Castor: CERN Advanced STORage Manager

Fun fact: CERN sells old data tapes as souvenirs, I got myself one of the old LHC tapes :)

A few historical additions for anybody interest:

- CASTOR at CERN had also its disk centric derivative named DPM (Disk pool manager) that helped to power the LHC computing grid for multiple decades (WLCG) before getting deprecated.

- Interestingly DPM had an architecture quite aligned with the original Google File system even if developed completely separately: (One metadata node, multiple disk node. Design to do Write-once-read-many with very partial POSIX semantics).

- The LHC computing Grid is an association of research centers with their own infrastructure. As such, they had (historically) many diffent storage systems with diffent protocols and interface.

- To unify this madness, an attempt to do a "standard" protocol was made in the 2000s: the SRM protocol (storage resources manager). In a pure XKCD fashion, it went as bad as you can imagine. It tried to rely on the tech of the time (XML, SOAP, WSDL) and is a school case of terrible protocol design (bloated, slow, weak consistency, massive server overhead, stupidly complex to implement and quite insecure). The spec are worth a read if you want a good laugh [1].

- After 20y of struggle, SRM was eventually dropped for a more pragmatic and ad hoc solution based on HTTP + xrootd [2]. EOS itself uses xrootd quite extensively. (if this did not change)

- The history of computing at CERN is globally interesting because it is a pretty good image of the evolution of computing and of the "tech fashions" associated with it.

[1]: https://sdm.lbl.gov/srm-wg/doc/SRM.spec.v2.1.1.html

[2]: https://xrootd.org/

As others have said, CASTOR has been discontinued, and replaced with CTA:

https://gitlab.cern.ch/cta/CTA

Its memory is still alive in CTA, however:

https://gitlab.cern.ch/cta/CTA/-/blob/main/catalogue/TapeSea...

And Portuguese. :)

And to keep this thread, I think our three languages should count as one, because at least 20 years ago, it was quite common to have Portuguese, Italian and Spanish mingle in several activities.

Source, ATLAS TDAQ/HLT Alumni.

Though 5PB of data is freely available via https://opendata.cern.ch/

With another 4PB available which can be processed on request to extract samples of interest: https://opendata.cern.ch/docs/lhcb-releases-service-to-acces...