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 PlayersTermsCosts and BenefitsTechnologyOptimizing SQL for a Virtual EnvironmentSummary

Major Virtualization Players

Virtualization Why did it happen?

It seemed like a good idea at the time…

Server Room Sprawl Server sprawlSQL sprawl Power 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 powerHigher utilization of hardwareCan be used for HA configurationsRapid Deployment of new environmentsUse Gold Standard servers and rolloutSQL Server LicensingSnapshots

How this works… Host Hypervisor Guest One Physical Server

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

 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    Blog (slides): joedantoni.wordpress.com