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• HDMI sound gone, can't figure out how to turn it back on

  - by Oli

  I have had an Acer Revo box as a media centre for a while. I recently installed Ubuntu Server (10.10) on it and polished it up with nodm (one of the most simple ways to launch an X session) and installed boxee. It's been working fine for over a month. It's just running ALSA. I've had problems with PulseAudio/Boxee/HDMI before so I wanted to keep it simple. And that worked. It pushed both PCM and digital (AAC and various Dolby codecs) over HDMI perfectly. But I restarted it the other day after mucking around with some nfs configuration and now there isn't any sound. The hardware is an ION chipset. Nvidia 9400M graphics with Nvidia MCP79/7A audio. One thing I have noticed is there doesn't appear to be any sign of a IEC958 device. A traditional fix in the past for fresh installs has been to load alsamixer, find the IEC device and toggle its mute but I can't. I'm certain this used to represent the HDMI output. It just doesn't seem to exist any more unless I run sudo alsa-utils restart while boxee is running, when I see it in an error message: * Shutting down ALSA... [ OK ] * Setting up ALSA... * warning: 'alsactl restore' failed with error message 'alsactl: set_control:1388: Cannot write control '2:0:0:IEC958 Playback Default:0' : Operation not permitted'... ...done. When nodm (and thus boxee) aren't running, I don't see this error but alsamixer still doesn't show the IEC channel. aplay -l gives: card 0: NVidia [HDA NVidia], device 0: ALC662 rev1 Analog [ALC662 rev1 Analog] Subdevices: 1/1 Subdevice #0: subdevice #0 card 0: NVidia [HDA NVidia], device 3: HDMI 0 [HDMI 0] Subdevices: 0/1 Subdevice #0: subdevice #0 Its section in lshw reads: *-multimedia description: Audio device product: MCP79 High Definition Audio vendor: nVidia Corporation physical id: 8 bus info: pci@0000:00:08.0 version: b1 width: 32 bits clock: 66MHz capabilities: pm bus_master cap_list configuration: driver=HDA Intel latency=0 maxlatency=5 mingnt=2 resources: irq:22 memory:fae78000-fae7bfff I was running on the stock PAE kernel but now it's running on 2.6.37.1. I upgraded to see if that fixed things; it didn't. I'm considering a reinstall but I hate doing that because a) there's a bit of custom configuration in getting X and Boxee to start on boot and b) I don't know what the problem is. If I reinstall this time, I'll end up doing that every time the sound breaks. I love Ubuntu but I don't want to install it once a month. Is there any way to forcibly reset all alsa settings and restart from scratch (without doing a reinstall)? Any other tips? If you need more information, just ask.

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• Google I/O 2012 - New Low-Level Media APIs in Android

  Google I/O 2012 - New Low-Level Media APIs in Android Dave Burke Jellybean introduces a new set of powerful low-level media APIs that provide developers with the ability to access hardware codecs directly from Java. This session introduces the new APIs with examples. For all I/O 2012 sessions, go to developers.google.com From: GoogleDevelopers Views: 0 0 ratings Time: 01:05:50 More in Science & Technology

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• Database Security: The First Step in Pre-Emptive Data Leak Prevention

