# The first disk-based custodial storage for the ALICE experiment

- Institution: CERN
- Department: Conferences
- Speaker: Sang Un Ahn
- Year: 2021
- Language: English
- Subjects: Physics, Computer science, Earth and environment
- Source: [CERN](https://videos.cern.ch/record/3007962)
- Licence: [CERN](http://copyright.web.cern.ch)
- Who can watch: Tweens profiles and older (sources give no ratings; placed by Invisible Network from the source's own words)

We proposed a disk-based custodial storage as an alternative to tape for the ALICE experiment at CERN to preserve its raw data. The proposed storage system relies on RAIN layout -- the implementation of erasure coding in the EOS storage suite, which is developed by CERN -- for data protection and takes full advantage of high-density JBOD enclosures to maximize storage capacity as well as to achieve cost-effectiveness comparable to tape. The system we present provides 18 PB of total raw capacity from the 18 set of high-density JBOD enclosures attached to 9 EOS front-end servers. In order to balance between usable space and data protection, the system will stripe a file into 16 chunks on the 4-parity enabled RAIN layout configured on top of 18 containerized EOS FSTs. Although the reduction rate of available space increases up to $33.3\%$ with this layout, the estimated annual data loss rate drops down to $8.6 \times 10^{-5}\%$. In this paper, we discuss the system architecture of the disk-based custodial storage, 4-parity RAIN layout, deployment automation, and the integration to the ALICE experiment in detail..

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## Lectures

1. [The first disk-based custodial storage for the ALICE experiment](https://invisiblenetwork.ai/learn/cern/3007962/3132d1eba9c9), 17 min (CERN's player)