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  • How Visual WebGui helps ASP.NET Cloud-based apps

    - by Visual WebGui
    Everyone is talking about Cloud computing and moving to the cloud (public or private), but very few have actually done it so far. The reason is that the process of migrating existing applications to the cloud is a lot more complicated than one might think which is exactly where the Visual WebGui technology comes in for a rescue. In the past year the Visual WebGui R&D Team have been intensively working on a tool-based solution that gives Microsoft application developers and enterprises a simpler...(read more)

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  • Developing a Cost Model for Cloud Applications

    - by BuckWoody
    Note - please pay attention to the date of this post. As much as I attempt to make the information below accurate, the nature of distributed computing means that components, units and pricing will change over time. The definitive costs for Microsoft Windows Azure and SQL Azure are located here, and are more accurate than anything you will see in this post: http://www.microsoft.com/windowsazure/offers/  When writing software that is run on a Platform-as-a-Service (PaaS) offering like Windows Azure / SQL Azure, one of the questions you must answer is how much the system will cost. I will not discuss the comparisons between on-premise costs (which are nigh impossible to calculate accurately) versus cloud costs, but instead focus on creating a general model for estimating costs for a given application. You should be aware that there are (at this writing) two billing mechanisms for Windows and SQL Azure: “Pay-as-you-go” or consumption, and “Subscription” or commitment. Conceptually, you can consider the former a pay-as-you-go cell phone plan, where you pay by the unit used (at a slightly higher rate) and the latter as a standard cell phone plan where you commit to a contract and thus pay lower rates. In this post I’ll stick with the pay-as-you-go mechanism for simplicity, which should be the maximum cost you would pay. From there you may be able to get a lower cost if you use the other mechanism. In any case, the model you create should hold. Developing a good cost model is essential. As a developer or architect, you’ll most certainly be asked how much something will cost, and you need to have a reliable way to estimate that. Businesses and Organizations have been used to paying for servers, software licenses, and other infrastructure as an up-front cost, and power, people to the systems and so on as an ongoing (and sometimes not factored) cost. When presented with a new paradigm like distributed computing, they may not understand the true cost/value proposition, and that’s where the architect and developer can guide the conversation to make a choice based on features of the application versus the true costs. The two big buckets of use-types for these applications are customer-based and steady-state. In the customer-based use type, each successful use of the program results in a sale or income for your organization. Perhaps you’ve written an application that provides the spot-price of foo, and your customer pays for the use of that application. In that case, once you’ve estimated your cost for a successful traversal of the application, you can build that into the price you charge the user. It’s a standard restaurant model, where the price of the meal is determined by the cost of making it, plus any profit you can make. In the second use-type, the application will be used by a more-or-less constant number of processes or users and no direct revenue is attached to the system. A typical example is a customer-tracking system used by the employees within your company. In this case, the cost model is often created “in reverse” - meaning that you pilot the application, monitor the use (and costs) and that cost is held steady. This is where the comparison with an on-premise system becomes necessary, even though it is more difficult to estimate those on-premise true costs. For instance, do you know exactly how much cost the air conditioning is because you have a team of system administrators? This may sound trivial, but that, along with the insurance for the building, the wiring, and every other part of the system is in fact a cost to the business. There are three primary methods that I’ve been successful with in estimating the cost. None are perfect, all are demand-driven. The general process is to lay out a matrix of: components units cost per unit and then multiply that times the usage of the system, based on which components you use in the program. That sounds a bit simplistic, but using those metrics in a calculation becomes more detailed. In all of the methods that follow, you need to know your application. The components for a PaaS include computing instances, storage, transactions, bandwidth and in the case of SQL Azure, database size. In most cases, architects start with the first model and progress through the other methods to gain accuracy. Simple Estimation The simplest way to calculate costs is to architect the application (even UML or on-paper, no coding involved) and then estimate which of the components you’ll use, and how much of each will be used. Microsoft provides two tools to do this - one is a simple slider-application located here: http://www.microsoft.com/windowsazure/pricing-calculator/  The other is a tool you download to create an “Return on Investment” (ROI) spreadsheet, which has the advantage of leading you through various questions to estimate what you plan to use, located here: https://roianalyst.alinean.com/msft/AutoLogin.do?d=176318219048082115  You can also just create a spreadsheet yourself with a structure like this: Program Element Azure Component Unit of Measure Cost Per Unit Estimated Use of Component Total Cost Per Component Cumulative Cost               Of course, the consideration with this model is that it is difficult to predict a system that is not running or hasn’t even been developed. Which brings us to the next model type. Measure and Project A more accurate model is to actually write the code for the application, using the Software Development Kit (SDK) which can run entirely disconnected from Azure. The code should be instrumented to estimate the use of the application components, logging to a local file on the development system. A series of unit and integration tests should be run, which will create load on the test system. You can use standard development concepts to track this usage, and even use Windows Performance Monitor counters. The best place to start with this method is to use the Windows Azure Diagnostics subsystem in your code, which you can read more about here: http://blogs.msdn.com/b/sumitm/archive/2009/11/18/introducing-windows-azure-diagnostics.aspx This set of API’s greatly simplifies tracking the application, and in fact you can use this information for more than just a cost model. After you have the tracking logs, you can plug the numbers into ay of the tools above, which should give a representative cost or in some cases a unit cost. The consideration with this model is that the SDK fabric is not a one-to-one comparison with performance on the actual Windows Azure fabric. Those differences are usually smaller, but they do need to be considered. Also, you may not be able to accurately predict the load on the system, which might lead to an architectural change, which changes the model. This leads us to the next, most accurate method for a cost model. Sample and Estimate Using standard statistical and other predictive math, once the application is deployed you will get a bill each month from Microsoft for your Azure usage. The bill is quite detailed, and you can export the data from it to do analysis, and using methods like regression and so on project out into the future what the costs will be. I normally advise that the architect also extrapolate a unit cost from those metrics as well. This is the information that should be reported back to the executives that pay the bills: the past cost, future projected costs, and unit cost “per click” or “per transaction”, as your case warrants. The challenge here is in the model itself - statistical methods are not foolproof, and the larger the sample (in this case I recommend the entire population, not a smaller sample) is key. References and Tools Articles: http://blogs.msdn.com/b/patrick_butler_monterde/archive/2010/02/10/windows-azure-billing-overview.aspx http://technet.microsoft.com/en-us/magazine/gg213848.aspx http://blog.codingoutloud.com/2011/06/05/azure-faq-how-much-will-it-cost-me-to-run-my-application-on-windows-azure/ http://blogs.msdn.com/b/johnalioto/archive/2010/08/25/10054193.aspx http://geekswithblogs.net/iupdateable/archive/2010/02/08/qampa-how-can-i-calculate-the-tco-and-roi-when.aspx   Other Tools: http://cloud-assessment.com/ http://communities.quest.com/community/cloud_tools

