Bug#387780: initramfs-tools: power cut during update-initramfs leaves system unbootable

[Thiemo Nagel <thiemonagel@gmx.de>]

> > A power cut during update-initramfs may leave the system in an unbootable state as the old initrd.img is 
> > overwritten, but the new initrd.img is not yet completed.  (This happened to me when my laptop battery ran empty.)  
> > A simple fix would be to create the new initrd.img as a temporary file and move it to replace the old initrd.img 
> > only after image creation has been finished.  That way, the chance to have an unbootable system after a power cut 
> > would be significantly lower, restricted to situations in which the old initrd.img doesn't work anymore.
>
> A better fix would be to always keep a copy of the old vmlinuz/initrd.img pair
> or ramdisk including vmlinuz.
>
> This would solve lot of problems of this kind, and always keep one or more
> fallback to older kernels.

Absolutely.  That solution would require some more thought and work... 
;-)  As far as I have understood update-initramfs is called on many 
occasions and also possibly multiple times during a single apt-get run 
(not only kernel upgrades but also upgrades of other packages, like e.g. 
mdadm), so one would have to take some care to identify and backup the 
last known-working kernel/initrd.img pair.

Best regards,

Thiemo