Virtualization Fundamentals for

DBAs

Joey D’Antoni

February 3, 2015

DBA Fundamentals VC

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

Principal Consultant, Denny Cherry and Associates

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

He wants you to make sure you can restore your data

Joeydantoni.com

Virtualization

Major Players

Terms

Costs and Benefits

Technology

Optimizing SQL for a Virtual Environment

Summary

Major Virtualization Players

Virtualization

Why did it happen?

It seemed like a good idea at the time…

Server Room Sprawl

Server sprawl SQL sprawlPower and

Cooling Issues in DCs

Broader availability of SAN storage

Cloud Computing

VM Terminology

Guest—The virtual server running underneath the physical host and

hypervisor (instance of an Operating System)

Host—The physical server that your virtual machines run on

Hypervisor—The underlying software that performs the load balancing and sharing of resources between guest

operating systems

VM Terminology (cont’d)

Thin Provisioning—Allowance in virtual environments to overallocate physical resources (more to come later)

Deduplication—Process of compressing memory/disk space by saving only one copy of common bits

vMotion/LiveMigration—Process which moves guest OS’s from host with high resource utilization to lower. Also an HA function with the hypervisor

Terminology (cont’d)

Snapshot—A full point in time backup of your guest OS (very handy for upgrades/patches/code releases)

Cloning—The process of building a gold guest image in order to rapid deployment

Costs

VMWare isn’t free

Memory Based Licensing

Hyper-V

Included with your Windows Server Licenses

(amount of VMs vary based on edition)

SC-VMM, while not required is recommended

Benefits of Virtualization

Lower cooling and power

Higher utilization of hardware

Can be used for HA configurations

Rapid Deployment of new environments

Use Gold Standard servers and rollout

SQL Server Licensing

Snapshots

How this works…

Host

Hypervisor

Guest Guest Guest

One P

hysic

al S

erv

er

What does the hypervisor do?

Manages resources between guest O/S

Memory management

Backups

Failover and DR

Types of Hypervisors

Type 1—Native or Bare Metal. Run directly

on host (VMWare ESX, Hyper-V)

Type 2—Run as process on local OS.

(VMWare Workstation, Virtual Box)

VMWare Architecture

HA and DR

Typical Hardware

Virtualization hosts are the typical servers

you might run SQL Server on.

2 x 4-6 core processors (Dual socket servers

represent 80% of install base)

A Lot of RAM

Snapshots

Thin Provisioning

Allows over allocation of resources

Increases storage provisioning

Management console allows for easy management of this along with SAN

NOT GOOD FOR PRODUCTION DB SERVERS!!!

Shared Environment vs Dedicated

Environment

Multi-Tenant Environments

This can make monitoring and

baselining your server more challenging

You will want to have open

communications with your VM administrators

Ask for view access into

vCenter—it will show you what

else is going on in the environment

CPUs

Can be over allocated

Use servers with the newest chips—they are

optimized for Virtual

Workloads

Maintain 1:1 ratio of physical cores to vCPU for production

boxes

For production workloads you may want to

dedicate CPUs to the machine

Memory Management

Memory can be

over allocated (but

don’t do it for

production!!!)

Hypervisor handles

it by de-duplicating

memory.

Host Page Files

Balloon Driver

Balloon Driver

When hosts

comes under

memory pressure,

VMWare reclaims

memory from

guests

Storage

I/O Concerns

Two choices of file types—VMFS (VMWare

File System) and RDM (Raw Device

Mapping)

Performance between two is similar

RDM is required for clustering

VMFS generally more flexible

Use Shared Storage (SAN) to get HA and DR

functionality

I/O Concerns

Partition alignments still matters < Windows

2008

Work with storage team to monitor I/O—

Hypervisors can have strange I/O patterns

Datastores

• It can be easy to overwhelm

storage if not enough storage

devices are presented

• Modern SANs tend to be

designed with this in mind

Windows Server 2012

Introduces concept of “Storage Spaces”

Allows storage to be pooled and shared

between multiple VM hosts

Can be created from non Microsoft platforms

Storage Spaces

Virtual Server

Virtualizing SQL Server

Use Trace Flag –T834—large pages enabled

Reserve memory for production workloads

Also reserve memory in Hypervisor for Prod

Servers

Follow the same storage best practices you

would for a physical box (Separate TempDB,

Data, Logs)

Baseline IO performance

Virtualizing SQL Server

Think carefully about using lock pages in

memory*

Enable optimize for ad-hoc workloads

DON’T OVERALLOCATE CPUs

Monitoring SQL Server

From the server perspective everything stays

the same

Everything may not match at times

Ask for access to the vSphere client!

It’s the only way to have an overview into the

broader system

Performance Issues

Troubleshoot as you normally would, then

check VMWare

Similarly with a SAN—try to identify what you

apps are sharing your resources

Can adjust load on the fly by using vMotion

(or Live Migration)

Summary

Virtualization is the future, and the future is

now!

Virtual servers work from a shared resource

pool and that can impact your workloads

Identify changes you need to make to your

SQL Servers for Virtual Environments

Get access to your virtualization

management layer

Questions?

Contact Info

Twitter: @jdanton

Email: jdanton1@yahoo.com

Blog (slides): joedantoni.wordpress.com