Standards Body
Open Grid Forum (OGF) This is a
merger of the GGF and the EGA
Description
The GGF's Grid Storage Management
group is a collaboration between Lawrence Berkeley, Fermilab, Jefferson
lab, Rutherford Appleton, CERN, ICTP,
and INFN to define and standardise the
Storage Resource Manager, or SRM, protocol.
This is the Grid control protocol used to query and request file
access from storage systems, ranging from single disks with a few hundred
gigabytes to multi-petabyte tape robots.
Modus Operandi
The main document is the SRM 2.2 proposed
standard.
Most of the documentation were maintained outside
the OGF, partly for historical reasons.
However, relevant working documents are gradually being imported to
the group’s gridforge.
Other documents can be found in the LBL
repository. Ongoing implementation
testing activities can be found in the SRM Group Wiki.
The group is not closed. Any group
working on an SRM implementation can join this working group. Indeed, INFN oand ICTP only joined recently (2006),
after the INFN SRM implementers and this group met each other at the EGEE
conference in Pisa. More recently, the ASGC SRM implementation
interfacing to SRB
Recent activities (as of March 2008)
At the OGF22 in Cambridge,
Massachusetts, a couple of SRM
sessions were held where we investigated implementations and where they have
deviated from the standards document which dates back to 2006. These deviations arise mainly for
interoperability reasons, where the standards document has been unclear, and
are a natural part of the stabilisation of the standard. The aim is to ensure that these are
documented and explained, so the current standard accurately reflects the
current interoperating SRM 2.2 implementations. Apart from a 20 minute introduction (a subset of the GSM-WG talk in the data management session
the following day), we had a 30-slide technical
presentation which took over 2 hours to go through – the session
was very successful, with lots of input from the audience. The next step is to write up the technical
recommendations – how to help new developers meet the standard and be
interoperable, and status and discussion of the known issues.
Relevance to EGEE
The SRM protocol is the standard for interacting with storage systems from the Grid,
from a single one hundred gigabyte disk, over terabyte disk arrays, to the
largest multi-petabyte tape robots. It
is being used by EGEE, LCG, OSG, as well as many
“smaller” Grids that use the same resources. As such, the SRM protocol is an essential
part of ensuring interoperability between Grids globally.
Interoperability
In addition to the GSM-WG work,
we have contributed to the Grid Interoperability Now efforts, also in OGF
(GIN-DATA). One of the recent
high-profile highlights is that STFC (CCLRC) has achieved interoperability
between SRM and SRB, the Storage Resource Broker from SDSC which is being
used by e.g. the National Grid Service in the UK,
or TeraGrid in the US.
In addition, we have made
contributions to GLUE-WG, also an OGF activity, to help define the StorageElement entity in the GLUE 1.3 and 2.0 schemata.
Documents
EGEE Contributors
Status
As of February 2008, SRM 2.2 is about to
replace SRM 1.1 as the preferred protocol for interacting with Storage
Elements. It is already being used
widely by WLCG in the CCRC08 exercise.
We have currently some 6-8 interoperating implementations world-wide,
being run by ~102 partner sites.
SRM 1.1 will continue to be supported in the interim, until all sites
have upgraded.
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