro none /u
# aubrsync move /u /rw /ro
This is similar to above except COPY.
The operation 'move' removes the non-whiteouted files in /rw by rsync(1).
After rsync(1), the script finds all whiteouts in /rw and removes them
too.
After this aubrsync, /rw will be almost empty.
now, i hope you understand ... as you can see is ... real magic
when you want to make you changes persistent you simply
brsync that readonly
/etc,
/var,
/tmp and
/home settings from you readwrite memory tmpfs branch to you readonly usbstick branch... heh ... so sweet not so? you move a file from a readwrite partition to an readonly partition ... aufs magic ...
next time, when you boot, all settings should be already here, on you usbstick ...
to resume a little, you have
1. a readonly main sabayon squashfs iso image
2. on top of it an bunch of readonly custom little squashfs equo modules ala slax modules, for you custom installed applications
3. on top of it an persistent
/etc,
/var,
/tmp and
/home and so on readonly usbstick image
4. and on top of it a readwrite tmpfs ram based partition
in everyday operation, sistem files is loaded on demand only from squashfs modules to save as much as can be from you precious ram memory
all new and growing files, mainly from
/etc,
/var,
/tmp and
/home will be stored in tmpfs
from time to time to free you ram memory, you do a
brsync, and save you memory ... also, when shutdown that sabayon liveusb you do also a final
brsync ....
then ... reboot ... and work again, on another computer ... country ... planet ...
galaxy ... always, you lovely sabayon linux liveusb will be here, with you, with all settings and files already in place on that little usbstick ....
can be done? i think so! i think is not so hard ... comparing this setup with a livedvd setup we have only two extrasteps:
1. a readonly main sabayon squashfs iso image
<= is already done, and working well in livedvd setup2. on top of it an bunch of readonly custom little squashfs equo modules ala slax modules, for you custom installed applications
<=a new feature for liveusb setup3. on top of it an persistent
/etc,
/var,
/tmp and
/home and so on readonly usbstick image
<=a new feature for liveusb setup4. and on top of it a readwrite tmpfs ram based partition
<=is already done, and working well in livedvd setupon step 3 can be reused xsistence feature but extended to all liveusb setup, begining from /, not only /home ... here, for my taste, i think is too much to push all user setings in an separate xsistence iso ... if will be simply a separate partition on usbstick, that user files can be accesed more easy and more quickly from another linux distro .... just like an simple usbstick ... but can be imagined a lot of variations here, for example:
- a normal
/boot partition on usbstick, no compresion, no iso, no squasfs ..
- the main
sabayon.squasfs split in a bunch of main appliances: one
core.squasfs, hey! we have already this module! look like is
Sabayon Linux CoreCD 4.2 not so!?,

, one kde4.squasfs, one kde3.squasfs, one kernel.squasfs, one gnome.squasfs, x11.squasfs, apache.squasfs and so on .... portage and equo sets feature,
portage - User-defined Package Sets, is the key for a good and logical segmentation here ....
and so on ...
can be sabayon linux the first live distro to do all this things, ALL REQUIRED STEPS, not only a part of it?
will see ... will see ....
Gentoo Linux LiveUSB HOWTO and
wiki.sabayonlinux.org - What_is_XsistenCeis the reference documentation, of course ...
pendrivelinux.com - USB Gentoo 2007.0 installcan be considered reference documentation also ...
and then, is a lot of sabayon forum threads discussing this problem. i list all forum threads i found in order of importance, for me:
forum.sabayonlinux.org - liveCD to liveUSBforum.sabayonlinux.org - Live USB imageforum.sabayonlinux.org - Can't find the live USB tutorial anymoreforum.sabayonlinux.org - installing sabayon on a pendrive [SOLVED][Solved]forum.sabayonlinux.org - Post LiveUSB problems here.forum.sabayonlinux.org - Help-How to install Sabayon on usb HDD?