On 4/29/2010 10:25 AM, Saturn2888 wrote:
>
>
> I noticed last night something else that seems an issue. While Rsync should 
> be faster because it doesn't have to download files, it also seems to check 
> all the previous backups for that file on that host. As you might be able to 
> tell, it's searching through at least 40 incrementals here all with 
> increasing sequential level numbers. Still, that shouldn't be so bad, but 
> each incremental I add, it's getting easier and easier to figure out why the 
> times have increased.

Yes, if you use incremental levels it has to search through all of them 
to construct the state of the last run.  With the default setting it 
would just work against the last full - so you'd copy more but search less.

> While I didn't say this in my first post, I used to have full backups on a 
> lot of machines happen frequently, like weekly or every other week. With 
> those machines only being based on just a few incrementals most of the time, 
> it left a lot of laptops free to be backed up during the day using all of the 
> available bandwidth on the machine and only needing a new full ever 30-60 
> days or so. That tied with my move to Rsyncd could very possibly have caused 
> some of these slowdown issues for both Windows and Linux hosts.

There's a tradeoff with rsync fulls in that they automatically force the 
--ignore-times option every time.   That means it must do a full read of 
the target files for a block-checksum compare and if you aren't using 
the --checksum-seed option the server side also has to uncompress the 
files and do the matching computation - even for unchanged files.  I've 
always thought it would be nice to be able to decouple these functions 
so you could do full runs that rebuild the tree as the base for the next 
more often without taking the time hit to compare old unchanged files 
every time.  But, you'd have to change the Rsync.pm file to do that.

-- 
   Les Mikesell
    lesmikesell AT gmail DOT com

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