1. DR and HA 101.
What those letters mean & why they’re important to almost every business

2. Pat Phelan Wrote my first “paid” program in 1975, written on an HP-25.
Built and programmed microcomputers in the 1970s
First commercial database was IMAGE-3000 on an HP 3000.
Currently working with many databases on many platforms.
Joined DECUS in the 1970s
Regular user of Ward Christiansen’s CBBS
Active in PASS
Local Group Leader
SQL Saturday Organizer
Speak at SQL Saturdays 6-10 times per year

3. Disclosure: Pat Phelan works for Involta, LLC
Disclosure: Pat Phelan works for Involta, LLC. But he isn’t here to sell you anything.
Involta does:
Co-location
Your equipment in our data center
Private Cloud seller
We sell Vcloud and Hyper-V to clients
Public cloud reseller
Azure
AWS
Google
We provide Managed Services
Help desk
System Admin
“Last mile” cable/fiber in some areas of the country
Staff augmentation
Project/contract expertise

4. DR – Disaster Recovery
This is what helps you (the DBA) get the business back up after a meteor destroys your office, data center, etc.
DR has been around since shortly after the first disaster, probably in the 1960s
For most businesses, having a valid (working) DR plan is the difference between recovering from a disaster or not.

5. HA – High Availability
HA is an important “next step” for many businesses after DR is working
HA has been around in many ways for years such as having multiple aircraft which can become “Air Force One” on very short notice.
HA is implemented differently on computers than in other fields, but many of the ideas carry over well.
If HA is perfect, a business may not need DR. Historically, it has always been a bad idea to bet on perfection.

6. DR preparation
The first and most important step is to realize that your business needs a DR plan.
The next step, is to understand what you need to protect from disaster. Attending this session is the first step in that process!
DR is critical, it must be completed and maintained!
HA is important, but it is harder to do well and much easier to make completely successful. Work on HA after DR is done!

7. DR and HA “Nines” The “Nines” expresses the percentage of availability
One nine means 90 percent available.
The system can have over a month of unplanned downtime per year
Five nines means % available
The system can have just over five minutes of unplanned downtime per year
Each nine means changes to the system
Nines quickly become EXPENSIVE $$$
Rule of thumb, adding each nine means ten times the previous cost

8. DR and HA Terms RPO and RTO
RPO Recovery Point Objective (might be A or B)
How much data can be lost?
RTO Recovery Time Objective (might be B-G)
How quickly does something need to be back online?
RTP Return To Production (always G) A B C D E F G
Normal
Production Down
Production Restored
Secondary Online

9. DR and HA Terms RPO and RTO
RPO Recovery Point Objective (might be A or B)
How much data can be lost?
RTO Recovery Time Objective (might be B-G)
How quickly does something need to be back online?
RTP Return To Production (always G) A B C D E F G
Normal
Production Down
Production Restored
Secondary Online

10. DR Requirements Backups, backups, backups!!!
Identify “single point of failure”
Power
HVAC
Telecom
Storage
Ask your providers about single points of failure
Consider a consultant, experience and “fresh eyes” matter

11. DR Preparations Have a “getaway bag” and maintain it
Keep “safe” backups
When does a backup actually exist?
Test your “safe” backups regularly (at least monthly)
DR drills
First one
Start small
Expect the first attempt to fail
Subsequent drills
Schedule when convenient
As realistic as you can afford to make them

12. HA Planning
Every HA plan has common elements, but no two are identical
Even clouds have problems, they need HA too
AWS and Azure have both had major outages in 2019
Your secondary should not share ANYTHING with primary
If in doubt, hire a consultant who isn’t selling you anything but their services. In other words, don’t hire consultants from the company that provides your cloud to help you plan your HA

13. Pat Phelan DR and HA 101 Pat is the Database Mentor at Involta, LLC.
Twitter:
@YetAnotherSQL
SQL Saturday #886
Indianapolis, IN
August 2019