Characteristics of parallel
Characteristics of Parallel I/O
Characteristics of Parallel vo Parallel i/o falls into one of two main categories 1. Physical decomposition 2. Logical decomposition
Characteristics of Parallel I/O • Parallel I/O falls into one of two main categories: 1. Physical decomposition 2. Logical decomposition
Characteristics of Parallel vo Physical Decomposition Beowulf clusters support this type of parallel I/O Multiple processors writing data to multiple disks IBM SPs(in some configurations) support this type Local disk at each node of vo All l/o is local-best lO nodes performance Certain number of nodes are Each process opens a unique reserved for performing 1/0 file on the local system 1/0 performance will increase Implemented with standard c or with the numbers of nodes Fortran w/o call allocated to wo Excellent method for storing Can be implemented with temporary data that do not need standard c/fortran y o calls or to be kept after the program parallel l/0 library calls executes IBM SP (in some configurations) Data from multiple processes support this type of /O can be combined at the end of the run if desired
Characteristics of Parallel I/O • Physical Decomposition – Multiple processors writing data to multiple disks – Local disk at each node • All I/O is local - best performance • Each process opens a unique file on the local system • Implemented with standard C or Fortran I/O calls • Excellent method for storing temporary data that do not need to be kept after the program executes • Data from multiple processes can be combined at the end of the run, if desired • Beowulf clusters support this type of parallel I/O • IBM SPs (in some configurations) support this type of I/O – I/O nodes • Certain number of nodes are reserved for performing I/O • I/O performance will increase with the numbers of nodes allocated to I/O • Can be implemented with standard C/Fortran I/O calls or parallel I/O library calls • IBM SP (in some configurations) support this type of I/O
Characteristics of Parallel vo Logical Decomposition Multiple processors write data to a single disk Data written to a single file Direct-access I/o in high level language terminology Data from various processes will be interleaved in the file MPl-2 implements its parallel l/o in this method Data written to multiple files Data from various processes are written to a file appended with the process rank At the end of the run the files are combined into one data file Parallel machines can have l o systems that fall in either category. It is possible to have a hybrid system that has characteristics from both categories, but these will not be discussed in this chapter
Characteristics of Parallel I/O • Logical Decomposition – Multiple processors write data to a single disk – Data written to a single file • Direct-access I/O in high level language terminology • Data from various processes will be interleaved in the file • MPI-2 implements its parallel I/O in this method – Data written to multiple files • Data from various processes are written to a file appended with the process rank • At the end of the run the files are combined into one data file • Parallel machines can have I/O systems that fall in either category. It is possible to have a hybrid system that has characteristics from both categories, but these will not be discussed in this chapter
Introduction to mP-2 Parallel/o
Introduction to MPI-2 Parallel I/O