Disk Buffer

CTA needs a fast disk buffer in front to ensure high performance. In theory, CTA is not tied into any specific disk buffer technology. At the moment, there are two major disk buffer systems that support tape workflows with CTA.

EOS

The EOS storage system was created for the extreme computing requirements at the Large Hadron Collider (LHC) at CERN. EOS stands for EOS Open Storage and started as a disk-only storage system developed since 2010 at CERN.

The CTA uses EOS as the user facing disk storage system (EOSCTA) which connects to the tape infrastructure and additional tape services.

The EOSCTA deployment consists of relatively small disk buffer with fast SSDs. The CTA users send requests to EOSCTA for archiving or retrieving files from tape. EOSCTA further contacts the CTA Frontend server which schedules the request for processing. Once a tape server mounts a tape it contacts directly EOSCTA and transfers the file either to (retrieve) or from (archive) EOSCTA.

To understand the EOS architecture in more detail please see the official EOS documentation.

dCache

See the official dCache website and its CTA plugin.