Re: High Availability and Replication

On Mar 1, 2024, at 11:36 AM, normandavis1990 <normandavis1990@proton.me> wrote:

> On Thursday, February 29th, 2024 at 11:38 PM, Israel Brewster <ijbrewster@alaska.edu> wrote:

On Feb 29, 2024, at 10:15 AM, David G. Johnston <david.g.johnston@gmail.com> wrote:

On Thursday, February 29, 2024, normandavis1990 <normandavis1990@proton.me> wrote:

What is the difference between High Availability and Replication?

The former is a goal, the later is a technique.

Perhaps more specifically: Replication is simply Replicating - or copying - the “master” database to one or more “slave” databases, generally in real-time such that the slave database clusters are replicas of the master. This is good when the master goes down, because you’ll still have one or more copies of it available, but by itself it doesn’t keep there from being an outage if/when the master goes down.

High Availability layers on top of replication to provide some means of ensuring that the database is HIGHLY available, such as an automatic failover system or load balancer. Many different options that work in many different ways are available to help meet this goal.

---

Israel Brewster
Software Engineer
Alaska Volcano Observatory 
Geophysical Institute - UAF 
2156 Koyukuk Drive 
Fairbanks AK 99775-7320

Work: 907-474-5172
cell:  907-328-9145

David J.

 

Hi,

You said "This is good when the master goes down, because you’ll still have one or more copies of it available, but by itself it doesn’t keep there from being an outage if/when the master goes down.". What does "goes down" mean?

In Replication mode, if the primary server is shut down, then the data will also be lost?