Re: crash proof / recovery from power loss

[Martin Langhoff <martin.langhoff@gmail.com>]

On Tue, Jun 23, 2009 at 11:05 PM, Sascha Silbe
<sascha-ml-devel-vcs-git@silbe.org> wrote:
> I'm going to use git as a back end for the Sugar data store / Journal. [1]
> One thing I'm worried about is how it's going to behave if a crash (e.g. power loss - no corruption) occurs.
> What can happen in such a case? Is it always recoverable and if so, how?

Git is outrageously good in keeping things sane. On that front, you
won't see any problems.

Now... there is one area where it will hurt lots: storing large binary
blobs. Git assumes that every file is very small in comparison with
available physical memory.

 - Sugar utilities already can create files larger than available
memory. Think Record.xo, etoys, etc.

 - Many sugar target platforms are _very_ memory constrained. XO-1
being the prime example.

Lots of what git does would be good in the Journal. But some of the
core assumptions are not well matched.

There are some tunables in git that might help. And maybe you can
sidestep the harder corners of the problem by having a threshold, and
handling large files separately.

hth,




m
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