With OpenStack's architecture, is it possible to, for instance, have a PowerPC64 (Altivec) machine, a Intel CoreDuo machine, and a ARMv6 all on the same cluster?
Or is this impossible, because of the restrictions in building buildpacks when deploying to multiple architectures?
EDIT: Whoops, I meant OpenStack, not OpenShift ;)
The answer above is correct (answer from developercorey).
Although whether this suits you depends on how its managed and what your trying to achieve. Typically when you add servers with different physical attributes such as CPU, Disk, Network cards etc you group them into different host aggregates.
By default when you launch a VM it will try and find a suitable host, but you can also tag it, so for example if your VM required alot of disk IO, you might want to place it on a host that has SSD drivers. So you can put those hosts into a 'SSD' aggregate, and then when launching your VM you can make sure it goes to a host in that aggregate.
If your just trying to make the most out of the hardware you have, then I don't see any issue by mixing them.
I don't think that they have to be, but I do believe that they only build packages for 1 or 2 architechtures, so I'm not sure how many options you really have there.
Related
i am really confuse about the main difference between Open Stack and development Stack ?
is it different version or different platform ?
First of all, let's get the terminology correct. You are talking about OpenStack (one word) and DevStack (one word).
OpenStack is a suite of services for managing computing and related resources. You typically use it for managing "cloud computing" resources, consisting of multiple physical compute and storage servers. Setting up a system like this for production use on "real" hardware takes a lot of time and expertise.
DevStack is a essentially a set of scripts that will set up set up a simple OpenStack test environment running as virtual machines on (typically) a Linux PC with a few GB of RAM and a chunk of free disk space. The purpose is to allow a developer to set up a tiny cloud for trying things out, and doing service development work.
OpenStack and DevStack are neither different versions or different platforms. They are different parts of a larger whole. (You could say that DevStack is part of the OpenStack suite of software. Development of OpenStack and DevStack are handled by the same umbrella organization under the same governance, etc, etc.)
I am beginning to study the use of virtual machines with realtime applications, specifically network applications.
While I do understand the limitations and concerns, I'd like to get ideas as to how to get started on this task.
I am going to use a DPDK sample application over Linux, and probably use VMWare for starters. However, I do not know what my first steps with respect to setting up VMWare should be.
First I think it is better to use open source solution like QUEM/KVM for your virtualization platform. Many platform exist for run high performance network functions on virtualized platforms you can see OpenNetVM for example in order to get basic ideas.
On Windows, I've used NEWT in the past, but it's difficult to use, not current (but I can find old copies on non-MS sites), and difficult though possible to degrade just the app's view of the network without messing up everything else on the machine like the VPN connection and NAS volumes.
On Mac, the Network Link Conditioner that is available with Xcode is far too limited and in particular doesn't model bursts, which is my current immediate interest.
I'm also interested in Windows programs running in a VMware VM, and that's already going through an emulated network connector. I wonder if that can be made to do the traffic shaping?
In summary, can someone suggest a tool that I ought to be using for this?
I guess http://henrydu.com/blog/how-to/simulate-a-slow-link-by-linux-bridge-123.html should work on your mac. It uses traffic control with ifconfig, something you might want to google for.
I am a newbie with Xen.I want to know how does Xen work.
It's really a puzzle when facing the code and I don't know where to start.
Are there some easy articles for me?
Since you mention looking at the code, I assume you want to understand the technical details of Xen and not just merely how to start a VM.
As with all problems, start with something simple and then work your way up. Some pointers:
Be sure to have the prerequisite experience under your belt. In particular, strong C and Linux affinity, but also x86 paging and virtualized memory workings.
Make sure you have a sound grasp of the general Xen architecture. For instance, paravirtualized versus hardware-supported virtualization, the special role of the management domain (Dom0) compared to unprivileged domains (DomU), etc.
Investigate the the Xen components running in Dom0:
The Xen control library (libxc) which implements much of the logic relating to hypercalls and adds sugar around these (look in tools/libxc).
