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  • Good resource for studying Database High Availability techniques

    - by Invincible
    Hello Can anybody suggest some good resource/book on Database high availability techniques? Moreover, High-availability of system software like Intrusion Prevention system or Web servers. I am considering high-availability is global term which covers clustring, cloud computing, replication, replica management, distributed synchronization for cluster. Thanks in advance!

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  • SQL – Building a High Traffic, Profitable Blog – A Unique Gift on Author’s Birthday

    - by Pinal Dave
    Every July 30th, I like to do something new. It is my birthday and I like to give gifts to everyone this day. Last year, at this time I had written an article A Year Older and 3 SQL Server Books and 3 Video Courses – 33. I had written a total of 3 books by that time and had published total of  3 Pluralsight courses. When I look back the year, I feel that I gave my best to last year. Sine Last July 30th, I have written 6 more books and 5 more video courses. The total is now 9 books and 8 video courses. It seems that I have been producing one new book or course every month since last July. Building a High Traffic, Profitable Blog Out of my 8 courses my favorite course is my latest course at Pluralsight. This course is about how to build a high traffic blog and monetize it. I have been blogging for over 7 years and there have been many hurdles and roadblocks but I have never stopped blogging any single day. There have been many instances when I felt I should just hit delete and remove my entire blog from the web but fortunately I had courage to stand by on my decisions. Well at the end, I kept on fighting through the difficult time and kept on blogging. Every day there was a lesson to learn and every day there was an issue to resolve. I never gave up and kept on building new content. Today after 7 years, when I look back there are many stories to tell. It was impossible to write down the stories so I decided to build a course based on my experience. In this course, I share all the best tricks to build a high traffic, profitable blog. When we talk about profit, people often talk about money but the reality is that profit is much bigger word than money. There are many different ways one can profit from their own blog. In this course, I discuss about all different ways about how you can be profitable by building a high traffic blog. I believe this course is for everybody who aspire to build a website or blog which gives them a profit.  Here are the major topics based out of this course. Introduction Techniques to Engage Blog Readers Social Media – Social Sharing and Social Networking Search Engine Optimization (SEO) Monetizing a Blog Frequently Asked Questions Checklists Personally I believe this is the best gift I can give to all of you my friends. Build a successful high traffic blog and monetize it. Here is the list of the all of my video courses and here is the list of all of the books. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: About Me, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: Blogging

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  • High load on a nagios server -- How many service checks for a nagios server is too many?

    - by Josh
    I have a nagios server running Ubuntu with a 2.0 GHz Intel Processor, a RAID10 array, and 400 MB of RAM. It monitors a total of 42 services across 8 hosts, most of which are checked using the check_http plugin even 5 minutes, some every minute. Recently the load on the nagios server has been above 4, often as high as 6. The server also runs cacti, gathering statistics every minute for 6 hosts. I wonder, how many services should hardware like this be able to handle? Is the load so high because I am pushing the limits of the hardware, or should this hardware be able to handle 42 service checks plus cacti? If the hardware is inadequate, should I look to add more RAM, more cores, or faster cores? What hardware / service checks are others running?

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  • The Legend of Zelda – 1980s High School Style [Video]

    - by Asian Angel
    What happens when you mix the Legend of Zelda with the 80s high school scene? Something fun and cheesy that makes you wish there really was a movie based on this! From YouTube: In this charming critically-acclaimed tale of first love, Link, an eternal optimist and adventurer, seeks to capture the heart of Zelda, an unattainable high school beauty and straight-A student. He surprises just about everyone-including himself-when she returns the sentiment. But the high school’s over-possessive, megalomaniacal Principal Ganondorf doesn’t approve and it’s going to take more than just the power of love to conquer all. The Legend of Zelda (1987) Trailer [via Geeks are Sexy] Latest Features How-To Geek ETC How To Remove People and Objects From Photographs In Photoshop Ask How-To Geek: How Can I Monitor My Bandwidth Usage? Internet Explorer 9 RC Now Available: Here’s the Most Interesting New Stuff Here’s a Super Simple Trick to Defeating Fake Anti-Virus Malware How to Change the Default Application for Android Tasks Stop Believing TV’s Lies: The Real Truth About "Enhancing" Images The Legend of Zelda – 1980s High School Style [Video] Suspended Sentence is a Free Cross-Platform Point and Click Game Build a Batman-Style Hidden Bust Switch Make Your Clock Creates a Custom Clock for your Android Homescreen Download the Anime Angels Theme for Windows 7 CyanogenMod Updates; Rolls out Android 2.3 to the Less Fortunate

