sdm center february 2, 2005 progress on mpi-io access to mass storage system using a storage...

SDMCenter

February 2, 2005

Progress on MPI-IO Access to Mass Storage SystemUsing a

Storage Resource Manager

Ekow J. Otoo, Arie Shoshani and Alex Sim

Lawrence Berkeley National Laboratory

SDMCenter

February 2, 2005

Objective

• To allow near-online transparent access to files on mass storage system (e.g., HPSS) from MPI applications.

• To enable existing applications to dynamically access files from MSS with little modification to the source code.

• To demonstrate the feasibility of the approach by running some applications on a Linux cluster using PVFS as the local parallel file system and

HPSS as the mass storage system

SDMCenter

February 2, 2005

MPI Application on a Cluster Accessing an MSS

ION ION ION

Proxy+ Svr

CN CN CN CN

Other MSS

Parallel File System

GridFTP

•CN – Compute Node•ION – IO Node•SRM-Proxy•SRM-Svr – SRM Server

Mass Storage System(MSS)

SDMCenter

February 2, 2005

MPI-IO-SRM Architecture

Data Intensive Applications

MPI-IO SRM

PVFS GPFS UFS XFS Other

BDB Other

ADIO

HPSS

SAM

Jasmin

Castor

High Level Accessand Control

Record Structured File Access

Low Level FileSystem Access

pNetCDF HDF5

SDMCenter

February 2, 2005

Main Functions of MpiioSrm Library

• This is a package of library functions called libMpiioSrm.a The functions callable from MPI applications are:1. MPI_Srm_proxy_init();

2. MPI_Srm_file_open(); [in place of MPI_File_open()]

3. MPI_Srm_file_close(); [in place of MPI_File_close()]

4. MPI_Srm_file_delete(); [in place of MPI_File_delete()]

5. MPI_Srm_proxy_close()

• Functions (2), (3) and (4) are the only ones that take file names as a parameter of all the MPI-IO library functions.

• These can be used to build complex execution models of an application.

SDMCenter

February 2, 2005

Dependent SRM Functions

• Functions equivalent to SRM commands are: srm_abort(); srm_copy(); srm_get(); srm_ls(); srm_mkdir(); srm_ping(); srm_put(); srm_release(); srm_remove(); srm_status();

• Parameters used in these functions are either derived from a configuration file “hrm.rc” or communicated through MPI_Info object.

SDMCenter

February 2, 2005

How to Use the Library Functions

• Requires inclusion of MpiioSrm.h for compilation and libMpiioSrm during linkage.

• After MPI_init() we call MPI_Srm_proxy_init( MPI_Comm comm, int myrank, int srm_enabled, char *proxy_host, int proxy_rank, char *fileofurls,

char fileofurl_fmt, char *srmuserid, char *hrmrcpath, MPI_Info *srminfo) ;

• The application then calls MPI_Srm_file_open(), … <Invoke any MPI_* functions for processing> MPI_Srm_file_close(), etc.

• Finally it calls MPI_Srm_proxy_close(MPI_Comm comm, int proxy_rank)

before calling MPI_Finalize();

SDMCenter

February 2, 2005

Some Special Features of MpiioSrm

• Methods of specifying data sources and targets. Simple file name – a string of characters of a directory

path and basename URLs Indirectly through a file of either

• List of source and target URLs or• List of SRM commands

• Modes for opening files: In addition to the various MPI_MODE_* of the standard

we add the mode MPI_MODE_PROPCHG_ON_CLOSEto propagate any changes on the local file to the MSS.

• An application can set modes through MPI_File_info_set() command in our case.

SDMCenter

February 2, 2005

Status of the MpiioSrm library - 1

• The current status of the library includes For SRM services, we have

• srm_abort(), srm_copy(), srm_ls(), srm_ping(), srm_status(), srm_release() and srm_remove().

For MPI-IO calling SRMs we have all five basic functions implemented, namely

• MPI_Srm_proxy_init(); MPI_Srm_file_open(); MPI_Srm_file_close(); MPI_Srm_file_delete(); MPI_Srm_proxy_close()

SDMCenter

February 2, 2005

Status of the MpiioSrm library - 2

• Test Programs The current status includes the following test

programs:• TestSRM_S1RC – Static Single Request at a time.

• TestSRM_SRSC – Static Requests with Single file

processing at a time.

• TestSRM_DRSOC – Dynamic Requests with

Sequential Processing Order.

• TestSRM_DRAOC – Dynamic Requests with

Arbitrary Processing order.

SDMCenter

February 2, 2005

Looking to the Future

• Short Term Add srm_put() and srm_get() and srm_mkdir() Improve method of communicating prefetched file with

processes using MPI’s Remote Memory Access. Release for general use.

• Long Term Address scalability, fault tolerance issues and PVFS2 – use of multiple SRM servers. Define XML schema for input file formats GUI for:

• Preparing input data files for applics• Monitor files fetched and processed by applications through

MPI’s Dynamic Process Management functions