In both setups, dCache is tolerant against failures of its data pool nodes.įiles written to dCache are immutable, meaning that once written files cannot be modified. Having an HSM attached or having the system configured to hold multiple copies of each file, means that the pool nodes can be shut down at any time. When a file is transient, all dCache client operations to the file are suspended and resumed as soon as the file is fully available.Īs the result of namespace and data separation, dCache pools can be added at any time without interfering with system operation. Internal pool-to-pool, or HSM-to-pool transfers may be caused by configuration or load-balancing constraints. dCache transparently handles all necessary data transfers between the pools and optionally between the external HSM and the pools. The location of a particular file may be on one or more dCache data servers (a.k.a data pools) as well as within the repository of external tertiary storage manager. The namespace is internally managed by a database and is interfaced to the user application via the NFS protocol and via various FTP and SRM namespace operations. dCache is a joint venture between the Deutsches Elektronen-Synchrotron, DESY, the Fermi National Accelerator Laboratory, FNAL and the Nordic Data Grid Facility, NDGF.ĭCache separates the namespace of its data repository from the actual physical location of the files. dCache can be used stand-alone or configured as disk cache front-end to a tertiary hierarchical storage management (HSM) systems ( e.g., hard disk and tape) for I/O optimization. Kerberos authenticated dcap (or kerberized dcap)ģ.2.1.5 Syntax and Examples (PNFS Not Mounted Locally)ģ.2.1.6 Syntax and Examples (PNFS Mounted Locally)ģ.2.1.7 Syntax and Examples: dcap pre-load libraryģ.2.1.8 Syntax and Examples: pnfs ''protocol''ĭ Cache is a distributed, multi-petabyte scalable disk storage system with a single rooted filesystem providing location independent file access. 2.1 UNIX commands that can be used on Chimera namespaceĢ.2.2 Create list and read directory tags on mounted namespace
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