Re: [Qemu-devel] qcow2 - safe on kill? safe on power fail?

[Avi Kivity]

Anthony Liguori wrote:
> Avi Kivity wrote:
> > Journalling is so out of fashion.  It's better to sequence the 
> > operations so that failure results in a leak instead of corruption.
>
> Since the metadata is being updated synchronously, you could probably 
> get away with a pretty simple journal.  Maybe even a single field that 
> contains the offset you are allocating which then gets reset once the 
> allocation was completed.

Why would you want to get away with a simple journal when you can get 
away without one?

It's a simple matter of allocating, making sure the allocation is on 
disk, and recording that allocation in the tables.

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.