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

2. Agenda Overview Hyper-V & Dynamic Memory Startup RAM, Maximum RAM Memory Buffer, Memory Weight Root Reserve SCVMM & Dynamic Memory

3. Virtualization Enhancements in Service Pack 1

4. Virtual Memory (vRAM) - Static Fully allocated at run-time Up to 64 GB per VM Can only adjust vRAM when VM is offline

5. Dynamic Memory: What? “Dynamic Memory enables the system to dynamically adjust virtual machine memory usage based on demand”

6. Dynamic Memory: What NOT! Is not Overcommit Is not Page Sharing Is not Second Level Paging

7. External Page Sharing How it works: 1.Hash all memory and store it in a table… 2.Identify the common hashes and then… 3.Perform a bit by bit comparison What VMware doesn’t tell you… Page Sharing not dynamic Can take hours to share pages The largest benefit are zero pages Doesn’t work with large pages

8. Second Level Paging Many problems: Swapping Guest Kernel Resources Double Paging Disks are slow But it always works…

9. Other Techniques Guest directed page sharing Memory compression And on… We will continue to invest here and work on identifying the best techniques for customer work loads

10. 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)

11. 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

12. 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

14. 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

15. 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

16. 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%

17. Host Memory Pool Put it together Memory Buffer Startup Memory Memory Demand Memory Buffer Maximum Memory Memory Demand * Configured Buffer Percentage = 64 GB 512 MB Workload 20 % Minimum Memory

18. DEMO

20. 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

21. 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

22. Dynamic Memory Architecture Windows Kernel Guest Applications VMBusVMBus Hypervisor VMMSVMMS OS Microsoft Hyper-V User Mode Kernel Mode VMBusVMBus VMWPVMWP VIDVID Memory Balancer Memory Balancer Interface GMO Memory Manager GMO DM VDEV/VSP DM VSC Dynamic Memory Components Windows Kernel

23. DEMO Adding/Removing Memory Memory Weight

24. 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

25. 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

26. 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

27. 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

28. 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

29. 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

30. Root Memory Reserve(d) Different behavior in 2008 R2 RTM and 2008 R2 SP1 2008 R2 RTM The cluster property, RootMemoryReserved, watches host memory reserve level during VM startup Prevent crashes and failovers if too much memory is being committed during VM startup Sets the Hyper-V registry setting, RootMemoryReserve (no ‘d’) across all nodes Cluster default: 512 MB, max: 4 GB PS > (get-cluster ).RootMemoryReserved=1024 2008 R2 SP1 Hyper-V will use a new memory reservation setting for the parent partition memory reserve Based on “memory pressure” algorithm Admin can also configure a static reserve value The cluster nodes will use this new value for the parent partition Configuring RootMemoryReserved in the cluster does nothing

31. Changes to NUMA management Dynamic memory can result in more virtual machines spanning NUMA nodes A virtual machine might allocate ‘Startup Memory’ on one node – but added memory might come from another node New option to disable NUMA node spanning

32. What is “NUMA”? A NUMA computer: Computer CP U BUS Memory VM Back Channel Memory BUS Node 1Node 2

33. Why do I care? VM memory should come from the “local NUMA node” Computer CPU BUS Memory VM Back Channel Memory BUS Node 1Node 2

34. Why do I care? VM memory should come from the “local NUMA node” Computer CPU BUS Memory VM Back Channel Memory BUS Node 1Node 2

35. How does this work today? Hyper-V tries to get all memory for a virtual machine from a single NUMA node When it cannot – the virtual machine “spans” NUMA nodes Users can set preferred NUMA nodes for virtual machines in order to get the best distribution

36. Disabling NUMA Spanning Makes the system behave like multiple small computers Computer CP U BUS Memory VM Back Channel Memory BUS Node 1Node 2

37. 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

38. 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

39. ARP Spoofing Prevention (NEW in Windows Server 2008 R2 SP1) Relevant To Multi-Tenant Environments Mutually Untrusted VM’s (Such As A Hoster With VM’s From Different Customers) NEW In Windows Server 2008 R2 SP1 (post-beta) Hyper-V Virtual Switch Exposes API To Associate MAC Address With IP Address Prevents VM From Sending Out An ARP Response If MAC/IP’s Don’t Match Supports One or Many IP Addresses Per Virtual Network Adapter Supports IPv4 and IPv6

40. 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

41. DM & Exchange Server Most roles are candidates for virtualisation HUB CAS Edge Mailbox No support for Dynamic Memory

42. SCVMM 2008 R2 SP1

43. 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

44. Dynamic Memory: Configuration Settings

45. 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

46. Performance And Resource Optimization (PRO)

47. Updated VMM PRO Packs VMM PRO management packs for “VM Right Sizing” Located in AMD64\VirtualizationMP

48. 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 TechCenterSystem Center TechCenter

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