[Unison-hackers] Asymmetric DSL and large files

[Benjamin Pierce]

It uses the same algorithm as rsync: the receiving machine makes a  
summary of the blocks in the file on its end and gives it to the  
sending maching (this must be what you're seeing, I guess), which then  
sends it the changed blocks.  There's a nice paper by Andrew Tridgell  
if you're interested in details...

      - B



On Jan 18, 2009, at 9:22 AM, Stefan Goldmann wrote:

> Hi Benjamin.
>
> <quote>
>
> Unison has to propagate the
> changes in your file *from* the machine that has the new version *to*
> the machine that doesn't, no?
>
> </quote>
>
> Yes, exactly. And the *from* machine is the distant work computer, and
> the *to*
> machine is the local home computer. Unison detects, that the work  
> computer's
> version has changed, so the changes should be propagated from
> work to home, using the 350kb/s bandwidth. Instead, somehow Unison  
> starts
> "eating up" all of the 50kb/s bandwidth from home to work. Why??  
> That's the
> wrong direction.
>
> I hope this clarifies things. :-)
>
> How does Unison determine what parts of a file have changed?
> I guess that this is the problem's root.
>
> Best wishes,
> Stefan
>
>
> Benjamin Pierce wrote:
>> Hi Stefan,
>>
>> I'm afraid I didn't really understand your question the first time,
>> and I don't really understand it now.  Unison has to propagate the
>> changes in your file *from* the machine that has the new version *to*
>> the machine that doesn't, no?  (If all you want is to make the two
>> versions the same, then you can tell Unison manually to overwrite the
>> new version with the old one, and then you'll be utilizing the  
>> network
>> in the fast direction.  But usually that's not what's wanted.)
>>
>> Best,
>>
>>     - Benjamin
>>
>>
>>
>> On Jan 17, 2009, at 8:41 AM, Stefan Goldmann wrote:
>>
>>
>>> Hello everyone,
>>>
>>> I've asked this question at the users list already, but we couldn't
>>> find
>>> an answer, so here it goes again.
>>>
>>> I have a large file, about 200MB, which I want to sync between home
>>> and
>>> work computer. My internet at home is ADSL, 50kbyte/s upload and
>>> 350kbyte/s download, my internet at work is 100MBit/s in both
>>> directions.
>>>
>>> When I trigger syncing these files from my home computer,  and the
>>> file
>>> has been changed on the work computer, then the following happens:
>>> Unison states "Propagating changes" and thats it. Nothing more  
>>> happens
>>> for a couple of minutes, and after that I aborted the process. I
>>> didn't
>>> even get the percentage display for the progress.
>>>
>>> A look into the network monitor revealed, that for the "Propagating
>>> changes" stage, Unison used the complete upload bandwidth of  
>>> 50kbyte/
>>> s,
>>> whereas the larger download direction wasn't utilized at all.
>>>
>>> Is this how it is supposed to be? Am I getting something wrong? In  
>>> my
>>> eyes it should be no problem to determine the parts that have been
>>> changed the other way round.
>>>
>>> I hope my problem's explanation is somehow clear enough. Have a nice
>>> weekend,
>>> Stefan
>>> _______________________________________________
>>> Unison-hackers mailing list
>>> Unison-hackers at lists.seas.upenn.edu
>>> http://lists.seas.upenn.edu/mailman/listinfo/unison-hackers
>>>
>>
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