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  • Windows Cloud Services Aren’t Exclusive to Microsoft

    - by Ken Cox [MVP]
    The Windows Azure brand has captured mindshare for the buzzword-du-jour, ‘cloud computing’. However, Microsoft certainly isn’t the only option for cranking up virtual machines to meet unexpected or peak demands. For example, I see that OrcsWeb has released its Windows Cloud Servers product , starting at $99.99 a month*.  Competition is a good thing - and make sure you do some cost comparisons when researching cloud resources. Some of us were unpleasantly surprised by Azure’s pricing structure...(read more)

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  • Focus On Systems Admins and Developers

    - by rickramsey
    Even if you're not going to Oracle Open World, you might find it interesting to hear what the different technology groups at Oracle are going to be talking about. And if you are going, here's your Systems schedule: Note: all links go to PDF files. Focus On: Oracle Linux Focus On: Oracle Solaris Focus On: Oracle Solaris Cluster Focus On: Oracle Solaris Studio Focus On: Desktop Virtualization Focus On: Oracle VM Server Virtualization Focus On: SPARC Servers Focus On: Storage Focus On: SPARC Supercluster - Rick Website Newsletter Facebook Twitter

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  • What is Quantum Computing? Microsoft’s video explains it in simple language

    - by Gopinath
    Quantum Computing is the next promising big thing to happen in computer science and its going to revolutionize the way we solve problem using computers. To explain the concepts of Quantum Computing to common man, Microsoft released a nice video which gives brief introduction to the concepts, explains the benefits and the work being carried out by Microsoft to make this technology research a reality. Check out this embedded video and visit Microsoft’s website for more details on Quantum Computing.

