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Installing xrootd

As explained in the Building ROOT page, ROOT provides the possibility to automatically build XRootD as part of the build process via the switch builtin_xrootd:


cmake -Dbuiltin_xrootd=ON <other-cmake-options>


If for some reason builtin xrootd does not work or if still using classic configure or whenever for any other reason an external XRootD is required, then you can follow the instructions below to install XRootD and to configure ROOT to use the freshly installed XRootD.

Xrootd source tarballs and binaries for some platforms can be downloaded from the xrootd web site. Version 3.1.0 (or newer) can be built and installed using the dedicated script distributed with ROOT under build/unix. Note that, starting with version 3.1.0, xrootd support has been restricted to unix platforms only, i.e. Windows support has been dropped.   

The following of this section is structured in:

Using the $ROOTSYS/build/unix/ script

The build/unix/ script understands many switches but the only one which is mandatory is the installation directory. This directory must be writable by the user running the script. If you chose to install under a system directory, e.g. /opt/xrootd, you have two options:

  • run the script under 'sudo'
    sudo build/unix/ /opt/xrootd
    (or acquire privileges with 'sudo su');
  • change the ownership of the chosen directory according to your identity. For example, to install under /opt/xrootd make sure to run the following before running the script:
    sudo mkdir -p /opt/xrootd
    sudo chown $USER /opt/xrootd
    build/unix/ /opt/xrootd

Additional configuration switches

The script allows to a few other inputs relevant to the build process. The only mandatory argument is the directory where to install the binaries, libraries, man pages and utility stuff. This installdir is not prefixed by any switch. The full list of additional, optional switches can be obtained with '-h' or '--help':

  Script to install a given version of Xrootd/Scalla
   ./ <installdir> [-h|--help] [-d|--debug] [-o|--optimized]
                      [-v <version>|--version=<version>]
                      [-t <tarball>|--tarball=<tarball>]
                      [-b <where-to-build>|--builddir=<where-to-build>]
   <installdir>: the directory where the bin, lib, include/xrootd, share and
                 man directories will appear
                 (see also --vers-subdir)
   -b <where-to-build>, --builddir=<where-to-build>
                 directory where to build; default /tmp/xrootd-<version>
   -d,--debug    build in debug mode (no optimization)
   -h, --help    print this help screen
   -o,--optimized build in optimized mode without any debug symbol
   -t <tarball>, --tarball=<tarball>
                 full local path to source tarball
   -v <version>, --version=<version>
                 version in the form x.j.w[-hash-or-tag] ;
                 current default 3.1.0
                 additional configuration options to xrootd
                 (see xrootd web site)
                 install in <installdir>/<version-root><version> instead of
                 <installdir> directly; helps separating different versions
                 under the same <root-installdir>; if <version-root> is not
                 specified, 'xrootd-' is used.
  When relevant, the script uses 'wget' ('curl' on MacOsX) to retrieve
  the tarball

The switches have the following meaning:

  • -v, --version=version-string
    Define the version to be built; this is used to determine the name of the tarball to be downloaded if not specified otherwise;
  • -t, --tarball=tarball-path 
    Define the tarball to be built; it can be the path to a local file or the URL to download;
  • -d, --debug 
    Build xrootd in debug mode;
  • -b, --builddir=build-directory
    Directory where to configure and compile; default is /tmp/xrootd-;
  • -h, --help
    Print the help screen;
  • --xrdopts="xrd-opt1 xrd-opt2 ..." 
    List of additional options to be passed to 'cmake' when configuring the built.
  • --vers-subdir[=version-root
    Install in installdir/version-rootversion-string instead of installdir directly; helps separating different versions under the same root-installdir; if version-root is not specified, 'xrootd-' is used, i.e. by passing '--vers-subdir' the installation will be in installdir/xrootd-version-string  .

Configuring ROOT with an external XROOTD

Once the script finished successfully you have to tell ROOT to enable xrootd:

cmake -Dxrootd=ON <other-cmake-options>

if xrootd is NOT installed in standard paths (/opt/xrootd, /usr/local, /usr) or if the environment variable XRDSYS is not defined to point to the installation directory, then you have to tell ROOT where to find xrootd:

cmake -Dxrootd=ON -DXROOTD_ROOT_DIR=<xrootd-install-dir> <other-cmake-options>

Configuring ROOT with an external XROOTD with classic configure

In the case of configure classic, the relevant switches are:

  • Use the '--with-xrootd' switch in ROOT configure:
    ./configure [architecture] --with-xrootd=<xrootd-install-dir> <other-configure-options>
  • If the xrootd is installed in standard paths (/opt/xrootd, /usr/local, /usr) or if the environment variable XRDSYS points to the installation directory, then you can just run
    ./configure [architecture]  <other-configure-options>
  • Use the '--with-xrootd-incdir=' and '--with-xrootd-libdir=' switches in ROOT configure when the chosen installation paths are such that they cannot be derived from a common one in a simple way (this may be the case of experiment specific installations):
    ./configure [architecture] --with-xrootd-incdir=<dir-with-XrdVersion.hh> --with-xrootd-libdir=<dir-with-libXrdClient> <other-configure-options>
    The include directory to be given is the one containing XrdVersion.hh ; the library directory is the one containing libXrdClient (the libraries needed to build depend on the version and are checked by the configure script).

Setting the environment to run with an external XROOTD

To run the paths pointing to the xrootd binaries and libraries need to be available in PATH and LD_LIBRARY_PATH (and DYLD_LIBRARY_PATH on MacOsX). To help doing this two scripts have been made available under $ROOTSYS/bin, and setxrd.csh for bash and csh shells, respectively. The scripts are to be sourced with argument the installation directory:

source bin/ <xrootd-installation-dir>
Note that these scripts set also the variable XRDSYS to point to the installation directory. Therefore, if sourced before running configure (e.g. just after running, then configure should pickup the wanted xrootd automatically, as mentioned above.

Installing the RPMs from the XROOTD official side

The XROOTD team provides binaries under RPM form for the relevant Scientific Linux compatible platforms. The relevant repo files to be used with YUM are available from the download page. XrootD is also availble in EPEL. In order to build correctly the ROOT components requiring XROOTD, i.e. netx, proofx and proofd, installation of the following RPMs are required: