Could you send me an example of small macro reproducing this problem?
> Also, I noticed when the buffsize is bigger than the whole event series
> (so that only one buffer(Basket) per branch is used) the branch is
> NOT compressed at all. Is that intentional?
>
The current buffer in memory is not reported to be compressed by
TTree::Print.
The buffer however will be compressed when you save the Tree header on
the file.
> I also wondered what the compression levels 3-9 mean??
> I found nothing in the docu and can't see any noticeable effect.
> So why are they implemented and when/how to use them?
>
Compression levels 3->9 show little gain in space in general (this is
data
dependent). In particular, with Root trees, when branches contain
homogeneous data, the higher level compression levels will not give
additional advantages. they just take more time.
Rene Brun