Comparison of Comparison of Distributed Distributed

Operating SystemsOperating Systems

Systems DiscussedSystems Discussed

◦Plan 9◦AgentOS◦Clouds◦E1◦MOSIX

Plan9 - 1Plan9 - 1History

◦Bell Labs 1984 – 2002 (and on)◦“Plan 9 from Bell Labs” based on

“Plan 9 from Outer Space.”

◦Replaced Unix as primary research platform. ◦Based on 9P protocol.

Accesses all resources, local and remote.

Plan9 - 2Plan9 - 2Notable architecture:

◦All system interfaces through file system. (pre-Linux)

Workstation - independent working environment

“Workstation” – aggregated resources, remote and local.

Plan9 - 3Plan9 - 3/proc

◦All processes are visible as files/net

◦All network traffic read/written through file system

Can import posix apps, emulate Berkeley socket interface through APE (ANSI/POSIX Environment)

AgentOS - 1AgentOS - 1

Originally designed by Harry Chen at UC, Irvine (1998)

Subsumed by The Bio-Networking Architecture project◦Grants from NSF, DARPA, and AFOSR (Air Force

Office of Scientific Research)

AgentOS - 2AgentOS - 2Goal: Ubiquitous Access

◦Nomadic and mobile usersBased on Java VM Agent based vs. RPC

◦Adaptive vs. dummy communicationByte code inefficiency

◦Just In Time Compilers with caching

Clouds - 1Clouds - 1History

◦Clouds is actually 2 separate operating systemsClouds V1, based on VAX kernel 1986Clouds V2, based on Ra kernel ~1989

Purpose◦Support distributed research at Georgia Institute of Technology

Clouds - 2Clouds - 2

Clouds based on the object/thread paradigm

At OS level there is only one type of object, clouds

Ra kernel implements persistent virtual memory◦Threads travel through objects◦Entry points

E1E1E1 first distributed commercially in 2005.Very much like clouds

◦Object/thread paradigm ◦Difference: Threads outside of objects

Objects replicated and synchronized◦Redundancy vs. loss of efficiency in replication

MOSIX - 1MOSIX - 1Version 0 (1977) – research project on

process migration◦based on Unix 6◦tested on PDP 11/45 and diskless 11/10

connected by parallel I/O◦Named: UNIX with satellite processors.

Current Version, 10 (2006) [MOSIX2]◦Supporting Linux Kernel 2.6

Generic Solution – dynamic management of resources.

MOSIX - 2MOSIX - 2

Core – ◦adaptive sharing algorithms◦Preemptive process migration◦Load balancing

Process placement System structure

Compatibility:◦Connect with any Linux, only one MOSIX hub required

MOSIX - 3MOSIX - 3Cluster – collection of computersGrid – collection of clustersPartition

◦Limited to 256 nodes (by IP addressing)Highly secureInfinitely scalable

Impact on Current SystemsImpact on Current Systems

Impact on current systems◦Plan9 file system in Linux◦Clouds RPC model in later UNIX and windows

◦AgentOS theory behind Google Docs