Speaker
Mr
Timur Perelmutov
(FERMILAB)
Description
The Storage Resource Manager (SRM) and WLCG collaborations recently
defined version 2.2 of the SRM protocol, with the goal of satisfying
the requirement of the LCH experiments. The dCache team has now
finished the implementation of all SRM v2.2 elements required by the
WLCG. The new functions include space reservation, more advanced data
transfer, and new namespace and permission functions. Implementation
of these features required an update of the dCache architecture and
evolution of the services and core components of dCache Storage
System.
Implementation of SRM Space Reservation led to new functionality in
the Pool Manager and the development of the new Space Manager
component of dCache, responsible for accounting, reservation and
distribution of the storage space in dCache. SRM's "Bring Online"
function required redevelopment of the Pin Manager service,
responsible for staging files from the back-end tape storage system
and keeping these files on disk for the duration of the Online state.
The new SRM concepts of AccessLatency and RetentionPolicy led to the
definition of new dCache file attributes and new dCache pool code that
implements these abstractions. SRM permission management functions led
to the development of the Access Control List support in the new
dCache namespace service, Chimera. I will discuss these new features
and services in dCache, provide motivation for particular
architectural decisions and describe their benefits to the Grid
Storage Community.
Summary
SRM v2.2 concepts and functions have induced an evolution of the dCache architecture and services.
Author
Mr
Timur Perelmutov
(FERMILAB)
