[Gate-users] Merging multiple root files

Marcin Balcerzyk m.balcerzyk at pluri.ucm.es
Mon Nov 2 12:39:56 CET 2009

Dear Ida.

The probable thing is a local disk system limitation. All FAT-32 related
systems have 1.8GB file size limit. Root is clever enough to create a series
of files, which are separately sensible. If you want to merge them, then
probably merging application does not recognize the divided files, not to
mention that it cannot write a large file. Solution - on Windows use NTFS
system, others - do not know. Note, that you may have a nice 64bit operating
system and a lousy 32bit file system. My Red Hat Linux uses such small
capacity file system. Other solution is to use network mounted drives to a
computer that does not have such file size limitation.  

Marcin Balcerzyk

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Today's Topics:

   1. Merging multiple root files (Ida H?ggstr?m)


Message: 1
Date: Mon, 2 Nov 2009 09:38:02 +0100
From: Ida H?ggstr?m <ida.haggstrom at radfys.umu.se>
Subject: [Gate-users] Merging multiple root files
To: gate-users <gate-users at lists.healthgrid.org>
	<ff2bc2ff0911020038u595f1216kd7b8845b77c587f4 at mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"


I have some problems with merging root files with filemerger after using
jobsplitter. Sometimes it works, but for some files  I get the error "no
latest_event_ID histogram - exit!" and no merged file of course.

I think the problem is due to the fact that for some runs I get very large
root files, so they are divided into many smaller ones. E.g. for two
splitted files I get rootOut1_1, rootOut1, rootOut1_2 and rootOut2,
rootOut2_1, rootOut2_2, as supposed to only rootOut1 and rootOut2. When
using gjm it tries to merge rootOut1 and rootOut2, which I guess don't
contain all information since they are only part of the files.

Has anyone any experience with this, or knows how to merge these type of
files? thanks!

PS. I saw similar posts from April 2008 (
http://lists.healthgrid.org/archives/gate-users/2008-April/002647.html) and
Oct 2007 (
but I could not get to any scripts or really use anything for myself.
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