[Fedora-livecd-list] The long-awaited landing of persistence

[Patrice Guay]

Warren Togami wrote:
> Jeremy Katz wrote:
>>
>> The quick steps of how to take advantage of the functionality:
>> 1) Build a live image using the newer mkinitrd (6.0.32) in your repos
>> 2) Use the updated livecd-iso-to-disk.sh with an --overlay-size-mb=512
>> (or 1024 or whatever based on the capacity of your USB stick minus the
>> size of the ISO)
>
> if [ -n "$overlaysizemb" ]; then
>     echo "Initializing persistent overlay file"
>     OVERFILE="overlay-$( /lib/udev/vol_id -l $USBDEV )-$(
> /lib/udev/vol_id -u $USBDEV )"
>     dd if=/dev/null of=$USBMNT/LiveOS/$OVERFILE \
>         count=1 bs=1M seek=$overlaysizemb
>
> Warning!
>
> If your USB stick is vfat filesystem and $overlaysizemb is
> some number larger than your RAM, your system will swap storm and die.
> According to Ulrich Drepper this isn't dd using all RAM, but it is up to
> the filesystem implementation.  Since the OOM happens in kernel space it
> cannot OOM kill anything and recover.
>
I tried creating a 512 MB overlay file when my vfat usbkey had
only 300 MB left. The filesystem on the usbkey was no longer
useable and I had to reformat the usbkey to use it again.

--
Patrice