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  • Windows Azure Use Case: Agility

    - by BuckWoody
    This is one in a series of posts on when and where to use a distributed architecture design in your organization's computing needs. You can find the main post here: http://blogs.msdn.com/b/buckwoody/archive/2011/01/18/windows-azure-and-sql-azure-use-cases.aspx  Description: Agility in this context is defined as the ability to quickly develop and deploy an application. In theory, the speed at which your organization can develop and deploy an application on available hardware is identical to what you could deploy in a distributed environment. But in practice, this is not always the case. Having an option to use a distributed environment can be much faster for the deployment and even the development process. Implementation: When an organization designs code, they are essentially becoming a Software-as-a-Service (SaaS) provider to their own organization. To do that, the IT operations team becomes the Infrastructure-as-a-Service (IaaS) to the development teams. From there, the software is developed and deployed using an Application Lifecycle Management (ALM) process. A simplified view of an ALM process is as follows: Requirements Analysis Design and Development Implementation Testing Deployment to Production Maintenance In an on-premise environment, this often equates to the following process map: Requirements Business requirements formed by Business Analysts, Developers and Data Professionals. Analysis Feasibility studies, including physical plant, security, manpower and other resources. Request is placed on the work task list if approved. Design and Development Code written according to organization’s chosen methodology, either on-premise or to multiple development teams on and off premise. Implementation Code checked into main branch. Code forked as needed. Testing Code deployed to on-premise Testing servers. If no server capacity available, more resources procured through standard budgeting and ordering processes. Manual and automated functional, load, security, etc. performed. Deployment to Production Server team involved to select platform and environments with available capacity. If no server capacity available, standard budgeting and procurement process followed. If no server capacity available, systems built, configured and put under standard organizational IT control. Systems configured for proper operating systems, patches, security and virus scans. System maintenance, HA/DR, backups and recovery plans configured and put into place. Maintenance Code changes evaluated and altered according to need. In a distributed computing environment like Windows Azure, the process maps a bit differently: Requirements Business requirements formed by Business Analysts, Developers and Data Professionals. Analysis Feasibility studies, including budget, security, manpower and other resources. Request is placed on the work task list if approved. Design and Development Code written according to organization’s chosen methodology, either on-premise or to multiple development teams on and off premise. Implementation Code checked into main branch. Code forked as needed. Testing Code deployed to Azure. Manual and automated functional, load, security, etc. performed. Deployment to Production Code deployed to Azure. Point in time backup and recovery plans configured and put into place.(HA/DR and automated backups already present in Azure fabric) Maintenance Code changes evaluated and altered according to need. This means that several steps can be removed or expedited. It also means that the business function requesting the application can be held directly responsible for the funding of that request, speeding the process further since the IT budgeting process may not be involved in the Azure scenario. An additional benefit is the “Azure Marketplace”, In effect this becomes an app store for Enterprises to select pre-defined code and data applications to mesh or bolt-in to their current code, possibly saving development time. Resources: Whitepaper download- What is ALM?  http://go.microsoft.com/?linkid=9743693  Whitepaper download - ALM and Business Strategy: http://go.microsoft.com/?linkid=9743690  LiveMeeting Recording on ALM and Windows Azure (registration required, but free): http://www.microsoft.com/uk/msdn/visualstudio/contact-us.aspx?sbj=Developing with Windows Azure (ALM perspective) - 10:00-11:00 - 19th Jan 2011

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  • Bridging Virtual Networking into Real LAN on a OpenNebula Cluster

    - by user101012
    I'm running Open Nebula with 1 Cluster Controller and 3 Nodes. I registered the nodes at the front-end controller and I can start an Ubuntu virtual machine on one of the nodes. However from my network I cannot ping the virtual machine. I am not quite sure if I have set up the virtual machine correctly. The Nodes all have a br0 interfaces which is bridged with eth0. The IP Address is in the 192.168.1.x range. The Template file I used for the vmnet is: NAME = "VM LAN" TYPE = RANGED BRIDGE = br0 # Replace br0 with the bridge interface from the cluster nodes NETWORK_ADDRESS = 192.168.1.128 # Replace with corresponding IP address NETWORK_SIZE = 126 NETMASK = 255.255.255.0 GATEWAY = 192.168.1.1 NS = 192.168.1.1 However, I cannot reach any of the virtual machines even though sunstone says that the virtual machine is running and onevm list also states that the vm is running. It might be helpful to know that we are using KVM as a hypervisor and I am not quite sure if the virbr0 interface which was automatically created when installing KVM might be a problem.

