A Communication Module of the Parallel Operating File System

1
A Communication Module of the Parallel Operating
File System

• Jong-Hyun Cho (alfcom_at_palgong.knu.ac.kr)
• Seung-ha Lee (shalee_at_ee.knu.ac.kr)
• Dae-Wha Seo (dwseo_at_ee.knu.ac.kr)
• School of Electronic and Electrical Engineering
  Kyungpook National University, Korea

2
Introduction

• SPAX(Scalable Parallel Architecture computer
  based on X-bar network)
• Has 16 clusters maximum
• Each cluster has 8 nodes, Each node has 4
  processors
• The Xcent-Net(X-bar network) interconnects among
  clusters

3
Introduction

• MISIX(Microkernel based Single system image Unix)
• Operating System for SPAX
• Based on Chorus Microkernel
• Provides a single system image over clusters

4
Introduction

• ParFiSys
• Developed at UPM in Spain
• Parallel file system for GPMIMD(General Purpose
  MIMD)
• Executed in a user level
• TCP/IP protocol is used for IPC
• ? NOT proper for SPAX system, especially for PFS
  dealing with massive data
• ? To solve the communication overhead and improve
  the performance of file I/O in the
  MISIX environment,
• POFS(Parallel Operating File System) was
  proposed.

5
POFS Architecture
6
POFS Architecture

• POFS(Parallel Operating File System)
• Operated on the MISIX and the SPAX
• Based on Chorus IPC.
• Organization of POFS
• File Server
• provides interfaces to clients for file handling
• Block Server
• manages data blocks of files
• Partitions
• Multiple partitions which are mapped on logical
  disks in the I/O nodes
• Each partition has several subpartitions
• Data blocks of a large file are distributed over
  several subpartitions in the different block
  servers

7
File Server Block Server

• File Server
• Has a buffer cache for caching data blocks
• Prefetches data blocks from block servers
• Transfers data blocks in buffer cache to block
  server to store the data blocks
• When file server receives parallel file service
  requests from application programs
• Derives the logical address of the file from
  inodes or data blocks
• Requests data block services to the block servers
• Block Server
• Directly communicates with disks
• Processes data block service requests

8
Communication Layer of POFS

• Responsible for communications between clients
  and servers
• Transparent to upper layer
• Guarantees the scalability of PFS
• Consists of a RPC module and a communication
  module

9
RPC Module

• RPC methods are used to communicate between
  application program and file server and to handle
  service requests between the file servers and the
  block servers
• Threads are used to handle the service requests
  in both file server and block server

10
Communication Module
11
Communication Module

• Has a semantic submodule and a network submodule
• Semantic Submodule
• Receives RPC messages from upper layer and
  transfers it to server
• Transforms logical data to physical data for
  managing channels
• Creates and deletes channels
• Analyzes contents of channel
• Manages channels for data transfer
• Network Submodule
• Implemented by using Chorus IPC functions
• Responsible for receiving and sending data
• ? Network module is dependent on the
  communication environment