Speaker
T. Perelmutov
(FERMI NATIONAL ACCELERATOR LABORATORY)
Description
Storage Resource Managers (SRMs) are middleware components whose function is to
provide dynamic space allocation and file management on shared storage components on
the Grid. SRMs support protocol negotiation and reliable replication mechanism. The
SRM standard allows independent institutions to implement their own SRMs, thus
allowing for a uniform access to heterogeneous storage elements. SRMs leave the
policy decision to be made independently by each implementation at each site.
Resource Reservations made through SRMs have limited lifetimes and allow for
automatic collection of unused resources thus preventing clogging of storage systems
with "forgotten" files.
The storage systems can be classified on basis of their longevity and persistence of
their data. Data can also be temporary or permanent. To support these notions, SRM
defines Volatile, Durable and Permanent types of files and spaces. Volatile files can
be removed by the system to make space for new files upon the expiration of their
lifetimes. Permanent files are expected to exist in the storage system for the
lifetime of the storage system. Finally Durable files have both the lifetime
associated with them and a mechanism of notification of owners and administrators of
lifetime expiration, but cannot be deleted automatically by the system and require
explicit removal.
Fermilab's data handling system uses the SRM management interface, the dCache
Distributed Disk Cache and the Enstore Tape Storage System as key components to
satisfy current and future user requests.
Storage Resource Manager specification is a result of international collaborative
effort by representatives of JLAB, LBNL, FNAL, EDG-WP2 and EDG-WP5.
Primary authors
D. Petravick
(FERMI NATIONAL ACCELERATOR LABORATORY)
J. Bakken
(FERMI NATIONAL ACCELERATOR LABORATORY)
T. Perelmutov
(FERMI NATIONAL ACCELERATOR LABORATORY)
