XRootD Collaboration Meeting held at CERN 24-September-2014
- Dirk Duellmann (CERN)
- Andrew Hanushevsky (SLAC)
- Gerardo Ganis (CERN)
- Lukasz Janyst (CERN)
- Andreas Peters (CERN)
Generally, Release 4.0 has become a deployment failure. This is strictly due to the fact that installing R4 required that R3 be de-installed and most people wanted to be able to keep both versions to ease migration. To address this problem significant structural changes are being made to R4.1 to support co-existence of multiple previous major releases. This generally means that plug-in shared libraries will now be versioned as well and that we forbid linking against plug-in libraries, as there really is no reason to do so (i.e. they can only be dynamically loaded).
The rule is that Rn.x also installs the libraries for R(n-1).x for backward compatibility for existing binaries. Hence, release 4.1.x will also install the R3.3.6 libraries (the most recent R3).
Scheduled for October.
ROOT & XRootD
Over the years both packages have become entangled to the extent that people are confused as to what version to ROOT goes with what version of XRootD. The ROOT team tried to solve this via static linking in release 5.34.20 but it didn’t actually work well because XRootD does not have any statics available. Hence, the the agreement was made that the ROOT team packages the appropriate version of XRootD libraries that are necessary to run ROOT and PROOF to allow the ROOT/PROOF client to run without any additional effort. They are still checking to make sure that they only use public headers to avoid any install conflicts.
There is still a desire by many people to know what ROOT version pairs up with what XRootD version. The short table is:
- Root 5.34.21 works with Xroot 3.3.6
- Root 6.02.00 works with Xroot 4.0.3
- Root 6.04.00 works with Xroot 4.1.x
Action Item: Andrew Hanushevsky will create a compatibility table with the ROOT team and post it on the XRootD web site.
The workshop will be held January 27-29, 2015 at UCSD. The url is: https://indico.cern.ch/event/330212/
The XRootD Workshop’s goal is to focus on XRootD usage not only for HEP experiments but also for communities outside of HEP. This does not replace the Federated Workshop which is likely to be held later in the year. Some relevant topics that will be covered by collaboration members would be:
- GSI Security - Gerri Ganis to present what is needed, what should be configured, and what can go wrong.
- EOS - Andreas Peters to present where XRootD fits in and how to configure it.
- R4 Client - Lukasz Janyst - how to configure the client at the local and site levels.
- Caching Proxy - Matevz Tadel - what it does and how to maximize it use.
- Ceph - Sebastien Ponce - configuration and usage.
Lukasz Janyst is scheduled to leave by end of April 2015. CERN will post a new job for XRootD position to take over Lukasz’s responsibilities.
Apple will replace OpenSSL and Kerberos with their own APIs and libraries. This directly impacts XRootD and Gerri Ganis will look into how to migrate to the new scheme. Something similar may occur in Linux, if Linux decides to use LibreSSL libraries which are likely to diverge from OpenSSL over time.