CS 550. Amoeba-A Distributed Operation System by Saie M Mulay. Introduction. A Brief History 1970’s: Timesharing (1 computer with many users) 1980’s: Personal computing (1 computer per user) 1990’s: Parallel computing (many computers per user)
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Amoeba-A Distributed Operation System
Saie M Mulay
1970’s: Timesharing (1 computer with many users)
1980’s: Personal computing (1 computer per user)
1990’s: Parallel computing (many computers per user)
Local Area Network
User can be assigned 10-100 processors.
Minimum configuration for a SPARC station system
File Server: 16 MB RAM, a 300 MB disk, a SCSI tape drive.
Workstation: 8 MB RAM, monitor, keyboard, and mouse.
Pool processor: 8 MB RAM
Associated with each object is a class. Classes may contain other classes and therefore are hierarchical in nature. This inheritance creates the object interface for object manipulation such as deleting, read, write, append, etc
These calls are in the form of light weight processes.
do_operation: Client sends a request message and receives a reply: the header contains a capability for the object upon which an operation is being requested.
get_request: Server sends a request from the port specified in the message header.
put_reply: Server replies
All accesses to the network are user transparent.
All resources are regarded as objects.
All Objects are managed by servers.
The system software was to be constructed as far as possible as a collection of servers executing at user-level, on top of a standard microkernel that was to run at all computers in the system, regardless of their role
There is an extra level of mapping from symbolic, hierarchical path names to capabilities.Hence user sees local objects as public objects.
In reality directories are name/capability pairs.
Write Operation not supported. Hence files cannot be changed once they are created. Thus files can be stored contiguously resulting in efficient file storage.
All internal tables are replicated.
Directory protection using encryption key
Information cached by the directory service never gets outdated.
This map has an entry for every segment of address for a potential process. An entry contains the virtual address, segment length, segment mapping, and capability of the object from which the segment is initialized.
Stunned - When the process is being debugged.
Amoeba currently runs on the following