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  • How to start a high school Java/Android development club for 13-17 year olds

    - by PaulHurleyuk
    My wife is a high school maths teacher, and is considering starting a programming club for 13-17 years olds who show an interest. Their interest seems to be around Apps and Android which I have little experience of. The kids would be (presumably) interested in programming, and have a fairly high level of computing knowledge. We would provide them with resources and some knowledge, but hopefully a lot would be self guided. I'm hoping stack overflow'ers can provide some tips or starting points. Specific things I think I'll need are; A development Environment; Currently I'm looking towards Java and Android, developed in Eclipse, probably installed on donated older hardware Some initial direction; There seem to be a plethora or 'start android' tutorials, so some recommendations for good ones are valuable, as are recommended paper books A Target; Some final project they should be shooting for A Route; This is where I'm most stuck, how to lead them through the required Java concepts and learning they would need Some related questions already out there Language+IDE for teaching high school students? Teaching "web design/development" to high-school home-school group. Good sources? How can I bootstrap a software development community at my school?

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  • Welcome to Gotham High [Video]

    - by Asian Angel
    Goodbye Metropolis, hello insane asylum. That is the state of life for young Harley Quinn now that she has moved to Gotham. With only two high schools to choose between, her parents have decided to send her to Gotham High where life is anything but dull! Note: Video contains some language that may be considered inappropriate. Gotham High (2013) Dark Knight Batman PARODY! [via Neatorama] Why Does 64-Bit Windows Need a Separate “Program Files (x86)” Folder? Why Your Android Phone Isn’t Getting Operating System Updates and What You Can Do About It How To Delete, Move, or Rename Locked Files in Windows

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  • High Jinks, Hi Jacks, Exceptional DBA Awards and PASS

    - by Rodney
    The countdown to PASS has counted down.  The day after tomorrow I will board a plane, like many others, on my way for the 4th year in a row to SQL PASS Summit.  The anticipation has been excruciating but luckily I have this little thing called a day job as a DBA that has kept me busy and not thinking too much about the event. Well that is not exactly true since my beautiful wife works for PASS so we get to talk about SQL from the time we wake up until late in the evening. I would not have it any other way and I feel very fortunate to be a part of this great event and to have been chosen as the Exceptional DBA Award judge also for the 4th year in a row.  This year, I will have been again tasked with presenting the award to the winner, Mr. Jeff Moden and it will be a true honor to meet him in person as I have read many of his articles on SSC and have attended his session at PASS previously.  The speech is all ready but one item remains, which will be a surprise to all who attend the party on Tuesday night in Seattle (see links below).  Let's face it, Exceptional DBAs everywhere work very hard protecting our data stores, tuning queries, mentoring, saving money, installing clusters, etc and once in a while there is time to be exceptionally non-professional and have a bit of fun. Once incident that happened this year that falls under the High Jinks category was when my network admin asked if I could Telnet into a SQL instance and see if I could make the connection through the firewall that he had just configured. I was able to establish a connection on port 1433 and it occurred to me that it would be very interesting if I could actually run T-SQL queries via a Telnet session much like you might do with an SMTP server. With that thought, I proceeded to demonstrate this could be possible by convincing my senior DBA Shawn McGehee that I was able to do so. At first he did not believe me. It shook his world view.  It was inconceivable.  What I had done, behind the scenes, of course, was to copy and rename SQLCMD.exe to Telnet.exe and used it to connect and run a simple, "Select * from sys.databases" on the SQL instance. I think if it had been anyone other than Shawn I could have extended this ruse indefinitely but he caught on within 30 seconds. It was a fun thirty seconds though. On the High Jacks side of the house, which is really merged to be SQL HACKS, I finally, after several years of struggling with how to connect to an untrusted domain like in a DMZ with a windows account in SSMS, I stumbled upon a solution that does away with the requirement to use SQL Authentication.  While "Runas" is a great command to use to run an application with a higher privileged account, I had not previously been able to figure out how to connect to the remote domain with SSMS and "Runsas". It never connected and caused a login failure every time for the remote windows domain account. Then I ran across an option for "Runas",   "/netonly".  This option postpones the login until a connection is made and only then passes the remote login you supply when you first launch SSMS with the "Runas" command. So a typical shortcut would look like: "C:\Windows\System32\runas.exe /netonly /user:remotedomain.com\rodlandrum "C:\Program Files\Microsoft SQL Server\100\Tools\Binn\VSShell\Common7\IDE\Ssms.exe" You will want to make sure the passwords are synced between the two domains, your local domain and the remote domain, otherwise you may have account lockout issues, but I have found in weeks of testing this is a stable solution. Now it is time to get ready to head for Seattle. Please, if you see me (@SQLBeat) or my wife (@Karlakay22) please run up and high five me (wait..High Jinks.High Jacks.High Fives.Need to change the title) or give me a big bear hug if you are strong enough to lift me off the ground. And if you do actually do that, I will think you are awesome and will not embarrass you by crying out for help or complaining of a broken back or sciatic nerve damage. And now the links to others who have all of the details. First, for the MVP Deep Dives 2, of which, like John, I was lucky enough to be able to participate in this year. http://www.simple-talk.com/community/blogs/johnm/archive/2011/09/29/103577.aspx And the details of the SSC party where the Exceptional DBA of 2011, Jeff Moden, will be awarded. http://www.simple-talk.com/community/blogs/rebecca_amos/archive/2011/10/05/103661.aspx   Cheers! Rodney