  - by roxana.bradescu

  With WikiLeaks raising awareness around information leaks and the harm they can cause, many organization are taking stock of their own information leak protection (ILP) strategies in 2011. A report by IDC on data leak prevention stated: Increasing database security is one of the most efficient and cost-effective measures an organization can take to prevent data leaks. By utilizing the data protection, access control, account management, encryption, log management, and other security controls inherent in the database management system, entities can institute first-level control over the widest range of protected information. As a central repository for unstructured data, which is growing at leaps and bounds, the database should be the first layer providing information leakage protection. Unfortunately, most organizations are not taking sufficient steps to protect their databases according to a survey of the Independent Oracle User Group. For example, any operating system administrator or database administrator can access the all the data stored in the database in most organizations. Without any kind of auditing or monitoring. And it's not just administrators, database users can typically access the database with ad-hoc query tools from their desktop and by-pass any application level controls. Despite numerous regulations calling for controls to limit the powers of insiders, most organizations still put too many privileges in the hands of their employees. Time and time again these excess privileges have backfired. Internal agents were implicated in almost half of data breaches according to the Verizon Data Breach Investigations Report and the rate is rising. Hackers also took advantage of these excess privileges very successfully using stolen credentials and SQL injection attacks. But back to the insiders. Who are these insiders and why do they do it? In 2002, the U.S. Secret Service (USSS) behavioral psychologists and CERT information security experts formed the Insider Threat Study team to examine insider threat cases that occurred in US critical infrastructure sectors, and examined them from both a technical and a behavioral perspective. A series of fascinating reports has been published as a result of this work. You can learn more by watching the ISSA Insider Threat Web Conference. So as your organization starts to look at data leak prevention over the coming year, start off by protecting your data at the source - your databases. IDC went on to say: Any enterprise looking to improve its competitiveness, regulatory compliance, and overall data security should consider Oracle's offerings, not only because of their database management capabilities but also because they provide tools that are the first layer of information leak prevention. Learn more about Oracle Database Security solutions and get the whitepapers, demos, tutorials, and more that you need to protect data privacy from internal and external threats.

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• Google I/O 2012 - Playing with Patterns

  Google I/O 2012 - Playing with Patterns "Marco Paglia Best-in-class application designers and developers will talk about their experience in developing for Android, showing screenshots from their app, exploring the challenges they faced, and offering creative solutions congruent with the Android Design guide. Guests will be invited to show examples of visual and interaction patterns in their application that manage to keep it simultaneously consistent and personal. For all I/O 2012 sessions, go to developers.google.com From: GoogleDevelopers Views: 1 0 ratings Time: 02:13:20 More in Science & Technology

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• Which is preferable? To know jQuery well, or to know JavaScript well? [closed]

  - by Marwan

  I'm quite familiar with using jQuery, but I've come to feel like a bit of a dummy using it, as my knowledge of JavaScript itself is rather poor. So I'm considering abandoning jQuery and spending time working in straight JS... perhaps even creating my own framework as a learning experience. Does this make sense though? Is there any real point to obtaining more than a passing knowledge of JavaScript when jQuery allows me to accomplish so much, so quickly?

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• Schema Based Code Completion for NetBeans Platform Applications

  - by Geertjan

  Toni's recent blog entry provides, among several other interesting things, instructions for something I've been wanting to cover for a long time, which is schema based code completion: The above is a sample I created via Toni's tutorial, using the schema described here: http://www.w3schools.com/schema/schema_example.asp The support for the Navigator ain't bad either, especially considering I didn't do any coding at all to get all this: And here's where you can find the whole sample: http://java.net/projects/nb-api-samples/sources/api-samples/show/versions/7.2/misc/ShipOrder

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• Why is multithreading often preferred for improving performance?

