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Planning and Designing Server Virtualisation

ICANWK525B Configure an Enterprise Virtual Computing Environment ICTSUS5187A Implement Server Virtualisation for a Sustainable ICT system. Planning and Designing Server Virtualisation. Planning to Virtualise Servers. An organisation has existing servers

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Planning and Designing Server Virtualisation

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  1. ICANWK525B Configure an Enterprise Virtual Computing EnvironmentICTSUS5187A Implement Server Virtualisationfor a Sustainable ICT system Planning and Designing Server Virtualisation

  2. Planning to Virtualise Servers • An organisation has existing servers • Issues: lots of power, low utilisation of resources, cost of maintenance • They are considering the feasibility of virtualising these servers • They have asked you to assess this feasibility • You need to write them a feasibility report

  3. Things to Remember • Virtual servers need the same disk space as real ones • Virtual servers need roughly the same RAM (memory) as real ones • Virtual servers need the same bandwidth as real ones • Virtual servers, on average, only utilise about 15% to 20% of their CPU capacity

  4. Plan for Replacement Hardware • You will either use the existing hardware, buy completely new hardware, or have a mix of old and new hardware • Given the 15-20% rule, plan for about 1/5 the number of equivalent CPUs • Less physical servers • However, same RAM requirements, so more RAM per physical server than before • Same disk requirements • Either more disks in each server, or a SAN • Same bandwidth, less servers => more or faster NICs per server. Even more so, if using SANs

  5. Plan for Redundancy & Flexibility • Ensure you can migrate VMs between physical servers, to allow you to have physical server downtime • Ensure flexibility to map drive space to all the VMs across all the physical servers • Ensure some spare capacity in case one physical server dies • Implication: some spare server CPU/RAM capacity • Implication: a SAN for the physical drives • Implication: more bandwidth and physical infrastructure for the SAN

  6. Take a Baseline • Baseline: measurement of the current system • I would measure over a week: • Peak/average/minimum CPU usage per day • Peak/average/minimum RAM usage per day • Peak/average/minimum network bandwidth per day • Peak/average/minimum disk bandwidth per day • This will inform you as to the hardware and networking capabilities of the new system

  7. Example Scenario • Ten existing servers, each with two quad-core Xeon CPUs, 8GB RAM, 2TB disk space • Connected to a switch with 10Gbps Ethernet ports • Baseline measurements: • 15% CPU utilisation, peaks at 100% on some servers for a few minutes • Average RAM use: 6GB per server, peaks at 8GB but not at same time across all servers • Network usage: two servers average 6 Gbps, the rest average 1 Gbps, with occasional peaks of 5Gbps • Disk usage: at present, 14TB of the 20TB used • Disk bandwidth: average 3Gbps total, peaks to 5 Gbps

  8. Example Scenario • Scale CPUs to 1/5: have only four quad-core Xeon processors • RAM: still need 10x6GB = 60GB, perhaps a bit more • Network: need at least 20Gbps • Disk usage: need at least 14TB • Disk bandwidth: need at least 5Gbps • Now, we have to spread this across the new physical servers • We want redundancy and flexibility

  9. New Scenario • 2 or 3 servers: I would go for 3 servers • 2 can carry the load while one is down • Two quad-core Xeons per server => 6 Xeons not 4 • RAM: 24GB per server times 3 = 72GB total • Bandwidth to the users: we need a 10Gbps multiport switch plus 7Gbps per server to the switch => go for 10Gbps NICs per server • Gives 30Gbps overall bandwidth

  10. New Scenario • Storage Area Network (SAN): • RAID 6, we need 2 drives spare in an 8-drive array • Eight 3TB drives = 24TB, but only six 3TB = 18TB usable • Bandwidth to the SAN: 2Gbps per server, so go for 10Gbps NICs • 3 NICs at 10Gbps is overkill • SAN device needs a 10Gbps NIC, plus a 10Gbps multiport switch to the servers

  11. New Scenario

  12. Scenario Results & Questions • 10 servers, now 3: power savings • Redundancy with 3 servers: migrate VMs if/when one server is down • Need SAN device & associated switch/cables • May need new client-side switch • Can we re-use some of the existing servers? • Hard to tell without knowing the exact servers

  13. Feasibility Report • Feasibility report: is it feasible to virtualise the servers. Sections of the report: • Overview of the problem • Analysis of existing hardware • Baseline of existing system • Recommendation of new design • Advantages, disadvantages of new design • Ability to re-use existing infrastructure • Risk analysis: • What could go wrong with the new design • What could go wrong during the transition • Will be a multi-page document, very formal

  14. Feasibility Report • Feasibility given constraints: budget, time to complete, existing space etc. • You will need to give multiple options for new systems, plus the “null” option: do nothing • You can still mark one as the preferred option • Compare the advantages & disadvantages of each: cost, performance, risks. • Gives customer the ability to choose something that meets their organisational requirements and meets their constraints

  15. Designing the Solution • The organisation has chosen one of the solution plans • Now it is design time • Choose specific hardware to match the plan • Choose specific virtualisation software • Ensure existing customer server software can be virtualised and migrated into VMs on the new system

  16. The Main Server Virtualisation Products • VMware vSphere with ESXi • Microsoft Hyper-V running Win Server 2012 • Links: • VMware: Comarison Against Hyper-V • InfoWorld: vSphere versus Hyper-V • Pay per Cloud: vSphere versus Hyper-V • Not just technical comparison, think of training, support, ease of management, ability to work with existing infrastructure • i.e the total cost of ownership (TCO)

  17. Migrating Existing Servers to VMs • Need to be able to migrate software on existing servers into VMs: • Operating system, applications, data stores • Both VMware and Hyper-V come with tools to do this: • VMware vCenter Converter • Microsoft System Center Virtual Machine Manager

  18. Software & Hardware Requirements • During your baseline, you should have done an audit of existing server operating systems and the application they are running • e.g. Windows Server 2008, Linux, web services etc. • Make sure any solution you choose can virtualise these systems. • Both vSphere and Hyper-V can do Windows and Linux • vSphere has minimum hardware requirements • If chosen, make sure your design meets these

  19. Environmental Considerations • Physical space, power, cooling • If replacing an existing server system, you will most likely need less space, power, cooling • However, during the transition, you may need more space, power, cooling • And the transition may take weeks • For both a new and a replacement build, you must determine the space, power and cooling requirement of the servers

  20. Environmental Considerations • Server room design is out of scope for this unit. Some useful links: • M.Moser: Server Room Design • UC Davis: Server Room Best Practices • Requirements for the Design of ICT Rooms

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