Virtualization Techniques & Cloud Compting
by Ahmed Mekkawy on May 15, 2010
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Virtualization Techniques & Cloud Compting — Presentation Transcript
- Virtualization Techniques & Cloud Computing Ahmed Mekkawy [email_address] This presentation is under creative commons BY-NC-SA license
- What will talk about
- Virtualization
- What is it?
- Why do we use it?
- Is it really a new technology?
- Virtualization Types
- Cloud Computing
- What is it?
- Why to use it?
- Is it mature and dependable? Should we use it?
- Example: Amazon Web Services
- Virtualization
- What is Virtualization?
- Is it a new technology?
- No, IBM started it in the 70's (or even 60's).
- Is chrooting considered virtualization?
- Not really, though it does the trick in some situations.
- Why Virtualization?
- Cost Reduction.
- Isolation and creating protected environment.
- Testing and evaluation of OS, kernel, or an application.
- Teaching.
- Ease of duplication.
- Relocation (and disaster recovery).
- Running Application not supported by the host.
- Green IT.
- … etc.
- Virtualization Techniques
- Full Virtualization.
- OS-level Virtualization.
- Partial Virtualization (Historical, not used).
- Paravirtualization.
- Hardware-assisted Virtualization.
- Full Virtualization
- Concept: The host OS emulated a hardware layer for each guest OS.
- Pros: Stability, comptability, guest OS is not patched.
- Cons: resources, porfromance.
- OS-Level Virtualization
- Concept: Same OS for everyone (host & guest), and isolation is only in the userland. If you run `ps aux` in the host, you will see all guests processes.
- Pros: low overhead, highest performance.
- Cons: isolation, stability.
- Examples: FreeBSD Jails, Solaris Containers, Virtuzzo/OpenVZ.
- Paravirtualization
- Concept: A thin layer (called the hypervisor, you can think of it as a kernel more than an OS), interfaces the hardware to all OS's (host and guest), Dom0 is called ”the privilged domain” which can issue commands to the hypervisor.
- If Dom0 crashed (not the hypervisor), the guest OS still runs fine, anyway you won't be able to control the hypervisor till you reboot.
- The hypervisor provides API's to the DomU's kernels, which are not actually real kernels, they only interface these API's to the userland, not real kernels.
- Paravirtualization Cont'd
- Pros:
- Stability is very close to the hardware virtualization.
- Performance is very good (nothing can beat OS-level virtualizatin in this matter).
- Overhead is very low (kernel level only, and not even a complete kernel).
- Cons:
- Not easy to implement (it's getting better these days).
- Both host and guest kernels has to be patched.
- Maintainability.
- Example: Xen
- Pros:
- Stability is very close to the hardware virtualization.
- Performance is very good (nothing can beat OS-level virtualizatin in this matter).
- Overhead is very low (kernel level only, and not even a complete kernel).
- Cons:
- Not easy to implement (it's getting better these days).
- Both host and guest kernels has to be patched.
- Maintainability.
- Hardware-assisted Virtualization
- Sometimes it's called accelerated virtualization or HVM (Hardware Virtual Machines).
- Concept: Hardware provides support to run instructions independently for each OS.
- Implementation: IBM 370 (1972), Intel VT, AMD-V, UltraSparc, and others.
- Examples: linux KVM, Vmware fusion, M$ VirtualPC, Xen, Virtual Box.
- Hardware-assisted Cont'd
- Pros:
- Highly reduces (theoritically eleminates) the need to patch the guest OS.
- Theoritically optimal performance.
- Great Stability.
- Cons:
- Hardware restrictions.
- A “pure” hardware-assisted virtualization approach, using entirely unmodified guest operating systems, involves many VM traps, and thus high CPU overheads; this limits scalability and the efficiency of server consolidation. This performance hit can be mitigated by the use of paravirtualized drivers; the combination has been called “hybrid virtualization”.
- Cloud Computing
- So What is Cloud Computing Anyway? Do you find yourself saying "am I the only one that is confused about this?"
- Two openions about this:
- My Openion? Well those 2 openions are the same.. It's a marketing hype that will drive the techies to make new technologies that didn't exist before, like what always happens...
- Cloud Computing Cont'd
- Are all clouds are public ones like AWS?
- Of course not, there are private clouds, check eucalyptus (or ubuntu enterprise cloud), it's an open source (and free software, as speech & as beer) software.
- It's also a business hype, everybody is talking about it.
- The most known public clouds are Amazon and Rackspace clouds.
- Everything is great, it's cheaper, more performant, and sustainable... where's the trick?
- Concerns about Clouds
- Who said that performance is better? CPU wise?
- Stability? Talk to me about it.
- Security and privacy... duh!
- RMS harsh words about it.. why is all that buzz?
- Cloud Pros
- Very fast provisioning.
- Easy scaling up/down.
- Virtually unlimited resources.
- Agility.
- Cost, on certain situations anyway.
- Metering, you pay as you go.
- Bottom Line
- Cloud is good when you have large scale, variable load application, and you need to minimize the cost.
- Cloud is also good in application that are memory intensive but not CPU intensive, e.g RoR applications.
- It should be suitable soon, this technology have the potential but it just needs to get more mature.
- If you are a system developer, it's a very good chance to enter this hype now, cause later it will be very complicated (if it's not already late).
- AWS Overview
- Now let's talk about AWS stack, we chose it cause it's one of the most complicated clouds around.
- AWS is based on Xen Virtualization.
- It contains the following services:
- Elactic Computer Cloud (EC2): computing.
- SimpleDB, Relational DB Services (RDS): Database.
- Simple Queue Service (SQS), Simple Notifications Service (SNS): Messaging.
- Simple Storage Service (S3): Storage.
- Elastic Block Storage (EBS): Storage.
- Others: like CloudFront, CloudWatch, AutoScaling, … etc.
- The minimal stable is EC2 + EBS
- EC2
- Computing instance, the harddisk is totally volatile if the instance crashed (which happens, rarely but happens).
- The smallest instance type is 1.7G RAM, 1 CPU (1~1.2GHz), 32bit OS. The largest is 68.4 G RAM, 8 CPU (3.25~3.9GHz), 64bit OS.
- Very Obvious that CPU is the most costy part
- 2 identical instance with only difference in CPU (1 CPU of 1~1.2GHz Vs. 2CPUs of 2.5~3GHz), both are 1.7G RAM, 32 bit OS. The price difference is exactly double.
- EBS & S3
- They share that they are redaundant, reliable storage. The maximum that happened before is a blackout, but never a dataloss.
- EBS can be mounted to a single EC2, which is bad limitation.
- S3 is to be accessed via http protocol, can be a great help in serving static http files from outside your servers.
- Thank You [email_address]
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