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  • Is the SAN dying???

    - by RickHeiges
    Is the SAN dying? The reason that I ask this question is that MSFT has unleashed technologies this year that point in that direction Always ON Availability Groups shuns shared storage Windows 2012 has Storage Replication Technology that does not require a SAN Windows 2012 has Hyper-V Replica Technology that does not require a SAN PDW v2 continues to reinforce the approach to avoid shared storage I'm not saying that SAN technology does not have its place or does not have benefits inherent to the beast....(read more)

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  • High Speed Photographs Capture Pellet Gun Destruction

    - by Jason Fitzpatrick
    What do you get when you combine high speed flash photography, a carefully focused camera, and pellet gun? Gloriously detailed pictures of pellets tearing apart fruit, cans, ceramic gnomes, and more. Alan Sailer has a passion; in his garage studio he photographs all manner of objects–bottles, raspberries, candy, soda cans–at the moment a pellet shot from a pellet gun tears them apart. The results are beautiful and reminescent of early high-speed photos by photography pioneer Edgerton Born. Hit up the link below to check out the collection and read more about his process. Alan Sailer’s High Speed Photographs [via FlavorWire] Make Your Own Windows 8 Start Button with Zero Memory Usage Reader Request: How To Repair Blurry Photos HTG Explains: What Can You Find in an Email Header?

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  • What is the meaning of 'high cohesion'?

    - by Max
    I am a student who recently joined a software development company as an intern. Back at the university, one of my professors used to say that we have to strive to achieve "Low coupling and high cohesion". I understand the meaning of low coupling. It means to keep the code of separate components separately, so that a change in one place does not break the code in another. But what is meant by high cohesion. If it means integrating the various pieces of the same component well with each other, I dont understand how that becomes advantageous. What is meant by high cohesion? Can an example be explained to understand its benefits?

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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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  • It is Wise to Buy High PR Backlinks

    With competition extending into the virtual world, it is necessary to make sure that websites are linked to other websites of high PageRank. This is vital because, it could enjoy the airs of being on the top by mere association with another credible website. The internet domain is now extended and offers scope for websites of high quality to be on the top forever

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  • C++ Programming: Better Accessibility with High DPI Support and MFC 10

    A number of factors are driving the requirement for applications to correctly support high DPI settings--increased monitor resolutions are making it more difficult for users to read text on the screen, compliance with disability access legislation is an increasingly important factor for corporations, and users are now expecting applications to behave well at higher DPI settings. MFC 10 and Visual C++ 2010 have built-in support for high DPI, making the development of a DPI-aware application quicker and more simple.

