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  • Heading in the Right Direction: Garmin Exadata adoption

    - by Javier Puerta
    A pioneer in global positioning system (GPS) navigation, Garmin International Inc. has been adopting Exadata to support the infrastructure that powered the company’s Oracle Advanced Supply Chain Planning, but also the company’s fitness segment, which provides customers with an online platform to store, retrieve, and interact with data captured using Garmin fitness products. The environment, which is built on an Oracle Database, processes approximately 40 million queries per week. Prior to using Oracle Exadata Database Machine, as the online offering grew in popularity, it began to face reliability issues that had negatively impacted the customer experience. We included the video testimonial in a previous post. Now you can find the a complete set of materials about this customer story Garmin Customer Reference Garmin video testimonial:  Garmin Consolidates on Exadata for 50% Performance Boost Profit Magazine article:  Heading in the Right Direction

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  • Oracle OpenWorld Update -- Scaling Infrastructure to Meet Business Growth: A Coherence Customer Panel

    - by Ruma Sanyal
    Today being the Monday of OpenWorld is packed with great content and sessions. I have already blogged about the general session by Ajay Patel and the classic Cloud Application Foundation roadmap and strategy session by Mike Lehmann. But we will be remiss if we don’t list the customer panel for Coherence. Come listen to customers spanning a wide variety of industries such as consumer goods, railways, and agricultural biotechnology discuss how Oracle Coherence enables business growth, cost cutting, and improved customer experience. You will learn how Coherence helps scale services cost-effectively, improve performance, and assure service availability in both on-premises and cloud deployments. Each customer will present details of their specific use cases, benefits and war stories of developing, deploying and managing some of the largest data grid deployments in the world. The session will be moderated by Cameron Purdy, VP of Development, and Mr. Coherence himself J For more information about this and other Coherence sessions, review the Coherence Focus on document. Details: Monday, 10/1, 12:15 p.m. - 1:15 p.m., Moscone South Room 309

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  • Topeka Dot Net User Group (DNUG) Meeting &ndash; April 6, 2010

    Topeka DNUG is free for anyone to attend! Mark your calendars now! SPEAKER: Troy Tuttle is a self-described pragmatic agilist, and Kanban practitioner, with more than a decade of experience in delivering software in the finance and health industries and as a consultant. He advocates teams improve their performance through pursuit of better practices like continuous integration and automated testing. Troy is the founder of the Kansas City Limited WIP Society and is a speaker at local area groups...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Moving from XNA/C# to DirectX/C++ quite confused

    - by misiMe
    I made some game with XNA/C# for Windows Phone and Windows 8, since XNA is dead and Visual studio doesn't support it (I have to target Windows Phone 7.1 to build with XNA), I want to start learning something more "consistent in time" and improve my skills. I'm a little confused about the possibilities, because C++/DirectX alone seems difficult, so I found some high-level classes to help: DirectX Toolkit Cocos2D My questions are: What will happen when they will "die" like XNA? Is C++'s approces more "professional" than C#/XNA and why? Is C++'s approces more "portable"? Is C++'s approces more resistant in terms of time? Is there any consideration about DirectX TK and Cocos2D in terms of performance? I ask that because I found that every Game software house in my country looks for skilled C++ programmers.

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  • Oracle SOA Suite 11g Administrator's Handbook

    - by Antony Reynolds
    SOA Administration Book I have just received a copy of the “Oracle SOA Suite 11g Administrator's Handbook” so as soon as I have read it I will let you know what I think.  In the meantime the first thing that struck me was the author credentials, although I have never met either of them as I remember, I have read Admeds blog postings and they are a great community resource, so immediately I am well disposed towards the book.  Similarly Arun is an employee of my friend and co-author Matt Wright, and I have heard good things about him from Rubicon Red people. A first glance at the table of contents looks encouraging, I particularly like their approach to performance tuning where they give a clear concise explanation of the knobs they are using. More when I have read more.

