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SE and Data Storage

User data are stored for long term persistence in one or more SEs (Data Replicas) using the Replica Manager middleware utilities. The user API is the same for LCG and EDG2 but the underlaying software differs. LCG-1 uses MDS while EDG2 uses R-GMA. The following tables report Data Management Tools and related terms.


Data Management Tools
Name (*) Action
Grid Wide Tools
edg-replica-manager (edg-rm) copy, replicate, register files
edg-replica-optimization evaluate file access cost (ROS)
edg-local-replica-catalog (edg-lrc) browse and maniputale LRC catalogue
edg-replica-metadata-catalog (edg-rmc) browse and maniputale RMC catalogue
SE Wide Tools (low level) (**)
edg-gridftp-exists check if file or directory exists
edg-gridftp-ls list SE directory
edg-gridftp-mkdir create directory on SE
edg-gridftp-rename rename file on SE
edg-gridftp-rm remove file on SE
edg-gridftp-rmdir remove directory on SE
(*) - The command abbreviated form is enclosed in brackets
(**) -Use low level tools with care to avoid corrupting the Replica Catalogue



Replica Manager Terms
Term Meaning
TURL transfer URL
SRM Storage Resource Manager
ROS Replica Optimisation Service Optor (file access cost)
RLS Replica Location Service (edg-rls) maintains information about physical
  locations of logical identifiers; components are RLI and LRC
RM Replica Management Reptor
SPI Software Process and Infrastructure
LCN Logical Collection Name
LRC Local Replica Catalogue that stores GUID to LFN mappings for a single site
RLI Replica Location Index that stores GUID to LRC and allows distributed
  access to LRC (not deployed yet)
RMC Replication Metadata Catalogue that maps LFN aliases to GUID
  together with attributes
SFN Storage File Name locates a physical file;
  it is a URL of type sfn on a valid srm host
GUID ID of a file in the SE, this is the item used by the system
  to access physical files, the GUID is immutable
UUID Universally Unique ID
LFN Logical file name, a human readable user defined name for a file,
  mapped by the system into a GUID



next up previous contents
Next: Managing Data with edg-rm Up: Grid Experience using EDG2 Previous: File Naming Conventions   Contents
luvisetto 2003-12-17