The swiss army knife for administrating Xen, namely the Xen light library (libxl). This library replaces the deprecated xm tool with the xl tool and takes care of all your maintenance tasks such as starting/stopping a VM, listing all running VMs, etc. For all these operations, it works in tandem with the aforementioned libxc. (Libxl lives in tools/libxl.)
The Xenstore is a tree-like data structure from which all running domains can retrieve and store data. This is necessary since all I/O goes through Dom0 (not the hypervisor!), and domains need to communicate with Dom0 how they are going to pass I/O along. (Look in tools/xenstore.) You can inspect the Xenstore with a tool such as xenstore-ls.
the blkback/netback kernel drivers which pass the data over shared channels to the VMs. (You will find these drivers in a recent Linux kernel (e.g. >= v3.0) that has so-called PVOPS support).
Take a look at the console daemon (tools/console). Note that sometimes the Qemu console is actually used. Qemu also comes in the pictures as a default backend for if you choose a file-backed virtual storage for a VM.
Experiment with the 'Xen-way' of inter-VM communication: Grant tables, event channels and the Xenstore. With these fundamentals you can create your own shared channel between VMs. You can do this, for example, with writing a kernel module that you use in two domains to let them talk to each other.
I can also give some pointers in the source that you can check out:
xen/xen/include/public/xen.h will give you a list of all the hypercalls with comments what they do.
xen/xen/include/xen/mm.h gives you an introduction to the different memory terminology used by Xen (i.e., real versus virtualized addresses and page numbers). If you don't grasp these differences, then reading the hypervisor code will surely be frustrating.
xen/xen/include/asm-x86/config.h gives an overview of the memory layout of Xen.
xen/tools/libxc/xenctrl.h exports a large list of interesting domain control operations, which gives an abstract view of task division between Dom0 and the hypervisor.
Last but not least, the book 'The Definitive Guide to the Xen Hypervisor' by David Chisnall comes highly recommended. It covers all these topics and more in a thorough, technical fashion with plenty of code examples.
The Xen wiki and developer mailing lists are also a great resource for understanding Xen.
If you have a more specific question, then I can give you a more specific answer.
Here are few links which will guide you with ZEN Start up.Hope they will be useful.
http://www.howtoforge.com/howtos/virtualization/xen
http://wiki.xen.org/wiki/Category:HowTo
http://wiki.debian.org/Xen
For me, that is the best and more concrete tutorial with examples and step by step to start. I used it when I started.
Then you can read a lot more on Xen documentation itself or some books but as a starting point that allows you to easily install and test Xen, I choose that tutorial from Debian Wiki.
If you just want an overview, you may read this: http://wiki.xenproject.org/wiki/Xen_Project_Beginners_Guide.
This will introduce you to Xen hypervisor, suggest configuration to set up virtual machines, provide information about the networking and finally have details about tools for the management of virtual machines.
This documentation is to get the Xen specifically on ubuntu (Most importantly, it works!)
https://help.ubuntu.com/community/Xen
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However, if you want to go to the next level and understand the working of Xen; Xen architecture, memory management, device management, CPU scheduling etc., I would recommend reading the book "The Definitive Guide to the Xen Hypervisor".
I am developing a distributed file system using Java, I cannot give many details at this moment. I need to test some things on Linux, I will use WMWare server an install Linux inside a virtual machine. Is there any difference between the simulated network card and a real ethernet interface?
I am developing a distributed file system ... I will use WMWare server an install Linux inside a virtual machine.
VMware is great for this sort of thing. There should be no difference except, as RichieHindle said, in performance, especially if you're planning to run multiple vms on the same server.
Use real hardware if you want usable performance benchmark results.
Java is it's own 'VM'... on top of a layer of virtualization in the guest OS... on top of VMware... on a virtual execution model CPU. Take a little virtualization here, add a little virtualization there, and pretty soon we're talking about some real abstraction!
From the point of view of application code, no, there's no difference.
The only visible difference might be in performance - the speed of response and exact timings of things might be different, but you're talking microseconds.
There's so much general-purpose software that works flawlessly under VMs that the answer to almost every question of the form "Are VMs different from real machines?" at the application level is "No".
(Things might be different if you were talking about kernel-level driver software.)