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  • Research topics for starting and optimizing a high-traffic website

    - by user745434
    I bury a good deal of my ideas for fear that I don't know enough about scaling web applications and high-traffic websites. That said, I'd like to know of any general topics to research in order to ensure that your web app doesn't break / slow down when you start getting to Twitter-level traffic. I'm looking for research topics with, preferably, additional resources. For example: Make sure you optimize SQL queries (see High Performance MySQL Optimization)

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  • 5 Easy Ways to Get High PR Links to Boost Your Site in Google

    High PR links are some of the most valuable aspects in any link-building & SEO campaign. Not only do these links make Google respect your site more, but they can also boost your site's ranking overnight. Here are 5 places to get high quality links that will do a lot of good to your site's ranking in Google.

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  • Oracle Data Integration 12c: Simplified, Future-Ready, High-Performance Solutions

    - by Thanos Terentes Printzios
    In today’s data-driven business environment, organizations need to cost-effectively manage the ever-growing streams of information originating both inside and outside the firewall and address emerging deployment styles like cloud, big data analytics, and real-time replication. Oracle Data Integration delivers pervasive and continuous access to timely and trusted data across heterogeneous systems. Oracle is enhancing its data integration offering announcing the general availability of 12c release for the key data integration products: Oracle Data Integrator 12c and Oracle GoldenGate 12c, delivering Simplified and High-Performance Solutions for Cloud, Big Data Analytics, and Real-Time Replication. The new release delivers extreme performance, increase IT productivity, and simplify deployment, while helping IT organizations to keep pace with new data-oriented technology trends including cloud computing, big data analytics, real-time business intelligence. With the 12c release Oracle becomes the new leader in the data integration and replication technologies as no other vendor offers such a complete set of data integration capabilities for pervasive, continuous access to trusted data across Oracle platforms as well as third-party systems and applications. Oracle Data Integration 12c release addresses data-driven organizations’ critical and evolving data integration requirements under 3 key themes: Future-Ready Solutions : Supporting Current and Emerging Initiatives Extreme Performance : Even higher performance than ever before Fast Time-to-Value : Higher IT Productivity and Simplified Solutions  With the new capabilities in Oracle Data Integrator 12c, customers can benefit from: Superior developer productivity, ease of use, and rapid time-to-market with the new flow-based mapping model, reusable mappings, and step-by-step debugger. Increased performance when executing data integration processes due to improved parallelism. Improved productivity and monitoring via tighter integration with Oracle GoldenGate 12c and Oracle Enterprise Manager 12c. Improved interoperability with Oracle Warehouse Builder which enables faster and easier migration to Oracle Data Integrator’s strategic data integration offering. Faster implementation of business analytics through Oracle Data Integrator pre-integrated with Oracle BI Applications’ latest release. Oracle Data Integrator also integrates simply and easily with Oracle Business Analytics tools, including OBI-EE and Oracle Hyperion. Support for loading and transforming big and fast data, enabled by integration with big data technologies: Hadoop, Hive, HDFS, and Oracle Big Data Appliance. Only Oracle GoldenGate provides the best-of-breed real-time replication of data in heterogeneous data environments. With the new capabilities in Oracle GoldenGate 12c, customers can benefit from: Simplified setup and management of Oracle GoldenGate 12c when using multiple database delivery processes via a new Coordinated Delivery feature for non-Oracle databases. Expanded heterogeneity through added support for the latest versions of major databases such as Sybase ASE v 15.7, MySQL NDB Clusters 7.2, and MySQL 5.6., as well as integration with Oracle Coherence. Enhanced high availability and data protection via integration with Oracle Data Guard and Fast-Start Failover integration. Enhanced security for credentials and encryption keys using Oracle Wallet. Real-time replication for databases hosted on public cloud environments supported by third-party clouds. Tight integration between Oracle Data Integrator 12c and Oracle GoldenGate 12c and other Oracle technologies, such as Oracle Database 12c and Oracle Applications, provides a number of benefits for organizations: Tight integration between Oracle Data Integrator 12c and Oracle GoldenGate 12c enables developers to leverage Oracle GoldenGate’s low overhead, real-time change data capture completely within the Oracle Data Integrator Studio without additional training. Integration with Oracle Database 12c provides a strong foundation for seamless private cloud deployments. Delivers real-time data for reporting, zero downtime migration, and improved performance and availability for Oracle Applications, such as Oracle E-Business Suite and ATG Web Commerce . Oracle’s data integration offering is optimized for Oracle Engineered Systems and is an integral part of Oracle’s fast data, real-time analytics strategy on Oracle Exadata Database Machine and Oracle Exalytics In-Memory Machine. Oracle Data Integrator 12c and Oracle GoldenGate 12c differentiate the new offering on data integration with these many new features. This is just a quick glimpse into Oracle Data Integrator 12c and Oracle GoldenGate 12c. Find out much more about the new release in the video webcast "Introducing 12c for Oracle Data Integration", where customer and partner speakers, including SolarWorld, BT, Rittman Mead will join us in launching the new release. Resource Kits Meet Oracle Data Integration 12c  Discover what's new with Oracle Goldengate 12c  Oracle EMEA DIS (Data Integration Solutions) Partner Community is available for all your questions, while additional partner focused webcasts will be made available through our blog here, so stay connected. For any questions please contact us at partner.imc-AT-beehiveonline.oracle-DOT-com Stay Connected Oracle Newsletters