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  • GlassFish cluster-targeted jdbc is not enabled

    - by Jin Kwon
    I have a GlassFish cluster. When I tried to add node and a instance, DAS saids a bunch of error messages telling Resource [ jdbc/xxxx ] of type [ jdbc ] is not enabled [#|2012-11-14T12:07:04.318+0900|SEVERE|glassfish3.1.2|javax.enterprise.system.core.com.sun.enterprise.v3.server|_ThreadID=2803;_ThreadName=Thread-2;|java.lang.StackOverflowError at java.io.FileOutputStream.writeBytes(Native Method) at java.io.FileOutputStream.write(FileOutputStream.java:318) at java.io.BufferedOutputStream.write(BufferedOutputStream.java:122) at java.io.PrintStream.write(PrintStream.java:480) at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:221) at sun.nio.cs.StreamEncoder.implFlushBuffer(StreamEncoder.java:291) at sun.nio.cs.StreamEncoder.implFlush(StreamEncoder.java:295) at sun.nio.cs.StreamEncoder.flush(StreamEncoder.java:141) at java.io.OutputStreamWriter.flush(OutputStreamWriter.java:229) at java.util.logging.StreamHandler.flush(StreamHandler.java:242) at java.util.logging.ConsoleHandler.publish(ConsoleHandler.java:106) at java.util.logging.Logger.log(Logger.java:522) at com.sun.logging.LogDomains$1.log(LogDomains.java:372) at java.util.logging.Logger.doLog(Logger.java:543) at java.util.logging.Logger.log(Logger.java:607) at com.sun.enterprise.resource.deployer.JdbcResourceDeployer.deployResource(JdbcResourceDeployer.java:117) at org.glassfish.javaee.services.ResourceProxy.create(ResourceProxy.java:90) at com.sun.enterprise.naming.impl.SerialContext.lookup(SerialContext.java:507) at com.sun.enterprise.naming.impl.SerialContext.lookup(SerialContext.java:455) at javax.naming.InitialContext.lookup(InitialContext.java:411) at javax.naming.InitialContext.lookup(InitialContext.java:411) at com.sun.appserv.connectors.internal.api.ResourceNamingService.lookup(ResourceNamingService.java:221) the JDBC Resource is ok and targeted with the cluster. I've installed the JDBC driver on the new node. Can anybody help?

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  • How To Set Up A Loadbalanced High-Availability Apache Cluster On Windows

    - by bReAd
    Setting up a two-node Apache web server cluster that provides high-availability. In front of the Apache cluster we create a load balancer that splits up incoming requests between the two Apache nodes. Because we do not want the load balancer to become another “Single Point Of Failure”, we must provide high-availability for the load balancer, too. Therefore our load balancer will in fact consist out of two load balancer nodes that monitor each other using heartbeat, and if one load balancer fails, the other takes over silently. The following setup is proposed: Apache node 1: webserver1.example.com (webserver1) – IP address: 192.168.0.101; Apache document root: /var/www Apache node 2: webserver2.example.com (webserver2) – IP address: 192.168.0.102; Apache document root: /var/www Load Balancer node 1: loadb1.example.com (loadb1) – IP address: 192.168.0.103 Load Balancer node 2: loadb2.example.com (loadb2) – IP address: 192.168.0.104 Virtual IP Address: 192.168.0.105 (used for incoming requests) Currently, there are many solutions for Linux machines and there aren't any on windows. I've tried searching a long time for solutions on Windows platform How do I create the virtual IP in windows and perform monitoring and make the load balancer listen to the virtual IP Address?

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  • Clustering/load balancing for cluster unaware applications

    - by AaronLS
    Forgive me if I use any of these terms incorrectly. I am wondering if there is any kind of software that would allow my two "join" two computers together such that a cluster unaware application could utilize their combined computing resources? By "cluster unaware" I mean an application that isn't designed to share work across multiple services. My understanding is that clustering is enabled by the specific application by it's architecture, such that messaging with multiple instances of the application coordinate the sharing of work. Instead I am looking for something that enables clustering at the OS or virtualization level, so that any application could essentially be clustered. Failing that, I am also wondering about the following scenario: We have 3 different applications we will call A, B, and C. We have 2 single core computers. At any given time lets say that any combination of those applications will be CPU intensive. In cases where only 2 of those apps are very active, have one of them moved over to a different server. In a nutshell, some sort of dynamic automatic shuffling of the application's load. I have heard of virtual machines that can be migrated across physical machines while live, but I am wondering if this can be done automatically in response to an application's or VM's CPU activity?