  - by user1849534

  I have a question, it's about why programmers seems to love concurrency and multi-threaded programs in general. I'm considering 2 main approaches here: an async approach basically based on signals, or just an async approach as called by many papers and languages like the new C# 5.0 for example, and a "companion thread" that manages the policy of your pipeline a concurrent approach or multi-threading approach I will just say that I'm thinking about the hardware here and the worst case scenario, and I have tested this 2 paradigms myself, the async paradigm is a winner at the point that I don't get why people 90% of the time talk about multi-threading when they want to speed up things or make a good use of their resources. I have tested multi-threaded programs and async program on an old machine with an Intel quad-core that doesn't offer a memory controller inside the CPU, the memory is managed entirely by the motherboard, well in this case performances are horrible with a multi-threaded application, even a relatively low number of threads like 3-4-5 can be a problem, the application is unresponsive and is just slow and unpleasant. A good async approach is, on the other hand, probably not faster but it's not worst either, my application just waits for the result and doesn't hangs, it's responsive and there is a much better scaling going on. I have also discovered that a context change in the threading world it's not that cheap in real world scenario, it's in fact quite expensive especially when you have more than 2 threads that need to cycle and swap among each other to be computed. On modern CPUs the situation it's not really that different, the memory controller it's integrated but my point is that an x86 CPUs is basically a serial machine and the memory controller works the same way as with the old machine with an external memory controller on the motherboard. The context switch is still a relevant cost in my application and the fact that the memory controller it's integrated or that the newer CPU have more than 2 core it's not bargain for me. For what i have experienced the concurrent approach is good in theory but not that good in practice, with the memory model imposed by the hardware, it's hard to make a good use of this paradigm, also it introduces a lot of issues ranging from the use of my data structures to the join of multiple threads. Also both paradigms do not offer any security abut when the task or the job will be done in a certain point in time, making them really similar from a functional point of view. According to the X86 memory model, why the majority of people suggest to use concurrency with C++ and not just an async approach ? Also why not considering the worst case scenario of a computer where the context switch is probably more expensive than the computation itself ?

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• Oracle University New Courses (Week 14)

  - by swalker

  Oracle University released the following new (versions of) courses recently: Database Oracle Data Modeling and Relational Database Design (4 days) Fusion Middleware Oracle Directory Services 11g: Administration (5 days) Oracle Unified Directory 11g: Services Deployment Essentials (2 days) Oracle GoldenGate 11g Management Pack: Overview (1 day) Business Intelligence & Datawarehousing Oracle Database 11g: Data Mining Techniques (2 days) Oracle Solaris Oracle Solaris 10 System Administration for HP-UX Administrators (5 days) E-Business Suite R12.x Oracle Time and Labor Fundamentals Get in contact with your local Oracle University team for more details and course dates. Stay Connected to Oracle University: LinkedIn OracleMix Twitter Facebook Google+

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• Design Patterns for Coordinating Change Event Listeners

  - by mkraken

  I've been working with the Observer pattern in JavaScript using various popular libraries for a number of years (YUI & jQuery). It's often that I need to observe a set of property value changes (e.g. respond only when 2 or more specific values change). Is there a elegant way to 'subscribe' the handler so that it is only called one time? Is there something I'm missing or doing wrong in my design?

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• Oracle GoldenGate: Knowledge Document Series Post #2

  - by Doug Reid

  0 false 18 pt 18 pt 0 0 false false false /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;} 0 false 18 pt 18 pt 0 0 false false false /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;} For our second post in this series the team would like to highlight the knowledge document “How-To: Oracle GoldenGate – Heartbeat Process to Monitor Lag and Performance”. This knowledge document outlines a procedure to reliably measure lag between source and target systems through the use of 'heartbeat' tables. The basic idea is to have a table on the source system that gets updated at a predetermined interval. In your capture processes you would capture the update from the heartbeat table. Using tokens you would add some additional information to the heartbeat record to be able to tell which extract process was capturing the update. This additional information would be used downstream to calculate the real lag time between the source and target systems for a given extract and by checking the last update time on the heartbeat at the target you could also determine if data has stopped flowing between the source and target.  Click here to view the document