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  • Nagios Availability Report plotting in Graphite

    - by Roman Zenka
    I would like to plot my Nagios availability reports over time. Does anyone know a plugin that would do so? I found 'graphios' at https://github.com/shawn-sterling/graphios that would plot extra data provided by plugins. What I need instead is a plugin that would plot information such as: 'the service was in ERROR state 0.5% of the time last week, while the week before it was 1%'. This would be useful for knowing whether the overall stability is getting better.

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  • Rendering large and high poly meshes

    - by Aurus
    Consider an huge terrain that has a lot polygons, to render this terrain I thought of following techniques: Using height-map instead of raw meshes: Yes, but I want to create a lot of caves and stuff that simply wont work with height-maps. Using voxels: Yes, but I think that this would be to much since I don't even want to support changing terrain.. Split into multiple chunks and do some sort of LOD with the mesh: Yes, but how would I do that? Tessellation usually creates more detail not less. Precompute the same mesh in lower poly version (like Mudbox does) and depending on the distance it renders one of these meshes: Graphic memory is limited and uploading only the chunks won't solve that problem since the traffic would be too high. IMO the last one sounds really good, but imagine the following process: Upload and render the chunks depending on the current player position. [No problem] Player will walk straight forward Now we maybe have to change on of the low poly chunk with the high poly one So, Remove the low poly chunk and load the high poly chunk [Already to much traffic here, I think] I am not very experienced in graphic programming and maybe the upper process is totally okay but somehow I think it is too much. And how about the disk space it would require.. I think 3 kind of levels would be fine but isn't that also too much? (I am using OpenGL but I don't think that this is important)

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  • Should mock objects for tests be created at a high or low level

    - by Danack
    When creating unit tests for those other objects, what is the best way to create mock objects that provide data to other objects. Should they be created at a 'high level' and intercept the calls as soon as possible, or should they be done at a 'low level' and so make as much as the real code still be called? e.g. I'm writing a test for some code that requires a NoteMapper object that allows Notes to be loaded from the DB. class NoteMapper { function getNote($sqlQueryFactory, $noteID) { // Create an SQL query from $sqlQueryFactory // Run that SQL // if null // return null // else // return new Note($dataFromSQLQuery) } } I could either mock this object at a high level by creating a mock NoteMapper object, so that there are no calls to the SQL at all e.g. class MockNoteMapper { function getNote($sqlQueryFactory, $noteID) { //$mockData = {'Test Note title', "Test note text" } // return new Note($mockData); } } Or I could do it at a very low level, by creating a MockSQLQueryFactory that instead of actually querying the database just provides mock data back, and passing that to the current NoteMapper object. It seems that creating mocks at a high level would be easier in the short term, but that in the long term doing it at a low level would be more powerful and possibly allow more automation of tests e.g. by recording data in an out of a DB and then replaying that data for tests. Is there a recommended way of creating mocks? Are there any hard and fast rules about which are better, or should they both be used where appropriate?