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  • 25. Treffen der FraOSUG am 18. September 2012

    - by uligraef
    Zum 25. Treffen der FraOSUG (Frankfurter Open Solaris / Solaris / Oracle Solaris Users Group) treffen wir uns erstmals in den Räumlichkeiten der Geschäftstelle in Dreieich. Wann? 18. September 2012, 18:00 - 21:00 Uhr Wo? Oracle, Geschäftsstelle Frankfurt, Robert Bosch Str. 5, 63303 Dreieich Agenda: Begrüßung Optimale Datenkompression kleiner Datenmengen mit Suffix Arrays Nachdem neulich Interesse bekundet wurde wird hier der Vortrag vom mrmcd12 wiederholt.(Ulrich Gräf) Roundtable: ZFS Performance -- Die Diskussion zum Vortrag vom letzten Mal (Alle) Diskussion(alle)  Anmeldung bitte mit Doodle . Mehr siehe auf der FraOSUG Homepage.

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  • Finally found a replacement for my.live.com&hellip;

    - by eddraper
    As I had alluded to before, the transition of http://my.live.com/ to http://my.msn.com/ caused me serious grief. I've been an RSS addict for many, many years and I found the my.live.com UI to be the ultimate RSS reader and gateway to the web. It had been my home page for a long time.  My.msn has a LONG way to go before it matches the elegance and performance of my.live. The site I ended up going with is http://www.netvibes.com/ .   It’s the closest thing I could find that could do four column tiles with a reasonable amount of information density .  I’d still prefer a lot less “chrome” and better use of space, but it’s as close as I’m going to get… One feature I really do like about netvibes, is the pagination feature.  The built in feed reader is also quite nice… All-in-all, I’d recommend netvibes…

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  • Order independent transparency in particle system

    - by Stepan Zastupov
    I'm writing a particle system and would like to find a trick to achieve proper alpha blending without sorting particles because: Each particle is a point sprite in a single mesh and I can't use scene graph ability to sort transparent nodes. The system node should be properly sorted, though. Particle position is computed on shader from initial velocity, acceleration and time. In order to sort the system I would have to perform all this computations on CPU, which is something I want to avoid. Sorting hundreds of particles against camera position and uploading it on GPU each frame seams to be quiet heavy operation. Alpha testing seems to be fast enough on GLES 2.0 and works fine for non-transparent but "masked" textures. Still, it's not enough for semi-transparent particles. How would you handle this?

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  • Is Data Science “Science”?

    - by BuckWoody
    I hold the term “science” in very high esteem. I grew up on the Space Coast in Florida, and eventually worked at the Kennedy Space Center, surrounded by very intelligent people who worked in various scientific fields. Recently a new term has entered the computing dialog – “Data Scientist”. Since it’s not a standard term, it has a lot of definitions, and in fact has been disputed as a correct term. After all, the reasoning goes, if there’s no such thing as “Data Science” then how can there be a Data Scientist? This argument has been made before, albeit with a different term – “Computer Science”. In Peter Denning’s excellent article “Is Computer Science Science” (April  2005/Vol. 48, No. 4 COMMUNICATIONS OF THE ACM) there are many points that separate “science” from “engineering” and even “art”.  I won’t repeat the content of that article here (I recommend you read it on your own) but will leverage the points he makes there. Definition of Science To ask the question “is data science ‘science’” then we need to start with a definition of terms. Various references put the definition into the same basic areas: Study of the physical world Systematic and/or disciplined study of a subject area ...and then they include the things studied, the bodies of knowledge and so on. The word itself comes from Latin, and means merely “to know” or “to study to know”. Greek divides knowledge further into “truth” (episteme), and practical use or effects (tekhne). Normally computing falls into the second realm. Definition of Data Science And now a more controversial definition: Data Science. This term is so new and perhaps so niche that the major dictionaries haven’t yet picked it up (my OED reference is older – can’t afford to pop for the online registration at present). Researching the term's general use I created an amalgam of the definitions this way: “Studying and applying mathematical and other techniques to derive information from complex data sets.” Using this definition, data science certainly seems to be science - it's learning about and studying some object or area using systematic methods. But implicit within the definition is the word “application”, which makes the process more akin to engineering or even technology than science. In fact, I find that using these techniques – and data itself – part of science, not science itself. I leave out the concept of studying data patterns or algorithms as part of this discipline. That is actually a domain I see within research, mathematics or computer science. That of course is a type of science, but does not seek for practical applications. As part of the argument against calling it “Data Science”, some point to the scientific method of creating a hypothesis, testing with controls, testing results against the hypothesis, and documenting for repeatability.  These are not steps that we often take in working with data. We normally start with a question, and fit patterns and algorithms to predict outcomes and find correlations. In this way Data Science is more akin to statistics (and in fact makes heavy use of them) in the process rather than starting with an assumption and following on with it. So, is Data Science “Science”? I’m uncertain – and I’m uncertain it matters. Even if we are facing rampant “title inflation” these days (does anyone introduce themselves as a secretary or supervisor anymore?) I can tolerate the term at least from the intent that we use data to study problems across a wide spectrum, rather than restricting it to a single domain. And I also understand those who have worked hard to achieve the very honorable title of “scientist” who have issues with those who borrow the term without asking. What do you think? Science, or not? Does it matter?