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• BI Applications overview

  - by sv744

  Welcome to Oracle BI applications blog! This blog will talk about various features, general roadmap, description of functionality and implementation steps related to Oracle BI applications. In the first post we start with an overview of the BI apps and will delve deeper into some of the topics below in the upcoming weeks and months. If there are other topics you would like us to talk about, pl feel free to provide feedback on that. The Oracle BI applications are a set of pre-built applications that enable pervasive BI by providing role-based insight for each functional area, including sales, service, marketing, contact center, finance, supplier/supply chain, HR/workforce, and executive management. For example, Sales Analytics includes role-based applications for sales executives, sales management, as well as front-line sales reps, each of whom have different needs. The applications integrate and transform data from a range of enterprise sources—including Siebel, Oracle, PeopleSoft, SAP, and others—into actionable intelligence for each business function and user role. This blog  starts with the key benefits and characteristics of Oracle BI applications. In a series of subsequent blogs, each of these points will be explained in detail. Why BI apps? Demonstrate the value of BI to a business user, show reports / dashboards / model that can answer their business questions as part of the sales cycle. Demonstrate technical feasibility of BI project and significantly lower risk and improve success Build Vs Buy benefit Don’t have to start with a blank sheet of paper. Help consolidate disparate systems Data integration in M&A situations Insulate BI consumers from changes in the OLTP Present OLTP data and highlight issues of poor data / missing data – and improve data quality and accuracy Prebuilt Integrations BI apps support prebuilt integrations against leading ERP sources: Fusion Applications, E- Business Suite, Peoplesoft, JD Edwards, Siebel, SAP Co-developed with inputs from functional experts in BI and Applications teams. Out of the box dimensional model to source model mappings Multi source and Multi Instance support Rich Data Model    BI apps have a very rich dimensionsal data model built over 10 years that incorporates best practises from BI modeling perspective as well as reflect the source system complexities  Thanks for reading a long post, and be on the lookout for future posts.  We will look forward to your valuable feedback on these topics as well as suggestions on what other topics would you like us to cover. I Conformed dimensional model across all business subject areas allows cross functional reporting, e.g. customer / supplier 360 Over 360 fact tables across 7 product areas CRM – 145, SCM – 47, Financials – 28, Procurement – 20, HCM – 27, Projects – 18, Campus Solutions – 21, PLM - 56 Supported by 300 physical dimensions Support for extensive calendars; Gregorian, enterprise and ledger based Conformed data model and metrics for real time vs warehouse based reporting  Multi-tenant enabled Extensive BI related transformations BI apps ETL and data integration support various transformations required for dimensional models and reporting requirements. All these have been distilled into common patterns and abstracted logic which can be readily reused across different modules Slowly Changing Dimension support Hierarchy flattening support Row / Column Hybrid Hierarchy Flattening As Is vs. As Was hierarchy support Currency Conversion :-  Support for 3 corporate, CRM, ledger and transaction currencies UOM conversion Internationalization / Localization Dynamic Data translations Code standardization (Domains) Historical Snapshots Cycle and process lifecycle computations Balance Facts Equalization of GL accounting chartfields/segments Standardized values for categorizing GL accounts Reconciliation between GL and subledgers to track accounted/transferred/posted transactions to GL Materialization of data only available through costly and complex APIs e.g. Fusion Payroll, EBS / Fusion Accruals Complex event Interpretation of source data – E.g. o    What constitutes a transfer o    Deriving supervisors via position hierarchy o    Deriving primary assignment in PSFT o    Categorizing and transposition to measures of Payroll Balances to specific metrics to support side by side comparison of measures of for example Fixed Salary, Variable Salary, Tax, Bonus, Overtime Payments. o    Counting of Events – E.g. converting events to fact counters so that for example the number of hires can easily be added up and compared alongside the total transfers and terminations. Multi pass processing of multiple sources e.g. headcount, salary, promotion, performance to allow side to side comparison. Adding value to data to aid analysis through banding, additional domain classifications and groupings to allow higher level analytical reporting and data discovery Calculation of complex measures examples: o    COGs, DSO, DPO, Inventory turns  etc o    Transfers within a Hierarchy or out of / into a hierarchy relative to view point in hierarchy. Configurability and Extensibility support  BI apps offer support for extensibility for various entities as automated extensibility or part of extension methodology Key Flex fields and Descriptive Flex support  Extensible attribute support (JDE)  Conformed Domains ETL Architecture BI apps offer a modular adapter architecture which allows support of multiple product lines into a single conformed model Multi Source Multi Technology Orchestration – creates load plan taking into account task dependencies and customers deployment to generate a plan based on a customers of multiple complex etl tasks Plan optimization allowing parallel ETL tasks Oracle: Bit map indexes and partition management High availability support    Follow the sun support. TCO BI apps support several utilities / capabilities that help with overall total cost of ownership and ensure a rapid implementation Improved cost of ownership – lower cost to deploy On-going support for new versions of the source application Task based setups flows Data Lineage Functional setup performed in Web UI by Functional person Configuration Test to Production support Security BI apps support both data and object security enabling implementations to quickly configure the application as per the reporting security needs Fine grain object security at report / dashboard and presentation catalog level Data Security integration with source systems  Extensible to support external data security rules Extensive Set of KPIs Over 7000 base and derived metrics across all modules Time series calculations (YoY, % growth etc) Common Currency and UOM reporting Cross subject area KPIs (analyzing HR vs GL data, drill from GL to AP/AR, etc) Prebuilt reports and dashboards 3000+ prebuilt reports supporting a large number of industries Hundreds of role based dashboards Dynamic currency conversion at dashboard level Highly tuned Performance The BI apps have been tuned over the years for both a very performant ETL and dashboard performance. The applications use best practises and advanced database features to enable the best possible performance. Optimized data model for BI and analytic queries Prebuilt aggregates& the ability for customers to create their own aggregates easily on warehouse facts allows for scalable end user performance Incremental extracts and loads Incremental Aggregate build Automatic table index and statistics management Parallel ETL loads Source system deletes handling Low latency extract with Golden Gate Micro ETL support Bitmap Indexes Partitioning support Modularized deployment, start small and add other subject areas seamlessly Source Specfic Staging and Real Time Schema Support for source specific operational reporting schema for EBS, PSFT, Siebel and JDE Application Integrations The BI apps also allow for integration with source systems as well as other applications that provide value add through BI and enable BI consumption during operational decision making Embedded dashboards for Fusion, EBS and Siebel applications Action Link support Marketing Segmentation Sales Predictor Dashboard Territory Management External Integrations The BI apps data integration choices include support for loading extenral data External data enrichment choices : UNSPSC, Item class etc. Extensible Spend Classification Broad Deployment Choices Exalytics support Databases :  Oracle, Exadata, Teradata, DB2, MSSQL ETL tool of choice : ODI (coming), Informatica Extensible and Customizable Extensible architecture and Methodology to add custom and external content Upgradable across releases

