Flashcards
Module 25
Cards in this deck (11)
- 1EXPLAIN VIRTUALIZATION?VIRTUALIZATION:
- is for efficient resource utilization
- involve software abstraction so it behaves like hardware
- common method of virtualization is virtual machines(acts like hardware)
- virtual machines have redefined elements of IT(such as the ease of configuring new machines)
OVERVIEW OF VIRTUAL MACHINES & MEMORY:
- virtual machines are multiple installations of an operating system on a single physical computer(not simulated but real installations of an operating system)
- each VM is isolated from the other, enable by protocols & APIs(application programming interfaces/hypervisor). offers greater flexibility, reduced costs & increased value
- memory requirements(as running multiple operating systems so large memory required)
KEY BENEFITS:
- increased flexibility(can create new VM's & clone them quickly & easily), reduces cost, very scalable, performance and reliability is as good as the hardware that underpins it - 2EXPLAIN THE PURPOSE OF VIRTUAL MACHINES & USES?PURPOSE OF VIRTUAL MACHINES(VMs):
- used to perform tasks like a separate computer
- guest VM's are created within the physical host computer(a chunk of hardware running these virtual machines)
- a single host can service multiple guest VM's
- limited only by the physical resources available on the physical host itself and how much has been allocated to each virtual machine
COMMON USES OF VIRTUAL MACHINES:
- trying new operating systems
- testing new software
- disaster recovery
- system backup(can capture the state of the system so if changes are wrong, you can revert back)
- business continuity(easy to make multiple copies of exact same system in a cluster/availability group, so if the primary one goes down, you can just flip over to another system)
- may be used for legacy systems
- offer physical to virtual conversion(where you may have a physical computer running a certain application/service that you would like to virtualize. this captures the state of a physical system and packages it up into a virtual machine - 3EXPLAIN HOW TO CONFIGURE A VIRTUAL MACHINE?COMMON CONFIGURABLE SETTINGS FOR A VIRTUAL MACHINE:
- windows based-server running Hyper-V(hypervisor - built into windows)
- once you have Hyper-V manager enabled you can start creating virtual machines
- certain settings are not configurable while the system is running
- notable settings are memory(physical host system must have enough memory to support these virtual machines), the processor(can increase so machine believes it has more processes), the hard drive configuration(if configured as a SCSI controller, the virtual machine will submit requests to the storage subsystem using the SCSI protocol), & the network adapter(the virtual switch connects VM's)
- to change these settings go to hyper-v manager, virtual machines, right-click a VM, click settings
- to find the configuration of the host system go to task manager & then the performance tab
- VM settings have a DVD drive option which is an ISO file just to represent a DVD drive. So if providing an iso file, which is an image of a DVD, the operating system will read that file as if it was a DVD, so believes there is a DVD tray - 4EXPLAIN RESOURCE REQUIREMENTS FOR VMs?REQUIREMENTS FOR VIRTUAL MACHINES:
- physical system known as the host, represents the actual hardware, the computer
- hypervisor is the software necessary to support virtualization(a layer that allows each individual virtual machine to access the physical hardware without interfering with each other)
- individual virtual machines(represented by 3 stacks for a single 1(applications, running on a guest operating system, running on virtual hardware)
- determine what the resource requirements for each virtual machine are going to be & can't forget about the physical host system itself that's still active(needs resources as well)
DETERMINING VIRTUAL MACHINE RESOURCE REQUIREMENTS:
- study the vendor published requirements(know what an actual computer may need if it were to be implemented as a physical system)
- ensure the appropriate amount of memory for applications
- maybe able to provide excess memory resources(may improve VM performance. in certain cases, the operating system won't recognize excess memory, resulting in ineffective use of resources
- know the operating system limits - 5GIVE EXAMPLES OF WINDOWS SERVER OS MEMORY REQUIREMENTS & CONSIDERATIONS FOR USING THE PERFORMANCE MONITOR?WINDOWS SERVER OS MEMORY REQUIREMENTS:
- Windows Server 2008 R2 Datacentre(operating system), 2 TB(maximum memory)
- Windows Server 2008 R2 Enterprise, 2 TB
- Windows HPC Server 2008 R2, 128 GB
- Windows Web Server 2008 R2, 32 GB
- Windows Server 2003 R2 SP1 Datacentre X64, 1 TB
- Windows Server 2003 R2 SP1 Enterprise X64, 1 TB
CONSIDERATIONS FOR USING THE PERFORMANCE MONITOR:
- performance monitor is a Windows utility that you can use inside a VM to gather up information about resource consumption
- works well for memory usage
- not ideal for tracking CPU and I/O usage(no means to dedicate a certain amount of processing with respect to cycles and percentages to a virtual machine)