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  • Linux HA / cluster: what are the differences between Pacemaker, Heartbeat, Corosync, wackamole?

    - by Continuation
    Can you help me understand Linux HA? Pacemaker, Heartbeat, Corosync seem to be part of a whole HA stack, but how do they fit together? How does wackamole differ from Pacemaker/Heartbeat/Corosync? I've seen opinions that wackamole is better than Heartbeat because it's peer-based. Is that valid? The last release of wackamole was 2.5 years ago. Is it still being maintained or active? What would you recommend for HA setup for web/application/database servers?

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  • PostgreSQL failover cluster on Windows Server

    - by user36997
    We are looking for advice on how to setup a basic failover cluster for our application: We will be using 4 machines running Microsoft Windows Server (most probably 2003). All four will always run our application, which is essentially a web service. Load balancing is "outsourced" - somebody else handles the distribution of the web requests among the servers. Only one of the servers will be running the PostgreSQL server actively at any given time. Another server (of the four) also has the DB installed, but is on standby/passive. The DB data is stored on shared storage. No copying data between servers. Reads are done very frequently by many end-users, and in rather small chunks of data. Writes are done much less frequently, by less users, and in very large bulks of data. Now, how can one configure Microsoft Cluster Service to keep only one instance of the DB server and 4 instances (1 per server) of our application at all times? And does PostgreSQL integrate neatly with MSCS at all? Update: Instead of keeping the data on shared storage, I also consider using log shipping to replicate data on a couple of DB servers. There are two issues with this option: Log shipping only makes sure that I have a second server that gets all of the data and is ready to take over. How do I implement the actual failure detection and failover switch? Switching back: Suppose the master fails and the system automatically fails over to the slave, and later the master comes back online. I understand that with WAL shipping this will require to reconfigure the log shipping once again, and that switching back is far from seamless. Is that so?

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  • Virtual machines interconnection inside Proxmox 2.1 Cluster

    - by Anton
    We have 3 physical servers (each with 1 NIC) in different datacentres, all of them are interconnected by openvpn bridged private network (10.x.x.x). Inside this network we have fully functional 3 nodes Proxmox 2.1 cluster. So, actually question is: Is there any "proper" way to make "global" local network (172.16.x.x) for all VMs inside cluster, so even if we move VM from one node to other we could reach it by static IP regardless of it's physical location? BTW, we can't add dedicated NIC to each server. Thanks in advance. EDIT: I have tried to make a separate openvpn bridge for 172.16.x.x, now I have at each server two interfaces: SRV1: openvpnbr1 - 172.16.13.1 vmbr0 - 172.16.1.1 SRV2: openvpnbr1 - 172.16.13.2 vmbr0 - 172.16.2.1 But now there is no connection between those ifaces: SRV1: ping 172.16.13.2 From 172.16.1.1 icmp_seq=2 Destination Host Unreachable SRV2: ping 172.16.13.1 From 172.16.2.1 icmp_seq=2 Destination Host Unreachable If I shut down vmbr0 interfaces, so there is connection between servers over openvpn, but vmbr0 is used by Proxmox... Where I am wrong?

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  • SBD killing both cluster nodes when there are even small SAN network problems

    - by Wieslaw Herr
    I am having problems with stonith SBD in a openais-based cluster. Some background: The active/passive cluster has two nodes, node1 and node2. They are configured to provide an NFS service to users. To avoid problems with split-brain, they are both configured to use SBD. SBD is using two 1MB disks available to the hosts via an multipath fibre-channel network. The problems start if something happens with the SAN network. For example, today one of the brocade switches got rebooted and both nodes lost 2 out of 4 paths to each disks, which resulted in both nodes committing suicide and rebooting. This, of course, was highly undesirable because a) there were paths left b) even if the switch would be out for 10-20 seconds a reboot cycle of both nodes would take 5-10 minutes and all NFS-locks would be lost. I tried increasing the SBD timeout values (to 10sec+ values, dump attached at the end), however a "WARN: Latency: No liveness for 4 s exceeds threshold of 3 s" hints that something isn't working as I would it expect to. Here is what I would like to know: a) Is SBD working as it should killing nodes when 2 paths are available? b) If not, is the multipath.conf file attached correct? The storage controller we use is an IBM SVC (IBM 2145), should there be any specific configuration for it? (as in multipath.conf.defaults) c) How should I go about increasing the timeouts in SBD attachements: Multipath.conf and sbd dump (http://hpaste.org/69537)