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• Javascript - is this a grey area for anyone else?

  - by Anonymous -

  I have a firm understanding of HTML, CSS, PHP, MySQL (and to some extent apache/linux) and find that one of the things missing from my 'web development knowledge base' is javascript - creating richer user interfaces. I'd like to learn Javascript before I look at any frameworks (I've used light javascript/jquery before, but that's besides the point). Can anyone recommend a firm book or online documentation from 'absolute beginner' to 'expert' for javascript? I seem to be finding too many 'display the time' and 'hello world' tutorials...

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• Make pygame's frame rate faster

  - by Smashery

  By profiling my game, I see that the vast majority of the execution time of my hobby game is between the blit and the flip calls. Currently, it's only running at around 13fps. My video card is fairly decent, so my guess is that pygame is not using it. Does anyone know of any graphics/display options I need to set in pygame to make this faster? Or is this just something that I have to live with since I've chosen pygame?

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• Google I/O 2010: Google TV Keynote - YouTube Leanback

  Google I/O 2010: Google TV Keynote - YouTube Leanback Due to licensing and permissions issues, we are unable to show the full Google TV demonstration from the Day 2 keynote at Google I/O. Until we are able to get these permissions, please check out these clips. For Google I/O session videos, presentations, developer interviews and more, go to: code.google.com/io From: GoogleDevelopers Views: 1 0 ratings Time: 02:56 More in Science & Technology

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• GWT Community Updates

  It's been a while since we've put together what's been going on in the GWT community, and there's no time like the present to do so. Below are...

