Windows Server 2008 R2 SP1:Dynamic MemoryKurt Roggen [BE]Blog: http://TryCatch.be/blogs/roggenk Blog: http://SCUG.be/blogs/SCVMM

Agenda

• Overview• Hyper-V & Dynamic Memory• Startup RAM, Maximum RAM• Memory Buffer, Memory Weight• Root Reserve

• SCVMM & Dynamic Memory

Virtualization Enhancements in Service Pack 1

Dynamic Memory RemoteFXAllocate range of memory per VM & dynamically adjust memory usage on demand.

Consistent performance & Better Manageability

Leverages the power of virtualized graphics resources and advanced codecs to achieve high fidelity.

Enables “local-like” experience for a hosted desktop

Virtual Memory (vRAM) - Static

• Fully allocated at run-time• Up to 64 GB per VM• Can only adjust vRAM when VM is offline

Dynamic Memory: What?

“Dynamic Memory enables the system to dynamically adjust

virtual machine memory usage based on demand”

Dynamic Memory: What NOT!

• Is not Overcommit• Is not Page Sharing• Is not Second Level Paging

Dynamic Memory: Advantages

• Real time sizing based on memory demand• Based on performance counters inside VM

• Usable for both server and desktop workloads• Higher VM consolidation ratios per host• Windows 7 SP1 allows 12:1 ratio (vCPU:lCPU)

Dynamic Memory: Process

• Allocate memory from Hyper-V host memory pool• VM gets memory from memory pool• As long as pool is not empty• Based on memory demand/workload

• VM gets memory from other VMs • If memory pool is empty• Based on Memory Priority/Weight

• VM releases memory to memory pool

Host Memory

Pool

VM1

VM2

VM3

VM4

VM5

Virtual Memory (vRAM) - Dynamic

• Only ‘Startup RAM’ allocated at run-time• Up to 64 GB per VM• Can only adjust vRAM when VM is offline• Windows Server 2008 R2 SP1 feature

Startup RAM & Maximum RAM

• Startup RAM• Minimum amount of memory to boot VM• Guaranteed lower memory boundary • Default: 512 MB

• Maximum RAM• Limit amount of memory• Default: 64 GB

Memory Sizing

• Controlling Memory Availability• How much memory does the VM have?• How much memory does the VM want?• The difference is the availability

• Mechanisms in place to control memory• Availability through Memory Buffer and Memory

Weight settings

Memory Buffer

• How much “free” memory should we keep in the VM?• Allows for responsiveness to ‘bursty’ workloads• Can be used for file cache“I like to configure my virtual machines so that they have ~20% free memory”

• Default: 20%

Host Memory

Pool

Put it together

Memory Buffer

Startup MemoryStartup

Memory

Memory Demand

MemoryBuffer

Maximum Memory

Memory Demand * Configured Buffer Percentage =

64 GB

512 MB

Workload

20 %

MinimumMemory

DEMO

Memory Priority/Weight

• Which VM gets the memory first, when pool is empty• Default: 5,000 (1-10,000)• The higher the weight, the higher the availability/priority

of memory

Adding/Removing Dynamic Memory• Adding Memory• Immediately when VM needs it (on demand)• Enlightened fashion• Synthetic Memory Driver (VSP/VSC Pair)

• No hardware emulation• Light weight

• Removing Memory• Unutilized memory is collected every 5 minutes• Wanted to remove memory• Ballooning is more efficient

Dynamic Memory Architecture

Windows Kernel

Guest Applications

VMBus

Hypervisor

VMMS

OSMicrosoft Hyper-V

User Mode

KernelMode

VMBus

VMWP

VID

Memory Balancer

Memory Balancer Interface

GMOMemory Manager

DM VDEV/VSP

DM VSC

Dynamic Memory Components

Windows Kernel

Supporting Guest OS• Server OS• Windows Server 2003, 2008 & 2008 R2• Any edition (Web, Standard, Enterprise, Datacenter)• 32-bit & 64-bit versions

• Desktop OS• Windows Vista and Windows 7• Only Enterprise and Ultimate editions• 32-bit & 64-bit versions

System OS Requirements

• Host OS Requirements: • Hyper-V SP1

• Guest OS Requirements: • Depends on Guest OS & OS Edition:• Integration Components (IC) and/or• QFE and/or• SP1

