Borg Architecture Quiz and Flashcards: Borglet System Overview

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Questions and Answers

What happens to a Borglet if it does not respond to several poll messages?

It restarts automatically

It is marked as down and tasks are rescheduled on other machines (correct)

It loses all its data

It is marked as up and continues to run tasks

What is the primary function of the Fauxmaster?

To debug failures by interacting with a simulated Borgmaster (correct)

To manage state machines for objects in the system

To schedule tasks in a Borg cell

To handle client RPCs in a Borg cell

What is the primary function of the Borgmaster?

To communicate with other Borgmasters

To run tasks and services on Borglets

To manage and schedule tasks on Borglets (correct)

To store tasks and services

How do scheduler replicas operate in a cell?

They operate on a cached copy of the cell state Signup and view all the answers

How many replicas of the Borgmaster are there in a cell?

Five Signup and view all the answers

What is the minimum number of CPU cores required to run a busy Borgmaster?

10-14 CPU cores Signup and view all the answers

What is the role of the Borglet in a Borg cell?

To run on each machine in a cell Signup and view all the answers

What is the function of the scheduler in a Borg cell?

To schedule tasks and allocate resources Signup and view all the answers

What is the maximum number of machines a single Borgmaster can manage in a cell?

Thousands of machines Signup and view all the answers

What happens to tasks on a Borglet if the Borgmaster fails?

Tasks continue to run normally Signup and view all the answers

What is the purpose of the main Borgmaster process?

To handle client RPCs and provide read-only access to data Signup and view all the answers

What is the role of the Borgmaster in a Borg cell?

To manage state machines for all objects and communicate with Borglets Signup and view all the answers

What is the purpose of a Chubby lock in the Borgmaster election process?

To allow other systems to find the newly elected master Signup and view all the answers

What happens when a replica recovers from an outage in the Paxos-based store?

It dynamically re-synchronizes its state from other Paxos replicas Signup and view all the answers

What is the purpose of a checkpoint in the Borgmaster's state?

All of the above Signup and view all the answers

What is the typical time it takes to elect a new master and failover to it in a small cell?

10 seconds Signup and view all the answers

What is the purpose of Fauxmaster, a high-fidelity Borgmaster simulator?

To read checkpoint files Signup and view all the answers

What is the benefit of the Borgmaster's features for SREs?

They allow SREs to manage a few tens of thousands of machines per person Signup and view all the answers

Study Notes

Borg System

A Borglet is marked as down if it doesn't respond to several poll messages, and its tasks are rescheduled on other machines.
When communication is restored, the Borgmaster instructs the Borglet to kill rescheduled tasks to prevent duplicates.

Borgmaster Architecture

A Borgmaster consists of two processes: the main Borgmaster process and a separate scheduler.
The main Borgmaster process handles client RPCs, manages state machines, communicates with Borglets, and provides a web UI.
The scheduler is responsible for scheduling tasks and operates on a cached copy of the cell state.

Scalability

A single Borgmaster can manage thousands of machines in a cell, with arrival rates above 10,000 tasks per minute.
A busy Borgmaster uses 10-14 CPU cores and up to 50 GiB RAM.