1. Virtualization 2. Scalable 3. Shared 4. Metered Usage
Layers of Cloud Computing
- Infrastructure as a service – IaaS
- Hosts the virtual machine (VM)
- Hosts the storage (block)
- Hosts the networking hardware
- Users are in total control
- Platform as a service – PaaS
- Hosts software frameworks
- Hosts database
- Software as service -SaaS
- The application is provided to the client through a thin client interface.
- Hosts web-services
- Hosts applications
- Hosts multimedia
Virtualization is the main factor of Cloud computing. Virtualization allows simultaneously executions of more than one Operating Systems on the same machine. Two main types of virtualization are hardware virtualization and software virtualization. It can be implemented by different ways:
Virtual machine (VM) has own operating system (guest OS), applications and virtual resources. A program running under a virtual environment should exhibit identical behavior.
Virtual Machine Monitor (VMM):
A virtual machine runs by VMM (Hyperviosr). VMM is an other software layer between physical machine and virtual machine.The VMM should be in full control on the virtualized resources. VMM manages the virtual machines (Guest OS & its application)
1. Full Virtualization
- Unmodified guest operating system
- Simulates hardware within software
- It is a heavy process
- Method 1: Trap and emulate
- Method 2: Binary translation
1.1 Native Hypervisor (bare-metal) - Type1
- Directly interrupts with hardware
- Example: Xen, Hyper-V
1.2 Hosted Hypervisor - Type2
- Low performance due to binary translation
- Software assisted
- Example: VMWare, VirtualBox etc…
2. Para Virtualization:
- Guest OS should be modified i.e XEN
- Not run time translate
3. Hardware Virtualization:
- VMM in 1st ring.
4. OS Virtualization:
- Shared OS
- HW->OS->Container Engine->Container
Virtual Machine Migration:
- For network latency
- For power reduction
- For server consolidation
- For maintenance
- For load balancing
- For availability
- Storage based application
- SLA validation
- Consumed power
- Consumed resources
- containerzed os based , process base
- Push phase: The source VM continues running while certain pages are pushed across the network to the new destination. To ensure consistency, pages modified during this process must be re-sent.
- Stop-and-copy phase: The source VM is stopped, pages are copied across to the destination VM, then the new VM is started.
- Pull phase:The new VM executes and, if it accesses a page that has not yet been copied, this page is faulted in (“pulled”) across the network from the source VM.
- Pre-Copying or Post Copying
Cloud Deployment Models
- This is available for public use alternatively for a large industry group.
- A hybrid cloud combines multiple clouds where those clouds retain their unique identities, but are bound together as a unit.
- A hybrid cloud may offer standardized or proprietary access to data and applications, as well as application portability.