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Virtualization Fundamentals for
DBAs
Joey D’Antoni
February 3, 2015
DBA Fundamentals VC
Joey D’Antoni
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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 sprawl
Broader
availability of
SAN storage
Power and
Cooling
Issues in DCs
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…
One Physical Server
Host
Hypervisor
Guest
Guest
Guest
What does the hypervisor do?
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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
Ask for view
access into
vCenter—it will
show you what
else is going on in
the environment
You will want to
have open
communications
with your VM
administrators
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: [email protected]
 Blog (slides): joedantoni.wordpress.com