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