The document discusses virtualization for database administrators. It defines key virtualization terms like hypervisor, guest, and host. It explores major virtualization platforms like VMWare and costs/benefits of virtualization. The document provides guidance on optimizing SQL Server in virtual environments, including using large memory pages, dedicating resources, and monitoring from the virtualization management layer. It warns against over-allocating resources for production databases and stresses testing I/O performance.

1. Virtualization for DBAs
Joey D’Antoni
November 5, 2011

2. About Me
 Senior SQL Server DBA at Comcast
 Blog: joedantoni.wordpress.com
 Twitter @jdanton
 Email jdanton1@yahoo.com
11/7/2011
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3. Virtualization
 Major Players
 Terms
 Costs and Benefits
 Technology
 Optimizing SQL for a Virtual Environment
 Summary

4. Major Virtualization Players

5. It seemed like a good idea at the time…

6. Server Room Sprawl
 Server sprawl
 SQL sprawl
 Power and Cooling Issues in DCs
 Broader availability of SAN storage

7. 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

8. 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

9. 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

10. Costs
 VMWare isn’t cheap
 Licensing about $25k per server for a Enterprise
plus on a decent sized server
 Licensing changed from CPU—to CPU with
memory grants, allowed 96 GB per CPU license
 Hyper-V
 Included with your Windows Server Licenses
(amount of VMs vary based on edition)
 SCOM, while not required is recommended

11. 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
 Snapshots

12. How this works…
Host
One Physical Server
Hypervisor
Guest Guest Guest

13. What does the hypervisor do?
 Manages resources between guest O/S
 Memory management
 Backups
 Failover and DR

14. VMWare Architecture

15. Snapshots

16. HA and DR

17. 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

18. 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!!!

19. Shared Environment vs Dedicated
Environment

20. 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

21. 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

22. Memory Management
 Memory can be
over allocated (but
don’t do it for
production!!!)
 Hypervisor handles
it by de-duplicating
memory.
 Host Page Files

23. Balloon Driver

24. Balloon Driver
 When hosts
comes under
memory pressure,
VMWare reclaims
memory from
guests

25. Storage

26. 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

27. I/O Concerns
 Partition alignments still matters < Windows
2008
 Work with storage team to monitor I/O—
Hypervisors can have strange I/O patterns

28. Virtual Server

29. Virtualizing SQL Server
 Use Trace Flag –T834—large pages enabled
 Set min and max memory—this will lock
SQL’s memory to prevent possible balloon
driver impact
 Follow the same storage best practices you
would for a physical box (Separate TempDB,
Data, Logs)
 Test out I/O performance before beginning

30. 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

31. 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)

32. 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

33. Questions?

34. Contact Info
 Twitter: @jdanton
 Email: jdanton1@yahoo.com
 Blog (slides): joedantoni.wordpress.com