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  • Calculate open timeslots given availability and existing appointments - by day

    - by Andre
    Overview: I have a table which stores a persons "availability" for a current day, e.g. Mon - 8:00am - 11:30am Mon - 1:30pm - 6:00pm A second table stores appointments that this person already has for the same day, e.g. Mon - 8:30am - 11:00am Mon - 2:30pm - 4pm Desired result: Doing calculationsI'd like to have the following result - e.g. "this person has availability on the given day": Mon - 8:00am - 8:30am Mon - 11:00am - 11:30am Mon - 1:30pm - 2:30pm Mon - 4:00pm - 6:00pm Any ideas on how to calculate the output given the two inputs (e.g. availability, existing appointments) would be greatly appreciated. Preferably I'd use javascript on the client to do the calculating as I would believe that doing it within the DB (I'm using MSSQL) would be slow for many records, persons, etc. Hope this is enough information to illustrate the problem at hand - Many thanks in advance.

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  • Exchange 2010 DAG + VMWare HA = no support?

    - by Dan
    We currently have an Exchange 2003 clustered environment (two machine cluster) that we're looking to upgrade to 2010. We recently purchased a VMWare virtualization environment (three Dell R710's with an EMC NS-120 serving up NFS datastores - iSCSI is available) that we wish to use for this new environment. I'm seeing that Microsoft does not support Exchange 2010 DAGs with a virtualization high availability solution (see links below). I would like to utilize the DAG to ensure the data stays available if one host goes down, and HA to ensure that if the physical host goes down, the VM will come back up on the other available host. Does anybody know why MS does not support this? VMWare HA will only restart the VM if it is hung/down - I don't see any difference between this and restarting the physical box if someone pulled the power... Will we only run into issues with support if it has something to do with HA/DAG failover or will they see we have HA and tell us to put it on a physical box even if it has nothing to do with HA? If we disable HA for these VM's will that satisfy them on a support case? Has anybody set up an Exchange 2010 DAG on VMware with HA enabled? Will they have any issues with using an NFS datastore? We have much greater flexibility on the EMC with NFS vs iSCSI, so I would prefer to continue utilizing that. Thanks for any input! http://www.vmwareinfo.com/2010/01/verifying-microsoft-exchange-2010.html Take a look at the second image under "Not Supported" http://technet.microsoft.com/en-us/library/aa996719.aspx "Microsoft doesn't support combining Exchange high availability solutions (database availability groups (DAGs)) with hypervisor-based clustering, high availability, or migration solutions. DAGs are supported in hardware virtualization environments provided that the virtualization environment doesn't employ clustered root servers."

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  • High availability virtual machines

    - by Jeremy
    I've been reading a lot about high availability virtualization, either via Hyper-V or VMWare. In that context, essentially high availabliity means that the VM is hosted by a closter of physical servers (nodes), so if one of the physical servers goes down, the VM can still be served by other physical servers. So far so good, the physical cluster and the VM itself are highly available. However if the service being provided, let's say SQL server, MSDTC, or any other service, are actually being provided by the VM image and the virtualized operating system. So I imagine that there is still a point of failure at the virtual layer that isn't accounted for. Something could happen within the virtual machine itself that the physican cluster can not account for, correct? In that instance the physican failover cluster (Hyper-V) or VMWare host, can not fail over, because the issue is not with one of the servers in the physical cluster - failing over a physical node would not do any good. Does this necessitate building a virtual failover cluster on top of the physical one, or is this not necessary? Alternatively, I suppose you could skip the phsyical clustering, and just cluster at the virtual layer (Child based failover clustering), because that should still survive a physical failure. See image below showing parent based (left), child based (right) and a combination (center). Is parent based as far as you need to go, or is child based more appropriate?

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  • Oracle Coherence 3.5 : Create Internet-scale applications using Oracle's high-performance data grid

    - by frederic.michiara
    Oracle Coherence Coherence provides replicated and distributed (partitioned) data management and caching services on top of a reliable, highly scalable peer-to-peer clustering protocol. Coherence has no single points of failure; it automatically and transparently fails over and redistributes its clustered data management services when a server becomes inoperative or is disconnected from the network. When a new server is added, or when a failed server is restarted, it automatically joins the cluster and Coherence fails back services to it, transparently redistributing the cluster load. Coherence includes network-level fault tolerance features and transparent soft re-start capability to enable servers to self-heal. For the ones looking at an easy reading and first good approach to Oracle Coherence, I would recommend reading the following book : Overview of Oracle Coherence 3.5 Build scalable web sites and Enterprise applications using a market-leading data grid product Design and implement your domain objects to work most effectively with Coherence and apply Domain Driven Designs (DDD) to Coherence applications Leverage Coherence events and continuous queries to provide real-time updates to client applications Successfully integrate various persistence technologies, such as JDBC, Hibernate, or TopLink, with Coherence Filled with numerous examples that provide best practice guidance, and a number of classes you can readily reuse within your own applications This book is targeted to Architects and developers, and as in our team we're more about Solutions Architects than developers I found interest in this book as it help to understand better Oracle Coherence and its value. The only point I may not agree with the authors is that Oracle Coherence is not an alternative to Oracle RAC in providing High Availability, but combining both Oracle RAC and Oracle Coherence will help Architects and Customers to reach higher level of service and high-availability. This book is available on https://www.packtpub.com/oracle-coherence-3-5/book Need to find out about Table of contents : https://www.packtpub.com/toc/oracle-coherence-35-table-contents Discover a sample chapter : https://www.packtpub.com/sites/default/files/6125_Oracle%20Coherence_SampleChapter.pdf Read also articles from the Authors on http://www.packtpub.com/ : Working with Aggregators in Oracle Coherence 3.5 Working with Value Extractors and Simplifying Queries in Oracle Coherence 3.5 Querying the Data Grid in Coherence 3.5: Obtaining Query Results and Using Indexes Installing Coherence 3.5 and Accessing the Data Grid: Part 1 Installing Coherence 3.5 and Accessing the Data Grid: Part 2 For more information on Oracle Coherence : What Oracle Coherence Can Do for You... : http://www.oracle.com/technology/products/coherence/coherencedatagrid/coherence_solutions.html Oracle Coherence on OTN : http://www.oracle.com/technology/products/coherence/index.html Oracle Coherence Knowledge Base : http://coherence.oracle.com/display/COH/Oracle+Coherence+Knowledge+Base+Home

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  • Load balancing Apache on a budget?

    - by Industrial
    Hi everyone, I am trying to get my head around the concept of load balancing to ensure availability and redundancy to keep users happy when things go wrong, rather than load balancing for the sake of offering blistering speed to millions of users. We're on a budget and trying to stick to the stuff where there's plenty of knowledge available, so running Apache on Ubuntu VPS's seems like the strategy until some famous search engine acquire us (Saturday irony included, please note). At least to me, it's a complete jungle of different solutions available. Apaches own mod_proxy & HAproxy are two that we found by a quick google search, but having zero experience of load balancing, I have no idea of what would be appropriate for our situation, or what we would look after while choosing a solution to solve our availability concerns. What is the best option for us? What should we do to get availability high whilst staying inside our budgets?

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  • High CPU load - Ubuntu 14.04

    - by watt
    I noticed that sometimes when browsing (with other processes in the background), I get very high CPU load for the browser process (over 100%) and the computer becomes really slow. I tried switching from Firefox (with just a few extensions) to Chromium, but same thing happens without me visiting graphics-intense sites, flash sites or anything like that. I also noticed python or node (when running "make") produce the same high CPU load from time to time so this is not necessarily browser-related. When I only have a browser open, it doesn't seem to happen and everything is fine in Windows 7. I switched from unity to gnome3 with no effect. Specs: lenovo w510 (4gb RAM, i7 q820 @ 1.73) + up to date Ubuntu 14.04 64bit. Printscreen: http://imgur.com/8MZJNKC Do you guys have any idea why this might happen? Please let me know if there's other info you need. Thanks!

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