What is an SRM

SRM's manage storage resources on the Grid.

Needed abilities/capabilities:

Managing TOTAL Storage capacity

UseCase1.1 Putting Data In Storage.

A client wants to be able to place a certain amount of data/number of files into the storage. It needs a guarantee that this operation can be successfully carried out within a given timeframe, in which the storage is not allowed to run out of resources for this purpose. The storage should be able negotiate the duration of the guarantee with the client. The storage should be able to extend the guarantee duration in negotiation with the client.

UseCase1.2 Remove Data From Storage

The client needs to be able notify the storage that certain data/files or a given reserved storage capacity is not needed anymore and that it can be given back to the storage manager.

UseCase1.3 Temporary Data Storage

The client wants to store some data only temporarily in the storage. It will want to have a guarantee that during a negotiable time, the data will be kept on storage but after the time has expired, the client expects the storage to be freed and the data removed.

Managing ONLINE Storage

UseCase2.1 Data Movement

In order to accomodate a large number of data movement requests, the storage needs to manage which data are available online at a given moment so that they can be transferred.

UseCase2.2 Low-Latency Access

In order to accomodate applications that have a need for 'fast' high-performance access, the storage needs to be able to keep requested data online for a certain amount of time. The client needs to have the guarantee that during this time the data is accessible with very low latency. The client should be able to negotiate the duration of this guarantee with the storage, and should be able to notify the storage also if the data is not needed online any longer.

Additional Use Cases

UseCase3.1 Hierarchical Namespace

A client would like to address the files stored in the SRM by a hierarchical file namespace. For this purpose the Storage URLs that identify the files for the client need to have some additional semantics (ie it's not just a string identifier). The client would like to manage the hierarchical namespace through the SRM.

UseCase3.2 Access Control

A client would like to secure the data (with or without the hierarchical namespace). Only specific users should be able to read, write and delete the data from the SRM.

UseCase3.3 First-party Transfer

In order to avoid networking and firewalling problems, the SRM should be able to initiate a transfer as a primary participant (as opposed to being controlled as a 3rd party transfer client from the exterior). In order to achieve maximal performance, the SRM would need to expose the parameters of supported transfer protocols.

.. and there are more use cases concerning

• quotas
• metadata
• monitoring
• 'other spaces'

-- PeterKunszt - 28 Sep 2005