On Dec 10, 2003, at 1:16 PM, John Peacock wrote:
> Ryan Hunt wrote:
>> As far as I was aware the only limitations in this capacity were
>> those due to
>> the berkeley bd.
>
> There is also the issue that if the individual files are very large,
> the time to produce the version delta may be so large that the system
> would have difficulty keeping up (depending on the speed of the
> changes). Scaling has a lot more to do with the whole process, not
> just the storage.
So does this mean that the diff is created for the entire ci, or is
each file diffed individually and then readied for ci?
>>> Unless the differences between versions are themselves significant
>>> (as
>>> opposed to just being able to extract any given version),
>> Is there any significant difference?
>
> Yes. If you only need to retrieve an arbitrary version of a file, you
> can just
> as easily copy the file off to another location (c.f. snapshots
> below). With
> source-code (i.e. non-binary), frequently the diff between versions is
> itself of
> some important (i.e. what code changed).
While the diff itself is not so much of importance the fact that only
the diff is stored is.
For example: I just checked in a change to a 1.5GB disk image that had
some minor modifications. Excluding log files which can be removed
after backup the repository grew by just over 100MB. From what I can
see of the snapshot feature this would have taken 1.5GB of space to
save the new version. I can therefore get 15 levels of history in the
same space with SVN if I have the patience to wait for a checkin that
take approximately 1 hour per Gig of original source file.
This is the time it takes on rather old and dilapidated equipment. I
am in the process of trying to order 2 proc 2GHz G5s with 4GB of RAM
with a series of 2.5TB XRaids attached for the repositories. The
expectation is that this new equipment will be even faster, though I
have not been able to benchmark it at all.
-Ryan
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Received on Wed Dec 10 23:29:41 2003