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• Finding an SEO Service Provider to Work With

  SEO Companies are dime a dozen. With so many SEO companies out there, there should not be any issue finding someone to work with. However, if you are looking to get an SEO company that is reasonably price but at the same time is skilled, you may have to look hard.

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• Google I/O 2012 - For Butter or Worse: Smoothing Out Performance in Android UIs

  Google I/O 2012 - For Butter or Worse: Smoothing Out Performance in Android UIs Chet Haase, Romain Guy Great user experience requires buttery smoothness in rendering and animating your interface; your app must have a good, consistent frame rate. This session deep-dives into our work on the Android framework to find and fix performance issues, along with tips on how you can do the same for your applications. For all I/O 2012 sessions, go to developers.google.com From: GoogleDevelopers Views: 4804 116 ratings Time: 58:50 More in Science & Technology

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• Google I/O 2012 - New YouTube Android Player Tools

  Google I/O 2012 - New YouTube Android Player Tools Ross McIlroy, Anton Hansson If you are building Android smartphone, tablet or Google TV applications and want to incorporate high-quality YouTube video playback in your product this session will rock your world. For all I/O 2012 sessions, go to developers.google.com From: GoogleDevelopers Views: 1719 24 ratings Time: 51:10 More in Science & Technology

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• Google I/O 2012 - Protecting your User Experience While Integrating 3rd-party Code

  Google I/O 2012 - Protecting your User Experience While Integrating 3rd-party Code Patrick Meenan The amount of 3rd-party content included on websites is exploding (social sharing buttons, user tracking, advertising, code libraries, etc). Learn tips and techniques for how best to integrate them into your sites without risking a slower user experience or even your sites becoming unavailable. For all I/O 2012 sessions, go to developers.google.com From: GoogleDevelopers Views: 598 12 ratings Time: 48:04 More in Science & Technology

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• How do I commit changes to a text file on button press?

  - by boywithaxe

  I've written a small app that creates a GUI for setting up uShare. Currently it depends heavily on the 'w' (write) and 'a' (append) functions to generate/edit ushare.conf file. But I've been trying to find a way for the app to store all the changes until a save button is pressed, and only then committing them to the actual file. I think that would be the best way of getting around having the user press enter every time they change any field (and indeed allow for GtkCheckButton).

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• Geo for Good Summit Highlights

  Geo for Good Summit Highlights The last week of September, Google hosted the Geo for Good User Summit, for nonprofit mapping and technology specialists to update the nonprofit community about new and special features of Google's mapping products. In this week's Maps Developers Live event, Mano Marks from Maps Developer Relations and Raleigh Seamster, Program Manager with the Google Earth Outreach team will talk about the highlights of the Summit and show off some great examples of people using Maps to help the world. From: GoogleDevelopers Views: 0 0 ratings Time: 00:00 More in Education

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• Web Site Search Engines - Sending Your Site to Search Engine Sites

  Search engines are number one cost effective approach to market your business and web site. Studies indicate that vast majority viewers find web sites via leading search engines and directories. Quality listing on leading search engine or directory may drive targeted traffic to your website and improve your business in a short period of time.

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• ZFS for Database Log Files