- can help with VM capacity planning
- when running it with a virtual machine it does not capture resources available to the whole(host) system, hence measurements can be skewed - 6EXPLAIN EMULATORS?EMULATORS:
- guest systems do not have direct access to the actual hardware of the host system, so guest systems(VM's) use virtual devices for the configuration
- emulators are used to present what appears to be an actual device to the guest system
- emulators translate requests from the guest system to the host system(so the host can actually access its real hardware)
COMMON EMULATED DEVICES:
- will find several emulated devices when it comes to configuring a virtual machine
- common emulated devices configured for the virtual machines include legacy network adapters, floppy disc drives, IDE/SCSI hard drives, CD/DVD drives
- emulators allow the virtual machines to access those files in the exact same manner as they would access an actual real drive - 7EXPLAIN EMULATOR REQUIREMENTS?EMULATOR REQUIREMENTS:
- dependent on the host system(host operating system and/or version, hypervisor)
- emulators exist because virtual machines are generally unaware they are running as virtual machines, but newer host computers are aware of the virtual machines they are hosting(so newer operating systems & hypervisors require fewer emulators(Microsoft Hyper-V(generation 1 Vs generation 2, generation 2 supports VMBus protocol which reduces the use of emulators as it allows multiple devices to be accessed without an emulator so perform better) - 8EXPLAIN VM SECURITY REQUIREMENTS?VIRTUALISATION SECURITY:
- data on either the physical host or VM can potentially be accessed by over machines
- need to implement measures to ensure the physical systems or secure as well as each individual virtual machine. need monitor & manage that everything is kept current and up to date
VIRTUALIZATION SECURITY MEASURES:
- granular security controls, security procedures, control & authority(need to be specific)
- protecting against vulnerabilities of the physical system
- setting security policies(through software & peoples actions on a daily basis) - 9EXPLAIN THE NETWORK REQUIREMENTS ASPECT OF VIRTUALISATION & NETWORK CHALLENGES WITH VDI ?NETWORK REQUIREMENTS:
- physical computers hosting multiple virtual machines can have much higher network demands(consider bandwidth optimization, installing multiple network adapters on the physical host, compression or encryption offloading & traffic prioritization techniques
NETWORK CHALLENGES WITH VDI(VIRTUAL DESKTOP INFRASTRUCTURE):
- VDI can be implemented
- VDI is taxing to network(have client systems all trying to access that single physical computer to see a desktop & run an application, is fairly intensive graphically)
- consider types of networks(how users are connecting can affect performance - LAN, WAN, internet
- Delayed performance/lag(particularly for real-time applications)
- ultimately test & verify your network performance throughly before deploying a VDI configuration in hopes that your network can support it - 10EXPLAIN HYPERVISORS?HYPERVISORS:
- central to the concept of virtualization(can not have without a hypervisor)
- its job is to separate the operating system & applications from physical hardware
- it enables a physical host machine to operate numerous guest machines
- capabilities extend to personal computers as well as servers(there are also desktop level hypervisors)
KEY BENEFITS:
- creates logical separation for virtual machines
- virtual machines can be completely isolated from each other(if one fails, others are not affected)
- makes it easier to move & migrate being separated & isolated, so you get portability - 11EXPLAIN THE TYPES OF HYPERVISORS & SECURITY CONCERNS?TYPES OF HYPERVISORS:
- type 1 hypervisor & type 2(difference is the presence of a host operating system on the actual physical hardware)
- in type 1 the hypervisor can be installed directly onto the hardware, becoming the operating system. from there you can start creating virtual machines right away(will perform better as no overhead)
- in type 2 you start with your basic hardware but have to install an operating system on that hardware before you get your hypervisor(more functionality)
SECURITY CONCERNS:
- something has to be installed on the physical hardware, so soon as you start to install any kind of software, malware & rootkits do become possible.
- if physical host system becomes compromised with some kind of malware, not only can this damage the physical host system but it might also be able to access all of the virtual machines running on that system. hence type 2 is better in this respect as its easier to configure its anti-malware software when you've already got an operating system
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- Learning Technology Specialist CompTIA A+ (Core 1) Flashcards on Module 25, created by Chantelle Knight on 18/09/2021.
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- Chantelle Knight
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