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  • using i7 "gamer" cpu in a HPC cluster

    - by user1219721
    I'm running WRF weather model. That's a ram intensive, highly parallel application. I need to build a HPC cluster for that. I use 10GB infiniband interconnect. WRF doesn't depends of core count, but on memory bandwidth. That's why a core i7 3820 or 3930K performs better than high-grade xeons E5-2600 or E7 Seems like universities uses xeon E5-2670 for WRF. It costs about $1500. Spec2006 fp_rates WRF bench shows $580 i7 3930K performs the same with 1600MHz RAM. What's interesting is that i7 can handle up to 2400MHz ram, doing a great performance increase for WRF. Then it really outperforms the xeon. Power comsumption is a bit higher, but still less than 20€ a year. Even including additional part I'll need (PSU, infiniband, case), the i7 way is still 700 €/cpu cheaper than Xeon. So, is it ok to use "gamer" hardware in a HPC cluster ? or should I do it pro with xeon ? (This is not a critical application. I can handle downtime. I think I don't need ECC?)

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  • Setting up a global MySQL Cluster in the cloud

    - by GregB
    I'm giving the question an overhaul to more specifically identify where I need help. I use two tools to manage a bunch of cloud server: Puppet and Rundeck. Both of these can be configured to use a mysql backend. I'd like to setup an instance of each application in both the U.S., and the U.K., treating the U.K. servers as hot stand-bys in case of failure in the U.S. I want to use a MySql cluster so that the data is automatically replicated from the U.S. to the U.K. Because these are hot standbys, high performance is not a goal. Redundancy and data integrity are most important. My question revolves around the setup of the mysql cluster. I want to run three servers, each one running a data node, a sql node, and a management node. Is this a valid configuration for mysql server? If so, could someone point me in the right direction for creating such a setup? I've downloaded the offical tarball, and the official debian, and the documentation for them contradicts many of the online tutorials. I'm installing on Ubuntu 10.04.

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  • New Reference Configuration: Accelerate Deployment of Virtual Infrastructure

    - by monica.kumar
    Today, Oracle announced the availability of Oracle VM blade cluster reference configuration based on Sun servers, storage and Oracle VM software. Assembling and integrating software and hardware systems from different vendors can be a huge barrier to deploying virtualized infrastructures as it is often a complicated, time-consuming, risky and expensive process. Using this tested configuration can help reduce the time to configure and deploy a virtual infrastructure by up to 98% as compared to putting together multi-vendor configurations. Once ready, the infrastructure can be used to easily deploy enterprise applications in a matter of minutes to hours as opposed to days/weeks, by using Oracle VM Templates. Find out more: Press Release Business whitepaper Technical whitepaper

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  • Has RFC2324 been implemented?

    - by anthony-arnold
    I know RFC2324 was an April Fools joke. However, it seems pretty well thought out, and after reading it I figured it wouldn't be out of the question to design an automated coffee machine that used this extension to HTTP. We programmers love to reference this RFC when arguing web standards ("418 I'm a Teapot lolz!") but the joke's kind of on us. Ubiquitous computing research assumes that network-connected coffee machines are probably going to be quite common in the future, along with Internet-connected fruit and just about everything else. Has anyone actually implemented a coffee machine that is controlled via HTCPCP? Not necessarily commercial, but hacked together in a garage, maybe? I'm not talking about just a web server that responds to HTCPCP requests; I mean a real coffee machine that actually makes coffee. I haven't seen an example of that.