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  • jqGrid - dynamically load different drop down values for different rows depending on another column value

    - by Renso
    Goal: As we all know the jqGrid examples in the demo and the Wiki always refer to static values for drop down boxes. This of course is a personal preference but in dynamic design these values should be populated from the database/xml file, etc, ideally JSON formatted. Can you do this in jqGrid, yes, but with some custom coding which we will briefly show below (refer to some of my other blog entries for a more detailed discussion on this topic). What you CANNOT do in jqGrid, referrign here up and to version 3.8.x, is to load different drop down values for different rows in the jqGrid. Well, not without some trickery, which is what this discussion is about. Issue: Of course the issue is that jqGrid has been designed for high performance and thus I have no issue with them loading a  reference to a single drop down values list for every column. This way if you have 500 rows or one, each row only refers to a single list for that particuolar column. Nice! SO how easy would it be to simply traverse the grid once loaded on gridComplete or loadComplete and simply load the select tag's options from scratch, via ajax, from memory variable, hard coded etc? Impossible! Since their is no embedded SELECT tag within each cell containing the drop down values (remeber it only has a reference to that list in memory), all you will see when you inspect the cell prior to clicking on it, or even before and on beforeEditCell, is an empty <TD></TD>. When trying to load that list via a click event on that cell will temporarily load the list but jqGrid's last internal callback event will remove it and replace it with the old one, and you are back to square one. Solution: Yes, after spending a few hours on this found a solution to the problem that does not require any updates to jqGrid source code, thank GOD! Before we get into the coding details, the solution here can of course be customized to suite your specific needs, this one loads the entire drop down list that would be needed across all rows once into global variable. I then parse this object that contains all the properties I need to filter the rows depending on which ones I want the user to see based off of another cell value in that row. This only happens when clicking the cell, so no performance penalty. You may of course to load it via ajax when the user clicks the cell, but I found it more effecient to load the entire list as part of jqGrid's normal editoptions: { multiple: false, value: listingStatus } colModel options which again keeps only a reference to the sinlge list, no duplciation. Lets get into the meat and potatoes of it.         var acctId = $('#Id').val();         var data = $.ajax({ url: $('#ajaxGetAllMaterialsTrackingLookupDataUrl').val(), data: { accountId: acctId }, dataType: 'json', async: false, success: function(data, result) { if (!result) alert('Failure to retrieve the Alert related lookup data.'); } }).responseText;         var lookupData = eval('(' + data + ')');         var listingCategory = lookupData.ListingCategory;         var listingStatus = lookupData.ListingStatus;         var catList = '{';         $(lookupData.ListingCategory).each(function() {             catList += this.Id + ':"' + this.Name + '",';         });         catList += '}';         var lastsel;         var ignoreAlert = true;         $(item)         .jqGrid({             url: listURL,             postData: '',             datatype: "local",             colNames: ['Id', 'Name', 'Commission<br />Rep', 'Business<br />Group', 'Order<br />Date', 'Edit', 'TBD', 'Month', 'Year', 'Week', 'Product', 'Product<br />Type', 'Online/<br />Magazine', 'Materials', 'Special<br />Placement', 'Logo', 'Image', 'Text', 'Contact<br />Info', 'Everthing<br />In', 'Category', 'Status'],             colModel: [                 { name: 'Id', index: 'Id', hidden: true, hidedlg: true },                 { name: 'AccountName', index: 'AccountName', align: "left", resizable: true, search: true, width: 100 },                 { name: 'OnlineName', index: 'OnlineName', align: 'left', sortable: false, width: 80 },                 { name: 'ListingCategoryName', index: 'ListingCategoryName', width: 85, editable: true, hidden: false, edittype: "select", editoptions: { multiple: false, value: eval('(' + catList + ')') }, editrules: { required: false }, formatoptions: { disabled: false} }             ],             jsonReader: {                 root: "List",                 page: "CurrentPage",                 total: "TotalPages",                 records: "TotalRecords",                 userdata: "Errors",                 repeatitems: false,                 id: "0"             },             rowNum: $rows,             rowList: [10, 20, 50, 200, 500, 1000, 2000],             imgpath: jQueryImageRoot,             pager: $(item + 'Pager'),             shrinkToFit: true,             width: 1455,             recordtext: 'Traffic lines',             sortname: 'OrderDate',             viewrecords: true,             sortorder: "asc",             altRows: true,             cellEdit: true,             cellsubmit: "remote",             cellurl: editURL + '?rows=' + $rows + '&page=1',             loadComplete: function() {               },             gridComplete: function() {             },             loadError: function(xhr, st, err) {             },             afterEditCell: function(rowid, cellname, value, iRow, iCol) {                 var select = $(item).find('td.edit-cell select');                 $(item).find('td.edit-cell select option').each(function() {                     var option = $(this);                     var optionId = $(this).val();                     $(lookupData.ListingCategory).each(function() {                         if (this.Id == optionId) {                                                       if (this.OnlineName != $(item).getCell(rowid, 'OnlineName')) {                                 option.remove();                                 return false;                             }                         }                     });                 });             },             search: true,             searchdata: {},             caption: "List of all Traffic lines",             editurl: editURL + '?rows=' + $rows + '&page=1',             hiddengrid: hideGrid   Here is the JSON data returned via the ajax call during the jqGrid function call above (NOTE it must be { async: false}: {"ListingCategory":[{"Id":29,"Name":"Document Imaging & Management","OnlineName":"RF Globalnet"} ,{"Id":1,"Name":"Ancillary Department Hardware","OnlineName":"Healthcare Technology Online"} ,{"Id":2,"Name":"Asset Tracking","OnlineName":"Healthcare Technology Online"} ,{"Id":3,"Name":"Asset Tracking","OnlineName":"Healthcare Technology Online"} ,{"Id":4,"Name":"Asset Tracking","OnlineName":"Healthcare Technology Online"} ,{"Id":5,"Name":"Document Imaging & Management","OnlineName":"Healthcare Technology Online"} ,{"Id":6,"Name":"Document Imaging & Management","OnlineName":"Healthcare Technology Online"} ,{"Id":7,"Name":"EMR/EHR Software","OnlineName":"Healthcare Technology Online"}]} I only need the Id and Name for the drop down list, but the third column in the JSON object is important, it is the only that I match up with the OnlineName in the jqGrid column, and then in the loop during afterEditCell simply remove the ones I don't want the user to see. That's it!

