Hello, I hope this is not an already asked question and this is the right place to post. I have a very large number of files containing histograms (~1800). Each file is less than 100 KB and I have to merge them to be further processed by an ATLAS tool. My approach was to run something like this: …

It looks like this was already addressed in the past: [image] Hadd with Trees in Root 5.32 with a large number of files ROOT Hi, I could neither find a similar topic on this board nor on Savannah. I work with OS: Ubuntu 10.10 64bit Root 5.32 and 5.32.01 I have more th…

Hi Couet, thanks for your reply. I think the issue is quite different. I am using Root 6.04 and the error I get when I try to access one of the histograms contained in the “corrupted” file is: Error R__unzip_header: error in header

[quote]Is there a limit over the number of files to be merged?[/quote]The only known limit is induced by the allowed number of file descriptor and this limit is automatically handled by hadd. [quote]Is this a known issue? [/quote]So your issue is unlikely to be known and we would need a set of file…

Hi Philippe, the whole set of file is ~1.4 GB. I have them on afs’ lxplus, are you able to access there? If yes, I can put them in a public directory, if not, what option do you suggest?

Was this problem ever solved? I have the same issue when using hadd over more than ~1000 files (each file is between 200 and 400 KB). Specifically, when I try to access any histogram in the corrupted output, I get this error: Error R__unzip_header: error in header. My workaround right now is: 1) d…

Corrupted file after hadding

ROOT

couet September 27, 2016, 6:44am 2

It looks like this was already addressed in the past: