Dcache is a file system that is designed to store large amounts of experimental information. This means that placing in dCache requires the results of experiments and modeling, but not the programs or presentations for which AFS is intended. To access the files, you use your own dCache protocol DCAP or any access protocol to the files of the GRID system.
The authors (dcache.org) represent the system as follows:
The goal of this project is to create a system for storing and retrieving large amounts of data distributed among a large number of heterogeneous server nodes, arranged in a virtual system with a file name tree accessible by various standard methods.
Depending on the configuration, dCache provides methods for exchanging data with servers organized in one or two levels.
It provides storage, space management, pool manipulation, replication, critical load locations and file recovery in the event of a loss.
The connection to the file storage system simulates unlimited storage space with direct access. Data exchange with tapes is automatic and transparent to the user. In addition to specific HEP protocols (SRM, gFTP), data in dCache can be accessed via NFSv4.1 (pNFS), and also through WebDAV.
Why do you need to work with dCache?
The system is used at JINR and at most other Tier’s.
DCache provides access to files, including GRID, which are logically arranged in one tree, but are physically located on different disks. Many LHC collaborations treat dCache as the primary data store.