bruno(a)wolff.to wrote on 02/13/2014 11:34:56:
On Thu, Feb 13, 2014 at 09:38:53 -0500,
John.Florian(a)dart.biz wrote:
>I just had interesting (or incredibly stupid) idea concerning the
critical
>limitation of the live overlays where the host crashes with bus
errors
>when the temporary space for the COW is exhausted. Is it possible to
use
>trim/discard support to mitigate some of the unidirectional
growth for
>when files are deleted and/or overwritten? Conceptually it seems like
it
>is a good fit, but I've not investigated the practicality.
Just
curious
>if this has been explored or if there are easily known reasons
why this
>wouldn't work.
I don't think this will help. You aren't going to recover space from the
base file system, because it never changes. As more an more packages
are updated you are going to use more space in the overlay area.
I figured as much otherwise somebody would have already done this. But my
web searches didn't seem to reveal anything so I had to ask.
Portable flash drives are getting cheaper and you might consider
getting
one large enough for a normal install and use that instead of a live
image.
Depending on how much you are installing, a 64 GB flash drive is
probably
large enough.
That won't help me where I'm looking at hundreds to thousands of embedded
nodes that have very specific use requirements for being based on a live
image. Using a live image makes them very resilient to
mutation/corruption and anybody can simply reset the hardware and have a
node back to its normal working state. You can think of this setup
behaving much like firmware, albeit with a Fedora image. :-)
I just have to ensure the workloads can never cause the overlay to become
exhausted, which is sometimes easier said than done, which is why I asked.
--
John Florian