Experiences and developments of the RAL-LCG2 Tier-1 object store ECHO in Run-3 and preparing for HL-LHC

Abstract

Data storage at the UK Tier-1 facility at RAL is provided through its ECHO storage, serving the requirements for the WLGC and increasing numbers of other HEP and astronomy related communities. ECHO is a Cephbacked erasure-coded object store, currently providing in excess of 40PB of usable space, with frontend access to data provided via XRootD or GridFTP, using the libradosstriper library of Ceph. The storage must service the needs of: high-throughput compute, with staged and direct file access passing through an XCache on each workernode; data access to compute running at storageless satellite sites; and, managed inter-site data transfers using the recently adopted HTTPS protocol (via WebDav), which includes multi-hop data transfers to and from RAL’s newly commissioned CTA tape endpoint. A review of the experiences of providing data access via an object store within these data workflows is presented, including the details of the improvements necessary for the transition to WebDav, used for most inter-site data movements, and enhancements for direct-IO file access, where the development and optimisation of buffering and vector read strategies is explored.