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  • Two new features in November 2009 CTP

    - by kaleidoscope
    Windows Azure Diagnostics Managed Library: The new Diagnostics API enables logging using standard .NET APIs. The Diagnostics API provides built-in support for collecting standard logs and diagnostic information, including the Windows Azure logs, IIS 7.0 logs, Failed Request logs, crash dumps, Windows Event logs, performance counters, and custom logs. Variable-size Virtual Machines (VMs): Developers may now specify the size of the virtual machine to which they wish to deploy a role instance, based on the role's resource requirements. The size of the VM determines the number of CPU cores, the memory capacity, and the local file system size allocated to a running instance. e.g.: <WebRole name=”WebRole1” vmsize=”ExtraLarge”> Supported values for the ‘vmsize’ are: 1. Small 2. Medium 3. Large 4.       ExtraLarge More information for Diagnostics Managed Library can be found at: http://msdn.microsoft.com/en-us/library/ee758705.aspx   Girish, A

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  • Issues with the intended behavior of a Service layer?

    - by Rafael Cichocki
    This analysis makes sense, and states anything that avoids code duplication and simplifies maintenance speaks for a service layer. What is the technical behavior? When a service client references a service, does it do so at runtime, or does it happen at compile time? When I change something in the service layer code, will this change be automatically taken into account in all it's clients, or do they need to be individually recompiled? How does this make sense from a testing point of view - I have working code, based on some code from a service, but if that service changes, my code might break?!

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  • Exalytics Disaster Recovery

    - by Saresh
    Q:Where can you find more information about Exalytics Disaster Recovery? Ans: Exalytics Disaster Recovery: http://docs.oracle.com/cd/E41246_01/bi.1/e39709/admin_dr.htm#BABCFGEC Note 1568360.1 -Oracle Exalytics Deployment Guide (Download the whitepaper attached to the Note) OBIEE http://docs.oracle.com/cd/E28280_01/bi.1111/e10541/backup.htm#CHDFEIGF Note 1316073.1 - OBIEE 11g: Recommended Strategies For Disaster Recovery or Backup Oracle Hyperion EPM http://docs.oracle.com/cd/E17236_01/epm.1112/epm_high_avail_11121.pdf (Though this is for Hyperion EPM 11.1.2.1, it is applicable to 11.1.2.2 as well) TimesTen: http://docs.oracle.com/cd/E21901_01/doc/timesten.1122/e21632/migrate.htmhttp://docs.oracle.com/cd/E21901_01/doc/timesten.1122/e21635/standbycache.htm#CBAJDJBD EPM Disaster Recovery : http://www.oracle.com/technetwork/middleware/bi-foundation/epm-dr-best-practice-130229.ppt Oracle® Enterprise Performance Management System Backup and Recovery Guide :http://docs.oracle.com/cd/E17236_01/epm.1112/epm_backup_recovery_1112200.pdf

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  • Developer Day - Hands-on Oracle 11g Applications Developmen

    - by [email protected]
    Developer Day - Hands-on Oracle 11g Applications DevelopmentSpend a day with us learning the key tools, frameworks, techniques, and best practices for building database-backed applications. Gain hands-on experience developing database-backed applications with innovative and performance-enhancing methods. Meet, learn from, and network with Oracle database application development experts and your peers. Get a chance to win a Flip video camera and Oracle prizes, and enjoy post-event benefits such as advanced lab content downloads.Bring your own laptop (Windows, Linux, or Mac with minimum 2Gb RAM) and take away scripts, labs, and applications*.Space is limited. "Register Now"  for this FREE event. Don't miss your exclusive opportunity to meet with Oracle application development & database experts, win Oracle Trainings, and discuss today's most vital application development topics.Information how to register soon.

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  • Calling all developers building ASP.NET applications

    - by Laila Lotfi
    We know that developers building desktop apps have to contend with memory management issues, and we’d like to learn more about the memory challenges ASP.NET developers are facing. To be more specific, we’re carrying out some exploratory research leading into the next phase of development on ANTS Memory Profiler, and our development team would love to speak to developers building ASP.NET applications. You don’t need to have ever used ANTS profiler – this will be a more general conversation about: - your current site architecture, and how you manage the memory requirements of your applications on your back-end servers and web services. - how you currently diagnose memory leaks and where you do this (production server, or during testing phase, or if you normally manage to get them all during the local development). - what specific memory problems you’ve experienced – if any. Of course, we’ll compensate you for your time with a $50 Amazon voucher (or equivalent in other currencies), and our development team’s undying gratitude. If you’d like to participate, please just drop me a line on [email protected].

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  • Help me get started in TDD for web development

    - by Snow_Mac
    I've done a tiny, tiny bit of TDD in building an app for a company that I interned with. We used lots of mocking and wrote lots of assert statements, after reading lots of blogs, I'm convinced that TDD is the way to go, but how do you go about TDD web applications? My main framework is Yii in PHP. My main questions are: What do you test? Models? Controllers? Views? How do you know if the output is correct? All my web apps interact with a DB, are there cavets to that and gotchas? Can I do testing in Netbeans? Can you test form elements or just strictly objects & methods?