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  • Microsoft launches two new Data Centres for Azure in US to meet growing demand

    - by Gopinath
    In order to meet the growing demand for Windows Azure in US, Microsoft has launched two new data centres in US – East US and West US. With the addition of these two data centres the number of Azure data centres across the globe has grown to 8 and 4 among them are located in US. The two new data centres are providing Computer and Storage resources and few enthusiastic customers already deployed their applications. The other services like SQL Azure and AppFabric will be offered by these data centres in the coming months. The addition of new data centres is a good sign to Microsoft as the customer demand for their Cloud offering is growing. Amazon Web Services is the pioneer in Cloud Computing and they offer wider range of Cloud Services compared to Microsoft. Source: Windows Azure Blog

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  • Synchronizing local and remote cache in distributed caching

    - by ltfishie
    With a distributed cache, a subset of the cache is kept locally while the rest is held remotely. In a get operation, if the entry is not available locally, the remote cache will be used and and the entry is added to local cache. In a put operation, both the local cache and remote cache are updated. Other nodes in the cluster also need to be notified to invalidate their local cache as well. What's a simplest way to achieve this if you implemented it yourself, assuming that nodes are not aware of each other. Edit My current implementation goes like this: Each cache entry contains a time stamp. Put operation will update local cache and remote cache Get operation will try local cache then remote cache A background thread on each node will check remote cache periodically for each entry in local cache. If the timestamp on remote is newer overwrite the local. If entry is not found in remote, delete it from local.

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  • Using Resources the Right Way

    - by BuckWoody
    It’s an interesting time in computing technology. At one point there was a dearth of information available for solving a given problem, or educating ourselves on broader topics so that we can solve problems in the future. With dozens, perhaps hundreds or thousands of web sites and content available (for free, in many cases) from vendors, peers, even colleges and universities, it seems like there is actually too much information. Who has the time to absorb all this information and training? Even if you had the inclination, where to start? In fact, it seems so overwhelming that I often hear people saying that they can’t find the training they need, or that vendor X or Y “doesn’t help their users”. On questioning these folks, however, I often find that they – and sometimes I - haven’t put in the effort to learn what resources we have. That’s where blogs, like this one, can help. If you follow a blog, either by checking it often or perhaps subscribing to the Really Simple Syndication (RSS) feed, you’ll be able to spread out the search or create a mental filter for the information you need. But it’s not enough just read a blog or a web page. The creators need real feedback – what doesn’t work, and what does. Yes, you’re allowed to tell a vendor or writer “This helped me because…” so that you reinforce the positives. To be sure, bring up what doesn’t work as well –  that’s fine. But be specific, and be constructive. You’d be surprised at how much it matters. I know for a fact at Microsoft we listen – there is a real live person that reads your comments. I’m sure this is true of other vendors, and I also know that most blog authors – yours truly most especially – wants to know what you think.   In this blog entry I’d to call your attention to three resources you have at your disposal, and how you can use them to help. I’ll try to bring up things like this from time to time that I find useful, and cover in them in more depth like this. Think of this as a synopsis of a longer set of resources that you can use to filter whether you want to research further, bookmark, or forward on to a circle of friends where you think it might help them.   Data Driven Design Concepts http://msdn.microsoft.com/en-us/library/windowsazure/jj156154 I’ll start with a great site that walks you through the process of designing a solution from a data-first perspective. As you know, I believe all computing is merely re-arranging data. If you follow that logic as well, you’ll realize that whenever you create a solution, you should start at the data-end of the application. This resource helps you do that. Even if you don’t use the specific technologies the instructions use, the concepts hold for almost any other technology that deals with data. This should be a definite bookmark for a developer, DBA, or Data Architect. When I mentioned my admiration for this resource here at Microsoft, the team that created it contacted me and asked if I’d share an e-mail address to my readers so that you can comment on it. You’re guaranteed to be heard – you can suggest changes, talk about how useful – or not – it is, and so on. Here’s that address:  [email protected]   End-to-End Example of a complete Hybrid Application – with Live Demo https://azurestocktrader.cloudapp.net/Default.aspx I learn by example. I also like having ready-made, live, functional demos that show the completed solution at work. If you’ve ever wanted to learn how a complex, complete, hybrid application that bridges on-premises systems with cloud-based databases, code, functions and more, this is it. It’s a stock-trading simulator, and you can get everything from the design to the code itself, or you can just play with the application. It’s running on Windows Azure, the actual production servers we use for everything else. Using a Cloud-Based Service https://azureconfigweb.cloudapp.net/Default.aspx Along with that stock-trading application, you have a full demonstration and usable code sample of a web-based service available. If you’re a developer, this is a style of code you need to understand for everything from iPhone development to a full Service-Oriented Architecture (SOA) environment. So check out these resources. I’ll post more from time to time as I run across them. Hopefully they’ll be as useful to you as they are to me. Oh, and if you have a comment on any of the resources, let them know. And if you have any comments about these or any of my entries, feel free to post away. To quote a famous TV Show: “Hello Seattle – I’m listening…”

