Learn more about Embarcadero database tools at: http://www.embarcadero.com/products/database-tools Nearly 80% of performance issues appear to be related to the performance of storage. In reality, only about half of those are actual bottlenecks - frequently things like missing indexes, bad database design or misuse of features can either negatively impact the performance of the storage, or make it look like the root cause of the issue. Join Microsoft MVP, Joseph D’Antoni and Embarcadero Director of Software Consultants, Scott Walz as they shed light on diagnosing your IO subsystem. In this session, you will learn: + Where to look in SQL Server to gather information + How to use Windows Performance Monitor to analyze storage performance + What a "false positive" storage problem might look like There are only so many times you can yell at the SAN admin, before they get cranky and start giving you 1GB drives, so attend this session and learn when the time is right.

1. EMBARCADERO TECHNOLOGIESEMBARCADERO TECHNOLOGIES
Is This Really a SAN Problem?
Understanding the
Performance of
Your I/O Subsystem
Joey D’Antoni
16 September 2015

2. EMBARCADERO TECHNOLOGIES
Joey D’Antoni
• Joey has over 15 years of experience with a wide variety of data platforms, in both Fortune 50
companies as well as smaller organizations
• He is a frequent speaker on database administration, big data, and career management
• He is the co-president of the Philadelphia SQL Server User’s Group
• MSCE, Business Intelligence, Database Administration
• He wants you to make sure you can restore your data
Joeydantoni.com

3. EMBARCADERO TECHNOLOGIES
Agenda
SAN and Storage Architecture
The Language of the SAN Admin
How SQL Server uses Storage
Troubleshooting Performance Issues
Summary

4. EMBARCADERO TECHNOLOGIESEMBARCADERO TECHNOLOGIES
Poll
Who Are You?

5. EMBARCADERO TECHNOLOGIES
Bottlenecks

6. EMBARCADERO TECHNOLOGIES
Memory versus Hard Drives

7. EMBARCADERO TECHNOLOGIES
Storage Area Network

8. EMBARCADERO TECHNOLOGIES
What is a SAN?
Basically a
specialized
computer for
storage
Computer,
Switches and Hard
Drives
Not a performance
device
Can be used for
redundancy and DR
purposes
Will serve many
servers—so critical
piece of your
infrastructure

9. EMBARCADERO TECHNOLOGIES
SAN Components
HBA (Fibre) Card—Connects your server to SAN via Fiber Optic cable
iSCSI Card—Ethernet Card connecting server to SAN
Switch—Either fibre or ethernet switch connecting server to SAN
SAN head unit—Controls processing, RAID levels
Disk Array—The physical array behind your SAN (a bunch of hard drives)

10. EMBARCADERO TECHNOLOGIES
SAN Terms
LUN—Logical Unit Number, but in practical terms, what your
SAN admin will call a disk that he presents to your server
Fibre Channel—Cable connection to SAN
IOPs—I/O Operations Per Second—the way your SAN admin
measures performance

11. EMBARCADERO TECHNOLOGIES
Multi-Pathing
How your SAN
admin sleeps at
night!
Make sure your
databases servers
are multi-pathed

12. EMBARCADERO TECHNOLOGIES
SAN Throughput
0 200 400 600 800 1000 1200 1400
1 GB iSCSI
4 GB FC
8 GB FC
10 GB iSCSI
Max Mb/S
Max Mb/S

13. EMBARCADERO TECHNOLOGIES
Tiered Storage (Example—EMC VMax)
Allows for dynamic moves of disk from faster to slower disks (Fibre channel to
SATA), or slower to faster (FC to SSD)
Totally dynamic, and seamless to servers
Moves data in 768k extents
Your SAN admin doesn’t know where your data is

14. EMBARCADERO TECHNOLOGIES
FAST VP
SSD SSD SSD
15K Fibre Channel 15k Fibre Channel 15k Fibre Channel
10K SATA 10K SATA 10K SATA
Log
Data

15. EMBARCADERO TECHNOLOGIES
How to Tune a SAN
Properly configure
the array
Spend lots of
money

16. EMBARCADERO TECHNOLOGIESEMBARCADERO TECHNOLOGIES
Poll
How Frequently Do You Meet
with Your SAN Team?

17. EMBARCADERO TECHNOLOGIESEMBARCADERO TECHNOLOGIES
SQL Server and Storage

18. EMBARCADERO TECHNOLOGIES
SQL Server Storage
SQL Server uses 8k pages to store data
Data is read page by page
Data is written page by page
Pages are grouped into 64k extents
I/O patterns are mixed random and sequential
Logical and Physical Reads

19. EMBARCADERO TECHNOLOGIES
Large I/O Operations in SQL Server
Checkpoints
Scans
Check DB
Transaction Logging

20. EMBARCADERO TECHNOLOGIES
Sequential Operations
Transaction Log writes
Backup
Read-Ahead

21. EMBARCADERO TECHNOLOGIES
Writing Pages to Disk
Lazy Writing
Eager
writing
Checkpoints

22. EMBARCADERO TECHNOLOGIESEMBARCADERO TECHNOLOGIES
SQL Server I/O Demo

23. EMBARCADERO TECHNOLOGIES
How to Monitor I/O in SQL Server
• DMVs
• Windows/Perfmon
• Correlate Profiler/Perfmon

24. EMBARCADERO TECHNOLOGIESEMBARCADERO TECHNOLOGIES
Poll
How Do You Monitor
Performance Over Time?

25. EMBARCADERO TECHNOLOGIESEMBARCADERO TECHNOLOGIES
Perfmon Demo

26. EMBARCADERO TECHNOLOGIES
What Perfmon Counters are Good/Bad for SQL and
SANs
• Avg. Disk Bytes/Read
• Avg. Disk Bytes/Transfer
• Avg. Disk Bytes/Write
• Avg. Disk sec/Read
• Avg. Disk sec/Transfer
• Avg. Disk sec/Write
• Disk Bytes/sec
• Disk Read Bytes/sec
• Disk Reads/sec
• Disk Transfers/sec
• Disk Write Bytes/sec
• Disk Writes/sec
• Split I/O/Sec
• % Disk Read Time
• % Disk Time
• % Disk Write Time
• % Idle Time
• Avg. Disk Queue Length
• Avg. Disk Read Queue Length
• Avg. Disk Write Queue Length
• Current Disk Queue Length

27. EMBARCADERO TECHNOLOGIES
What to Look for in SQL Server
Missing Indexes
Queries with scans
Page Life Expectancy
It is very important to baseline this data—before and after are critical

28. EMBARCADERO TECHNOLOGIES
8 Tips for DBAs
Baseline test your SAN before it gets loaded
Baseline your SQL Server Performance
Understand any changes in user workload through your baselines
Work with storage team to understand your storage environment
Be careful of SAN firmware upgrades
Don’t blame the SAN until you have all of your data in place
If performance is absolutely critical use local storage
SANs, while cool, are not magic

29. EMBARCADERO TECHNOLOGIES
Summary
Learn how the SAN works, what it does and does not do
Understand when and where SQL Server does its I/O
SANs may not measure frequently enough
Windows gives the best storage information
You need to trend this data overtime to really understand your environment

30. EMBARCADERO TECHNOLOGIES
Questions