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  • Oracle's Business Analytics Strategy Webcast

    - by Rob Reynolds
    Join Mark Hurd and Balaji Yelamanchili as they unveil the latest advances in Oracle’s strategy for placing analytics into the hands of every one of your decision-makers—so that they can see more, think smarter, and act faster. Learn about the latest developments in business intelligence technology and applications, advanced analytics, performance management applications, and engineered systems. You’ll find out how you can harness the exploding volumes of data being generated inside your organization—and beyond the firewall—to: Deliver real-time intelligence to your mobile workforce globally Forecast and plan at the speed of business Accelerate your financial close and reporting process Discover how Oracle business analytics can change the way you do business. Register today for this on demand event.

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  • How can I get the business analysts more involved in BDD?

    - by Robert S.
    I am a proponent of Behavior Driven Development, mainly with Cucumber and RSpec, and at my current gig (a Microsoft shop) I am introducing SpecFlow as a tool to help with testing. I'd like to get the business analysts on my team involved in writing the features and scenarios, but they are put off by the "technical" aspect of it, meaning creating the files in Visual Studio (or even having Visual Studio on their machines). They want to know if we can put all the scenarios for a feature in Jira. What I'm looking for is suggestions for a workflow that will work well with BA types that are accustomed to project management/work tracking tools like Jira (we also use Greenhopper).

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  • How to perform efficient 2D picking in HTML5?

    - by jSepia
    I'm currently using an R-Tree for both picking and collision testing. Each entity on screen has a bounding box for collisions and a separate one for picking. Since entities may change position very frequently, both trees must be updated/reordered once per frame. While this is very efficient for collisions, because the tree is used in hundreds of collision queries every frame, I'm finding it too costly for picking, because it only gets queried when the user clicks, thus leading to a lot of wasted tree updates. What would be a more efficient way to implement picking without as much overhead?

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  • Browser based UI Customization with Oracle Identity Management 11gR2

    - by B Shashikumar
    Business users need user interfaces that are not only friendly but also easily customizable. However the downside of any customization project is the cost and complexity involved in developing, testing, deploying, and managing custom code. And equally critical is the challenge of ensuring customizations stay intact through product upgrades.To overcome these challenges, Oracle Identity Management 11gR2 now includes a Durable UI Configuration Framework which lets customers make complex UI customizations all from with the confines of a web browser. I recently sat down with Clayton Donley, Senior Director of Development for Oracle Identity and Access Management products. In this podcast, we examine how this new capability in Oracle Identity Management around browser based UI customization can reduce costs and complexity of customization while simplifying self service integration with corporate portal strategies. Click here to listen.

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  • Using RSYNC to Replicate Synology NAS DS710+ to Windows 7 Hard Drive

    Learn how to use a local backup drive on your windows 7 system to replicate the data on any or all of your directories on your Synology NAS (Network Hard Drive Device) DS710+.  This post will... This site is a resource for asp.net web programming. It has examples by Peter Kellner of techniques for high performance programming...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • How are minimum system requirements determined?

    - by Michael McGowan
    We've all seen countless examples of software that ships with "minimum system requirements" like the following: Windows XP/Vista/7 1GB RAM 200 MB Storage How are these generally determined? Obviously sometimes there are specific constraints (if the program takes 200 MB on disk then that is a hard requirement). Aside from those situations, many times for things like RAM or processor it turns out that more/faster is better with no hard constraint. How are these determined? Do developers just make up numbers that seem reasonable? Does QA go through some rigorous process testing various requirements until they find the lowest settings with acceptable performance? My instinct says it should be the latter but is often the former in practice.

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  • NorCal Weekly .Net is Up Now! Catch All for the .Net Events in Northern California!

