1. Establishing a Service Level Agreement SLA
=tg= Thomas Grohser, NTT DATA
SQL Server MVP
SQL Server Performance Engineering
Omaha, NE 08/15/2015

2. select * from =tg= where topic =
Remark
SQL 4.21
First SQL Server ever used (1994)
SQL 6.0
First Log Shipping with failover
SQL 6.5
First SQL Server Cluster (NT4.0 + Wolfpack)
SQL 7.0
2+ billion rows / month in a single Table
SQL 2000
938 days with 100% availability
SQL 2000 IA64
First SQL Server on Itanium IA64
SQL 2005 IA64
First OLTP long distance database mirroring
SQL 2008 IA64
First Replication into mirrored databases
SQL 2008R2 IA64
SQL 2008R2 x64
First 256 CPUs & > STMT/sec
First Scale out > STMT/sec
First time 1.2+ trillion rows in a table
SQL 2012
> Transactions per second
> 1.3 Trillion Rows in a table
SQL 2014
> Transactions per second
Fully automated deploy and management
AlwaysOn Automatic HA and DR
SQL 2016
Lots of new features for security
21 Years with SQL Server
=tg= Thomas Grohser,
NTT DATA
Focus on SQL Server Security,
Performance Engineering,
Infrastructure and Architecture
New Papers coming late 2015
Close Relationship with
SQLCAT (SQL Server Customer Advisory Team)
SCAN (SQL Server Customer Advisory Network)
TAP (Technology Adoption Program)
Product Teams in Redmond
Active PASS member and
PASS Summit Speaker

3. NTT DATA in North America
20,000 professionals – Optimizing balanced global delivery
$1.6B – Annual revenues with history of above-market growth
Long-term relationships – >1,000 clients; mid-market to large enterprise
Delivery excellence – Enabled by process maturity, tools and accelerators
Flexible engagement – Spans consulting, staffing, managed services, outsourcing, and cloud
Industry expertise – Driving depth in select industry verticals
NTT DATA North America Headquarters, Plano Texas

4. Agenda
Why & When?
What & How?
Q&A

5. Why do we need SLA’s
Management and coworkers need to understand and agree to reality
Help you to request and argue the resources you need
Avoid lawsuits

6. Rule Number One! SLA first Solution later
If you already have a solution don’t agree to a SLA the solution can’t support

7. What should be in a SLA? Everything Operational requirements
Maintenance windows
Responsibilities
Dependencies
What happens if the SLA is not met

8. RPO – Recovery Point Objective
In plain English: How much data can we lose?
Samples
Your last log backup is from 12 minutes ago 12 minutes
Your last full backup is from last week 1 week
You do not have a backup all

9. RTO – Recovery Time Objective
In plain English: How much time after a failure till we have to be available again
Samples
Your restore takes 6 hours 6+ hours
Your last backup does not work you have to go to tape hours

10. Availability
Time the database is available within a period of time divided by the length of the period of time.
Don’t confuse luck with availability!
How fast to you think you can fix data corruption or human error in your database?

11. Availability
99.0 %
99.7 %
99.9 %
99.99 %
% the famous five nines %

12. Availability how long can I be offline
1 Year
Days
Hours
Minutes
Seconds
1 Month 0%
365.25
8766
525960
730.5
43830
99.0 %
3.65
87.66
5260
315576
0.30
7.31
438
26298
99.7 %
1.10
26.30
1578
94673
2.19
131
7889
99.9 %
8.77
526
31558
0.73 44
2630
99.99 %
0.88 53
3156 4
263
99.999% 5
316 26 %
0.5 32 3

13. Available Is a database available when It is online in SSMS?
I can login?
I can select data?
I can update data?
I can insert data?
I can change the schema?
… you get the idea?
And don’t get me started on defining performance

14. When is a database needed?
Is the database used on the web 24x7 or just in the office from 9 to 5 or just once a month to process payroll?
Do the availability requirements apply all the time or just during the periods its actually used?

15. Service Windows Specify times when you can service your system
The more the better
Every night from 11pm till 5am, all day Saturday and Sunday, except the weekend before the year end results are due.
First Sunday every month from 2am till 4am

16. Planned versus Unplanned
Big debate is planned maintenance part of the yearly downtime or not?
Big difference between the two cases
Make sure its clearly defined and understood

17. Monitoring availability
99.999% is equivalent to less than 5.2 minutes of outage per year or less than a 0.8 seconds per day
This requires you to do an availability check at least every 0.4 seconds otherwise you waste valuable time.
For example if you monitor every 5 minutes I can failover the database without the monitoring tool noticing.

18. Availability Having a certain availability vs. guaranteeing it.
Easy to end up with 100% availability
Hard to guarantee even 99.7

19. Differentiate between HA, DR and LR
HA … High Availability
DR … Disaster recovery
LR … Last Resort
Have different RPO and RTO values for all three cases.
Define worst case scenarios each level has to deal with

20. HA … High Availability RTO: seconds to minutes RPO: Zero to seconds
Automatic failover
HA site usually close by (< 30 miles)
Well tested (maybe with each patch or release)

21. DR … Disaster recovery RTO: minutes to hours
RPO: seconds to minutes (even hours)
Manual failover into prepared environment
DR site usually several hundred miles away
Tested from time to time

22. LR … Last Resort RTO: days to weeks
RPO: minutes to hours (even a whole day)
Rebuild system from scratch
Hardware has to be ordered
Floor space, connectivity to be rented
LR site usually on different continent and jurisdiction
Have a rough plan

23. Define worst case scenario for HA
Failure of a single component
Failure of two components (which are of a different kind)
Failure of server
Failure of multiple servers
Failure of any two components
That means you need everything at least three (3) times (not so easy for disks)

24. Define worst case scenario for DR
Human error
Failure of server
Failure of multiple servers
Partial failure of data center
Full failure of data center
Failure of multiple data centers

25. Define worst case scenario for LR
Destruction / failure of multiple datacenters
Natural disaster
Sabotage
Political incident (i.e. war, regime change)
Destruction of planet earth …

26. Outside SQL Server
Make sure you state that you depend on the underlying infrastructure and failures of that infrastructure don’t count for you!
Make sure no processes are interfering
Example: async database mirroring + failover OK for loosing data. Only one person allowed to give the OK. The guy is 3 weeks on vacation and availability is down to 94.2%

27. Dependencies Who needs this database/server
What does this server need to operate
Power
Cooling
Network
Firewall rules
Domain Controller
Other servers (linked server) …

28. Responsibilities
Who can actually make a decision for a database/server
Who owns the data
Who needs to be notified if something is wrong

29. Backup retention and granularity
How far must you be able to go back?
Hours, Days, Weeks, Months, Years
And how accurate must the restore be
I need the database restored to November 15, 2008 at 6:27…
How much time do you need for this historic restores
Test them from time to time (you need the resources and time)

30. Tips for keeping the SLA
Make sure your monitoring and alerting works
Monitor your Monitoring
Test your HA, DR, LR solutions regular and especially after every change to your infrastructure.

31. DR and LR Instructions
Keep printed copies in several places trust me your electronic documentation won’t be there when you are in a DR or LR situation

32. Summary Remember Rule Number one SLA first Solution later
If you already have a solution don’t agree to a SLA the solution can’t support
The laws of physics apply (even to the best DBA :-)

33. Questions? tg@grohser.com
THANK YOU!
Questions?