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  • Using Openfire for distributed XMPP-based video-chat

    - by Yitzhak
    I have been tasked with setting up a distributed video-chat system built on XMPP. Currently my setup looks like this: Openfire (XMPP server) + JingleNodes plugin for video chat OpenLDAP (LDAP server) for storing user information and allowing directory queries Kerberos server for authentication and passwords In testing with one set of machines (i.e. only three), everything works as expected: I can log in to Openfire and it looks up the user information in the OpenLDAP database, which in turn authenticates my user with Kerberos. Now, I want to have several clusters, so that there is a cluster on each continent. A typical cluster will probably contain 2-5 servers. Users logging in will be directed to the closest cluster based on geographical location. Something that concerns me particularly is the dynamic maintenance of contact lists. If a user is using a machine in Asia, for example, how would contact lists be updated around the world to reflect the current server he is using? How would that work with LDAP? Specific questions: How do I direct users based on geographical location? What is the best architecture for a cluster? -- would all traffic need to come into a load-balancer on each one, for example? How do I manage the update of contact lists across all these servers? In general, how do I go about setting this up? What are the pitfalls in doing this? I am inexperienced in this area, so any advice and suggestions would be appreciated.

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  • What is the optimum way to select the most dissimilar individuals from a population?

    - by Aaron D
    I have tried to use k-means clustering to select the most diverse markers in my population, for example, if we want to select 100 lines I cluster the whole population to 100 clusters then select the closest marker to the centroid from each cluster. The problem with my solution is it takes too much time (probably my function needs optimization), especially when the number of markers exceeds 100000. So, I will appreciate it so much if anyone can show me a new way to select markers that maximize diversity in my population and/or help me optimize my function to make it work faster. Thank you # example: library(BLR) data(wheat) dim(X) mdf<-mostdiff(t(X), 100,1,nstart=1000) Here is the mostdiff function that i used: mostdiff <- function(markers, nClust, nMrkPerClust, nstart=1000) { transposedMarkers <- as.array(markers) mrkClust <- kmeans(transposedMarkers, nClust, nstart=nstart) save(mrkClust, file="markerCluster.Rdata") # within clusters, pick the markers that are closest to the cluster centroid # turn the vector of which markers belong to which clusters into a list nClust long # each element of the list is a vector of the markers in that cluster clustersToList <- function(nClust, clusters) { vecOfCluster <- function(whichClust, clusters) { return(which(whichClust == clusters)) } return(apply(as.array(1:nClust), 1, vecOfCluster, clusters)) } pickCloseToCenter <- function(vecOfCluster, whichClust, transposedMarkers, centers, pickHowMany) { clustSize <- length(vecOfCluster) # if there are fewer than three markers, the center is equally distant from all so don't bother if (clustSize < 3) return(vecOfCluster[1:min(pickHowMany, clustSize)]) # figure out the distance (squared) between each marker in the cluster and the cluster center distToCenter <- function(marker, center){ diff <- center - marker return(sum(diff*diff)) } dists <- apply(transposedMarkers[vecOfCluster,], 1, distToCenter, center=centers[whichClust,]) return(vecOfCluster[order(dists)[1:min(pickHowMany, clustSize)]]) } }

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  • Significant new inventions in computing since 1980

    - by Alan Kay
    This question arose from comments about different kinds of progress in computing over the last 50 years or so. I was asked by some of the other participants to raise it as a question to the whole forum. Basic idea here is not to bash the current state of things but to try to understand something about the progress of coming up with fundamental new ideas and principles. I claim that we need really new ideas in most areas of computing, and I would like to know of any important and powerful ones that have been done recently. If we can't really find them, then we should ask "Why?" and "What should we be doing?"

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  • Pros and cons of cloud computing?

    - by Vimvq1987
    After 3 months of research, my thesis is nearly complete. Now I'm writing the report. Interesting parts are finished, now the boring and hard-to-write parts. I need to write about pros and cons of cloud computing. What it gives us and what it take us. I've searched much but there's only list, no explains. So I need your helps, to list and explains all of pros and cons of cloud computing. Thank you so much for this.

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