---
title: "Distribution of hardware, data, control"
subject: "Distributed System"
chapter: 1
key: "semester_7/distributed_system:ds-hardware-data-control"
source: https://www.bctengineer.com/q/semester_7/distributed_system/ds-hardware-data-control
site: BCT Engineering
---

# Distribution of hardware, data, control

Distributed System · Chapter 1: Introduction

- Asked in: 2070 Asar, 2+6 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/distributed_system/ds-hardware-data-control
- Whole chapter: https://www.bctengineer.com/md/semester_7/distributed_system/chapter-1

## Question

How do you define Distributed System? Explain with the model how hardware, data and controls are distributed in the distributed system environment.

## Short answer

A distributed system is independent computers connected by a network with middleware, appearing as one system. Hardware is spread across networked sites; data is partitioned or replicated; control is cooperative through message passing, avoiding a single point of failure.

## Answer

#### Definition
A **distributed system** is a collection of independent computers, connected by a network and running distribution middleware, that appears to its users as a single coherent system. Its components communicate and coordinate their actions only by passing messages (Tanenbaum; Coulouris).

#### Distribution of hardware, data and control
A distributed system distributes three things over its nodes.

```text
   Site A              Site B              Site C
 +---------+         +---------+         +---------+
 | CPU/mem |         | CPU/mem |         | CPU/mem |
 | disk    |         | disk    |         | disk    |
 | data D1 |         | data D2 |         | D1 copy |
 | control |         | control |         | control |
 +----+----+         +----+----+         +----+----+
      |                   |                   |
 =====+===================+===================+==== network
```

1. **Distribution of hardware:** processors, memory, disks and I/O devices are located at separate sites, linked by a network. Each node is an independent computer with private memory and no shared clock. Hardware can be added or removed easily, and devices such as printers are shared.
2. **Distribution of data:** data is spread over nodes by *partitioning (fragmentation)*, where different parts are kept at different sites, and *replication*, where copies are kept at several sites to give speed and availability. A distributed file system or database gives the user a single view, and consistency protocols keep copies in step.
3. **Distribution of control:** there is no single controller. Decisions (scheduling, resource allocation, mutual exclusion, commit) are made co-operatively by many nodes using message passing. This avoids a single point of failure and bottleneck, but needs agreement algorithms and synchronisation.

Together, the distribution is kept hidden by the middleware so that the user sees one system.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What describes distribution of hardware?
   A. Processors, memory and disks at separate sites linked by a network, each with private memory and no shared clock
   B. All hardware in one machine room with shared memory
   C. One processor serving all sites
   D. Hardware sharing a single global clock
   Answer: A. Each node is an independent computer. (Key point: Distribution of hardware)

2. What two techniques distribute data over nodes?
   A. Compression and encryption
   B. Partitioning (fragmentation) and replication
   C. Caching and printing
   D. Scheduling and booting
   Answer: B. Fragmentation keeps parts at different sites; replication keeps copies for speed and availability. (Key point: Data distribution)

3. Why are copies of data kept at several sites?
   A. To use more disk space deliberately
   B. To prevent any access
   C. To give speed and availability, with consistency protocols keeping copies in step
   D. To avoid needing a network
   Answer: C. Replication improves speed and availability, at the cost of maintaining consistency. (Key point: Replication purpose)

4. What is true of control in a distributed system?
   A. One central controller makes all decisions
   B. Nodes never communicate
   C. Control is fixed in one node's clock
   D. Decisions are made co-operatively by many nodes using message passing, avoiding a single point of failure
   Answer: D. There is no single controller; agreement algorithms and synchronisation are needed. (Key point: Distribution of control)

## Related in Distributed System

- [Distributed concurrency control methods](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Adistributed-cc-methods) — Distributed System, chapter 8
- [Autonomous vs distributed system](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Aautonomous-vs-distributed) — Distributed System, chapter 1
- [Models of distributed system](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Amodels-of-ds) — Distributed System, chapter 1
- [True distributed system; middleware organisation](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Atrue-ds-middleware) — Distributed System, chapter 3
- [Lock; distributed CC; deadlock situation](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Alock-cc-deadlock-situation) — Distributed System, chapter 8
- [Context switching; distributed vs network OS](https://www.bctengineer.com/question.md?key=semester_7%2Fdistributed_system%3Acontext-switch-dos) — Distributed System, chapter 3

## Related in other subjects

- [Distributed system in big data example](https://www.bctengineer.com/question.md?key=semester_8%2Fbig_data_technologies%3Adistributed-system-example) — Big Data Technologies, chapter 1
- [Control signal types and hardware control unit](https://www.bctengineer.com/question.md?key=semester_5%2Fcomputer_organization_and_architecture%3Acontrol-signals-hardware) — Computer Organization and Architecture, chapter 3
- [Data acquisition, conversion and distribution](https://www.bctengineer.com/question.md?key=semester_6%2Fdigital_control_system%3Adata-acquisition-conversion-distribution) — Digital Control System, chapter 1, asked 9×
- [Distributed system and Hadoop](https://www.bctengineer.com/question.md?key=semester_8%2Finformation_system%3Adistributed-system-hadoop-voluminous-data) — Information System, chapter 8