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High Availability Database Challenges

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What do we mean when we

talk about database systems &

database platform availability

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What does it mean to think about High Availability, is there a silver bullet or is it a lot more complex that that..

Is it uptime ( i.e. five 9’s )

What about service level agreements

Load balancing & Fault tolerance

Active / Standby or Active / Active

Multiple servers & storage

Redundant replicated networks & datacenters

Are we talking about N+1

No single point of failure

What do we mean by High Availability

!?

@dez_blanchfield

When we talk about database availability we usually end up talking about percentages in nines..

One Nine = (90%) = 36.5 days downtime p/yr

Two nines (99%) = 3.65 days downtime p/yr

Three nines (99.9%) = 8.76 hours downtime p/yr

Four nines (99.99%) = 52.56 mins downtime p/yr

Five nines (99.999%) = 5 .26mins downtime p/yr

Six nines (99.9999%) = 31.5 seconds downtime p/yr

What difference can a single nine make

%

@dez_blanchfield

There is no single silver bullet

when it comes to availability,

and one size does not fit all

@dez_blanchfield

AvailabilityA measure of the time that a server or process functions normally for general

usage, as well as a measure of the amount of time that the recovery process

requires after a component failure.

High AvailabilitySystem design and implementation that achieves system and data availability

almost all of the time, 24 hours a day, 7 days a week, and 365 days a year. High

availability does not equate to 100% availability. To achieve 100% availability is not

a cost-effective reality for the large majority of implementations today; rather, it is

a goal.

Availability In A Plain English Definition

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Cost & Complexity VS Type of service being delivered..

Availability VS Types of Service

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The tradeoff balance between High & Continuous availability..

Investment VS Return in Availability

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Mean Time Between Failure

Or

Mean Time To Recover

@dez_blanchfield

When it comes to database and supporting infrastructure High Availability, everyone has their own needs and wants..

What can your organisation afford

What can your business support

What skills & technology do you have in-house

Can you outsource some of the challenge

What type of market or customer are you servicing

Meeting product / service / industry norms

On-prem / externally hosted / in the cloud

My Availability is not Your Availability

!!

@dez_blanchfield

Matching desired or required

availability with performance &

business needs is no mean feat, it

takes time effort & money