2.0 upgrade experiences

[Martin Pool]

2009/8/13 Robert Collins <robertc at robertcollins.net>:
> On Thu, 2009-08-13 at 16:05 +1000, Andrew Cowie wrote:
>
>
>> > Also, it doesn't seem that unreasonable to me that rather than even
>> > try to work out when it is safe, we transiently use a bit more disk
>> > space that will later be collected.  So I think it's partly a problem
>> > of communication.
>>
>> Frankly, the problem is a marketing one.
>
> One thing we could do is, on upgrade:
>  - pack automatically (we do this)
>  - fsync()
>  - clean obsoleted packs.
>
> I'm comfortable with the performance hit and small loss window this
> would introduce because:
>  - upgrade is very rare (compare to 'pull' or 'commit')
>  - I only know of one consumer platform that makes fsync-not-fsync.

On upgrade we've normally already made a backup of the whole
repository so I think having it pass down a flag saying pack should
immediately remove obsolete data would be very safe.

-- 
Martin <http://launchpad.net/~mbp/>