The gLite File Transfer Service

In this paper we describe the architecture and implementation of the gLite File Transfer Service (FTS) and list the most basic deployment scenarios. The FTS is addressing the need to manage massive wide-area data transfers on dedicated network channels while allowing the involved sites and users to manage their policies. The FTS manages the transfers in a robust way, allowing for an optimized high throughput between storage systems. The FTS can be used to perform the LHC Tier-0 to Tier-1 data transfer as well as the Tier-1 to Tier-2 data distribution and collection. The storage system peculiarities can be taken into account by fine-tuning the parameters of the FTS managing a particular channel. All the manageability related features as well as the interaction with other components that form part of the overall service are described as well. The FTS is also extensible so that particular user groups or experiment frameworks can customize its behavior both for pre- and post-transfer tasks. The FTS has been designed based on the experience gathered from the Radiant service used in Service Challenge 2, as well as the CMS Phedex transfer service. The first implementation of the FTS was put to use in the beginning of the Summer 2005. We report in detail on the features that have been requested following this initial usage and the needs that the new features address. Most of these have already been implemented or are in the process of being finalized. There has been a need to improve the manageability aspect of the service in terms of supporting site and VO policies. Due to different implementations of specific Storage systems, the choice between 3rd party gsiftp transfers and SRM-copy transfers is nontrivial and was requested as a configurable option for selected transfer channels. The way the proxy certificates are being delegated to the service and are used to perform the transfer, as well as how proxy renewal is done has been completely reworked based on experien