      Ive always wanted a place that I could look through to find what .net events are going on in Northern California.  Ive found that there is a core group of people with common interested... This site is a resource for asp.net web programming. It has examples by Peter Kellner of techniques for high performance programming...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Neue Marketing Kits für Hardware

    - by A&C Redaktion
    Zur Vertriebsunterstützung gibt es jetzt auch Oracle Marketing Kits in Deutsch für folgende Hardware-Lösungen: Server & Storage: Improve Database Capacity Management with Oracle Storage and Hybrid Columnar Compression Server & Storage: Accelerating Database Test & Development with Sun ZFS Storage Appliance Server & Storage: Upgrade SAN Storage to Oracle Pillar Axiom Server & Storage: SPARC Refresh with Oracle Solaris Operating System Server & Storage: SPARC Server Refresh: The Next Level of Datacenter Performance with Oracle’s New SPARC Servers Server & Storage: Oracle Server Virtualization Server & Storage: Oracle Desktop Virtualization

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  • CPU Usage in Very Large Coherence Clusters

    - by jpurdy
    When sizing Coherence installations, one of the complicating factors is that these installations (by their very nature) tend to be application-specific, with some being large, memory-intensive caches, with others acting as I/O-intensive transaction-processing platforms, and still others performing CPU-intensive calculations across the data grid. Regardless of the primary resource requirements, Coherence sizing calculations are inherently empirical, in that there are so many permutations that a simple spreadsheet approach to sizing is rarely optimal (though it can provide a good starting estimate). So we typically recommend measuring actual resource usage (primarily CPU cycles, network bandwidth and memory) at a given load, and then extrapolating from those measurements. Of course there may be multiple types of load, and these may have varying degrees of correlation -- for example, an increased request rate may drive up the number of objects "pinned" in memory at any point, but the increase may be less than linear if those objects are naturally shared by concurrent requests. But for most reasonably-designed applications, a linear resource model will be reasonably accurate for most levels of scale. However, at extreme scale, sizing becomes a bit more complicated as certain cluster management operations -- while very infrequent -- become increasingly critical. This is because certain operations do not naturally tend to scale out. In a small cluster, sizing is primarily driven by the request rate, required cache size, or other application-driven metrics. In larger clusters (e.g. those with hundreds of cluster members), certain infrastructure tasks become intensive, in particular those related to members joining and leaving the cluster, such as introducing new cluster members to the rest of the cluster, or publishing the location of partitions during rebalancing. These tasks have a strong tendency to require all updates to be routed via a single member for the sake of cluster stability and data integrity. Fortunately that member is dynamically assigned in Coherence, so it is not a single point of failure, but it may still become a single point of bottleneck (until the cluster finishes its reconfiguration, at which point this member will have a similar load to the rest of the members). The most common cause of scaling issues in large clusters is disabling multicast (by configuring well-known addresses, aka WKA). This obviously impacts network usage, but it also has a large impact on CPU usage, primarily since the senior member must directly communicate certain messages with every other cluster member, and this communication requires significant CPU time. In particular, the need to notify the rest of the cluster about membership changes and corresponding partition reassignments adds stress to the senior member. Given that portions of the network stack may tend to be single-threaded (both in Coherence and the underlying OS), this may be even more problematic on servers with poor single-threaded performance. As a result of this, some extremely large clusters may be configured with a smaller number of partitions than ideal. This results in the size of each partition being increased. When a cache server fails, the other servers will use their fractional backups to recover the state of that server (and take over responsibility for their backed-up portion of that state). The finest granularity of this recovery is a single partition, and the single service thread can not accept new requests during this recovery. Ordinarily, recovery is practically instantaneous (it is roughly equivalent to the time required to iterate over a set of backup backing map entries and move them to the primary backing map in the same JVM). But certain factors can increase this duration drastically (to several seconds): large partitions, sufficiently slow single-threaded CPU performance, many or expensive indexes to rebuild, etc. The solution of course is to mitigate each of those factors but in many cases this may be challenging. Larger clusters also lead to the temptation to place more load on the available hardware resources, spreading CPU resources thin. As an example, while we've long been aware of how garbage collection can cause significant pauses, it usually isn't viewed as a major consumer of CPU (in terms of overall system throughput). Typically, the use of a concurrent collector allows greater responsiveness by minimizing pause times, at the cost of reducing system throughput. However, at a recent engagement, we were forced to turn off the concurrent collector and use a traditional parallel "stop the world" collector to reduce CPU usage to an acceptable level. In summary, there are some less obvious factors that may result in excessive CPU consumption in a larger cluster, so it is even more critical to test at full scale, even though allocating sufficient hardware may often be much more difficult for these large clusters.

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