1. SDM Center Coupling Parallel IO to SRMs for Remote Data Access Ekow Otoo, Arie Shoshani and Alex Sim Lawrence Berkeley National Laboratory

2. SDM Center Objectives and Goals Allow near-online access to files/data on mass storage system (e.g., HPSS), from MPI applications on a Linux cluster Access files/data from local and remote MSS with MPI applications Environment Applications on a Linux clusters having Local parallel file system (e.g., PVFS2) and Data stored on a remote mass storage system, e.g. HPSS Development of the MPI-IO-SRM library psrm.h libpsrm.a, libpsrm.so

3. SDM Center Usage Configuration MPI Applications MPI-IO-SRM Library HPSS dCache Castor DRMTRM Srm-Server MPI-IO Instrument program to make SRM calls in place of MPI-IO calls Start nameserver, DRM and TRM Run program as a normal MPI program A Local Parallel File System e.g., PVFS/GPFS

4. SDM Center What is SRM? Storage Resource Managers (SRM) are middleware components whose functions are to provide: 1) Controlled file transfers, 2) Dynamic space allocation, and 3) Dynamic file management SRM Enstore JASMine Client USER/APPLICATIONS Grid Middleware SRM dCache SRM Castor SRM Unix-based disks SRM SE CCLRC RAL

5. SDM Center Program Structure of an Instrumented MPI-IO Application … MPI_Init(); … MPI_Info_create(); MPI_Info_set(); … MPI_File_srm_proxy_init(); … MPI_File_srm_open(); … … MPI_File_srm_close(); MPI_File_srm_proxy_close(); … MPI_Finalize(); Provide information on set of files and order of files to be accessed Initiates the SRM Client Issues an srm_open to invoke library. If checks If file is local; otherwise Call SRM server Issues an srm_close to “release” the file to make space for new files

6. SDM Center Future Work Ready to use in real applications processing massively large datasets stored as multiple files on HPSS Control of pre-fetching of File Bundles Now processes files in sequence order only Future: any order based availability or by specified bundles Multi-Site File Access Access files from multiple sites in the same session File usage progress monitor View progress over the internet Scaling from clusters to support applications on MPP Extend to other parallel files systems - GPFS and Lustre Challenge is the operation of an SRM accessible from the MPP