System OS Requirements• Host OS Requirements:• Windows Server 2008 R2 SP1• Microsoft Hyper-V Server 2008 R2 SP1

• Guest OS Requirements:• Windows Server 2003: SP2 + IC• Windows Server 2008: IC• Web/Standard: SP2 + QFE 2230887

• Windows Server 2008 R2: IC• Web/Standard: SP1

• Windows Vista: IC• Windows 7: IC

Root Reserve• Hyper-V has always had the concept of a reserve of memory that is

kept for the parent partition

• Dynamic Memory allows VMs to push up against the reserve consistently (empty pool)

• New behavior to better protect the parent partition from being starved by virtual machines

• Since SP1: Host Reserve is auto-calculated based on:• If the machine SLAT capability• Total size of host RAM• NUMA architecture

Host Reserve VM overhead Memory utilized by VMs

VM Reserve

Dynamic Root Reserve• Dynamic algorithm to determine Root Memory Reserve• Since SP1: Host Reserve is auto-calculated based on:• If the machine SLAT capability• Total size of host RAM• NUMA architecture

• Algorithm: 384 MB + 30 MB per GB of host (SLAT capable)• Example: 16 GB Hyper-V Host: 384 + 16*30 = 864 MB

• Does not take into account running agents• Virtualization Management (SCVMM)• Software & Patch Management (SCCM)• Monitoring (SCOM)• Backup (SCDPM)• Hardware Agents (Server, Storage, ...)• Anti-Virus

Static Root Reserve

• Override algorithm to determine Root Memory Reserve• Override using new registry key ‘MemoryReserve’

‘HKLM\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\Virtualization’

• Allows to reserve memory for the parent partition (REG_DWORD in MB)

• May result in less memory being available for VMs

RSAT for Windows 7 SP1

• Remote Server Administration Tools (RSAT)• OOB download at http://download.microsoft.com• KB 958830

• Includes latest Hyper-V Manager console to support• Dynamic Memory• RemoteFX

Hyper-V BPA Update

• Hyper-V Best Practices Analyzer • Addon to Server Manager

• OOB download at http://download.microsoft.com• KB 2485986

• Also supports Dynamic Memory

DM & SQL Server

• Only certain editions of SQL Server are aware of dynamically changing system memory. • SQL Server 2005 Enterprise• SQL Server 2008 Enterprise / Datacenter Editions• SQL Server 2008 R2 Enterprise / Datacenter Editions

• Support for Guest Clustering

Dynamic Memory Settings Recommendation

Startup RAM 1 GB + SQL Min Server Memory

Maximum RAM > SQL Max Server Memory

Memory Buffer % 5Memory Weight Based on performance needs

DM & Exchange Server

• Most roles are candidates for virtualisation• HUB• CAS• Edge• Mailbox

• No support for Dynamic Memory

SCVMM 2008 R2 SP1

SCVMM 2008 R2 SP1 (v2.0.4521)

• Adds support for key Hyper-V R2 SP1 features• Configuration support (VM, Templates, HW Profiles,

Live Migration, …)• Intelligent Placement support

• Dynamic Memory• Startup Memory, Maximum Memory• Memory Priority, Memory Buffer• Updated VMM PRO Packs (SCOM integration)

• RemoteFX• Maximum number of monitors• Maximum monitor resolution

Dynamic Memory: Configuration Settings

VMM PRO Tips – In the Box

• SCVMM & SCOM Integration• Using PRO-enabled SCOM management packs• Deliver PRO Tips

• “Host Performance” (Hyper-V and VMware)• CPU and Memory• VMM 2008 (CPU: 90+%, RAM: 75+%)• VMM 2008 R2 (CPU/RAM: 100% - Host Reserve

CPU/RAM)• “VM Right Sizing”• CPU and Memory (CPU: 90+%, RAM: 90+%)• Support for Dynamic Memory

Updated VMM PRO Packs

• VMM PRO management packs for “VM Right Sizing”• Located in AMD64\VirtualizationMP

SCVMM 2008 R2 SP1 Upgrade Process

• Update SCVMM Server (& Database)• Update SCOM Server (import new PRO MPs)• Update SCVMM Agents• VM Hosts• Library Servers• Self-Service Portal web servers

• Update admin workstations• SCVMM Administrator Console

For more information: System Center TechCenter

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