Skip to content

Data management

Split book-keeping files

The .dst description files downloaded directly from Dirac contains a list with a large number of files (700 files or more). For example, this file contains 1690 lines: 

/lhcb/LHCb/Collision12/SEMILEPTONIC.DST/00067251/0000/00067251_00001536_1.Semileptonic.dst
/lhcb/LHCb/Collision12/SEMILEPTONIC.DST/00067251/0000/00067251_00001039_1.Semileptonic.dst
/lhcb/LHCb/Collision12/SEMILEPTONIC.DST/00067251/0000/00067251_00000344_1.Semileptonic.dst
/lhcb/LHCb/Collision12/SEMILEPTONIC.DST/00067251/0000/00067251_00000301_1.Semileptonic.dst
/lhcb/LHCb/Collision12/SEMILEPTONIC.DST/00067251/0000/00067251_00000850_1.Semileptonic.dst
/lhcb/LHCb/Collision12/SEMILEPTONIC.DST/00067251/0000/00067251_00000988_1.Semileptonic.dst
/lhcb/LHCb/Collision12/SEMILEPTONIC.DST/00067251/0000/00067251_00001423_1.Semileptonic.dst
/lhcb/LHCb/Collision12/SEMILEPTONIC.DST/00067251/0000/00067251_00000841_1.Semileptonic.dst
...
/lhcb/LHCb/Collision12/SEMILEPTONIC.DST/00067251/0000/00067251_00001096_1.Semileptonic.dst

It is impractical to download every single one of them, as we don't have enough storage space in lxplus, even with EOS.

To split, we use split, a linux tool that should have been installed by default: 

split --lines=50 <filename.txt>
In this case, the <filename.txt> will be sliced for every 50 lines, and the output filenames will be x??.

Download data files with lxplus

To download all dst files listed in a bookkeeping file: 

lhcb-proxy-init
lb-dirac dirac-dms-get-file -D <target_dir> --File <file_with_list_of_lfns>

If you know a LFN, instead of a file that contains a list of LFNs, you can: 

lb-dirac dirac-dms-get-file -D <target_dir> -l <lfn>

Query MC DDDB and CONDDB tags

Warning

MagUp and MagDown have different tags. Typically you can replace mu100 with md100.

Find the production number for a given .dst LFN, say: 

/lhcb/LHCb/Collision12/SEMILEPTONIC.DST/00067251/0000/00067251_00000841_1.Semileptonic.dst

It's production number is 67251.

On lxplus, do the following: 

lhcb-proxy-init
lb-dirac dirac-bookkeeping-production-information 67251

The output contains both DDDB and CONDDB tags.