1. Planning and Designing Server Virtualisation

4.  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

5.  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

6.  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

7.  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

8.  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

9.  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

10.  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

11.  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

12.  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

14.  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

15.  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

16.  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

17.  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

18.  VMware vSphere with ESXi  Microsoft Hyper-V running Win Server 2012  Links: ◦ VMware: Comarison Against Hyper-V VMware: Comarison Against Hyper-V ◦ InfoWorld: vSphere versus Hyper-V InfoWorld: vSphere versus Hyper-V ◦ Pay per Cloud: 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)

19.  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 VMware vCenter Converter  Microsoft System Center Virtual Machine Manager Microsoft System Center Virtual Machine Manager

20.  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 requirementshardware requirements  If chosen, make sure your design meets these

21.  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

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