The CTA Frontend serves the physics workflow event requests made by the disk system buffer, for example EOS or dCache, and cta-admin commands submitted by operators and automated scripts. Communication with the frontend is currently based on XRootD/SSI. However, not all disk front-ends support the SSI extensions to XRootD, which creates a constraint for sites using CTA as a tape backend. As a...
The CERN Tape Archive (CTA) scheduling system manages the workflow of archive, retrieve, and repack requests, relying on a Scheduler database (Scheduler DB) for transient metadata storage. We present the development of a new relational database (PostgreSQL) backend for the Scheduler DB. The aim is to improve the limitations of the current (object-store based) implementation. This talk will...
In 2024, the CTA Tape Daemon was updated to address issues in deployments with multiple drives per tape server. This was a first step towards a major refactoring of the daemon, as in its current state, its multi-process architecture presents problems such as logging information unrelated to the current process and inter-process communication bugs. It also causes confusion in internal...
Tape reading efficiency, defined as the ratio between the effective average data reading rate and the maximal data reading rate, is reduced by two operations the tape drive inevitably needs to do and during which it can not read any data. The first is mounting the tape containing the file into the drive, after possibly having unmounted the tape that was in it before. The second is spooling the...
During Run-3, CTA has demonstrated very high write efficiency at nominal DAQ rates. For retrieval, CTA relies on time-based colocation of data on tape, but this has proved to be much less efficient than expected. Furthermore, the ratio of tape reads to writes is expected to significantly increase during Run-4, as some LHC experiments move towards the “tape carousel” model. Two years ago, we...
CTA software development is primarily driven by the needs of the CERN experimental programme. Looking beyond Run-3, data rates are set to continue to rise exponentially into Run-4 and beyond. The CTA team are planning how to scale the software and service to meet these new challenges.
CTA is also driven by the needs of the community outside CERN. The landscape of tape archival for...
Final comments, questions and discussion.