  - by user12620111

  I've been troubled by drop outs in CPU usage in my application server, characterized by the CPUs suddenly going from close to 90% CPU busy to almost completely CPU idle for a few seconds. Here is an example of a drop out as shown by a snippet of vmstat data taken while the application server is under a heavy workload. # vmstat 1  kthr      memory            page            disk          faults      cpu  r b w   swap  free  re  mf pi po fr de sr s3 s4 s5 s6   in   sy   cs us sy id  1 0 0 130160176 116381952 0 16 0 0 0 0  0  0  0  0  0 207377 117715 203884 70 21 9  12 0 0 130160160 116381936 0 25 0 0 0 0 0  0  0  0  0 200413 117162 197250 70 20 9  11 0 0 130160176 116381920 0 16 0 0 0 0 0  0  1  0  0 203150 119365 200249 72 21 7  8 0 0 130160176 116377808 0 19 0 0 0 0  0  0  0  0  0 169826 96144 165194 56 17 27  0 0 0 130160176 116377800 0 16 0 0 0 0  0  0  0  0  1 10245 9376 9164 2  1 97  0 0 0 130160176 116377792 0 16 0 0 0 0  0  0  0  0  2 15742 12401 14784 4 1 95  0 0 0 130160176 116377776 2 16 0 0 0 0  0  0  1  0  0 19972 17703 19612 6 2 92  14 0 0 130160176 116377696 0 16 0 0 0 0 0  0  0  0  0 202794 116793 199807 71 21 8  9 0 0 130160160 116373584 0 30 0 0 0 0  0  0 18  0  0 203123 117857 198825 69 20 11 This behavior occurred consistently while the application server was processing synthetic transactions: HTTP requests from JMeter running on an external machine. I explored many theories trying to explain the drop outs, including: Unexpected JMeter behavior Network contention Java Garbage Collection Application Server thread pool problems Connection pool problems Database transaction processing Database I/O contention Graphing the CPU %idle led to a breakthrough: Several of the drop outs were 30 seconds apart. With that insight, I went digging through the data again and looking for other outliers that were 30 seconds apart. In the database server statistics, I found spikes in the iostat "asvc_t" (average response time of disk transactions, in milliseconds) for the disk drive that was being used for the database log files. Here is an example:                     extended device statistics     r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 2053.6    0.0 8234.3  0.0  0.2    0.0    0.1   0  24 c3t60080E5...F4F6d0s0     0.0 2162.2    0.0 8652.8  0.0  0.3    0.0    0.1   0  28 c3t60080E5...F4F6d0s0     0.0 1102.5    0.0 10012.8  0.0  4.5    0.0    4.1   0  69 c3t60080E5...F4F6d0s0     0.0   74.0    0.0 7920.6  0.0 10.0    0.0  135.1   0 100 c3t60080E5...F4F6d0s0     0.0  568.7    0.0 6674.0  0.0  6.4    0.0   11.2   0  90 c3t60080E5...F4F6d0s0     0.0 1358.0    0.0 5456.0  0.0  0.6    0.0    0.4   0  55 c3t60080E5...F4F6d0s0     0.0 1314.3    0.0 5285.2  0.0  0.7    0.0    0.5   0  70 c3t60080E5...F4F6d0s0 Here is a little more information about my database configuration: The database and application server were running on two different SPARC servers. Storage for the database was on a storage array connected via 8 gigabit Fibre Channel Data storage and log file were on different physical disk drives Reliable low latency I/O is provided by battery backed NVRAM Highly available: Two Fibre Channel links accessed via MPxIO Two Mirrored cache controllers The log file physical disks were mirrored in the storage device Database log files on a ZFS Filesystem with cutting-edge technologies, such as copy-on-write and end-to-end checksumming Why would I be getting service time spikes in my high-end storage? First, I wanted to verify that the database log disk service time spikes aligned with the application server CPU drop outs, and they did: At first, I guessed that the disk service time spikes might be related to flushing the write through cache on the storage device, but I was unable to validate that theory. After searching the WWW for a while, I decided to try using a separate log device: # zpool add ZFS-db-41 log c3t60080E500017D55C000015C150A9F8A7d0 The ZFS log device is configured in a similar manner as described above: two physical disks mirrored in the storage array. This change to the database storage configuration eliminated the application server CPU drop outs: Here is the zpool configuration: # zpool status ZFS-db-41   pool: ZFS-db-41  state: ONLINE  scan: none requested config:         NAME                                     STATE         ZFS-db-41                                ONLINE           c3t60080E5...F4F6d0  ONLINE         logs           c3t60080E5...F8A7d0  ONLINE Now, the I/O spikes look like this:                     extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 1053.5    0.0 4234.1  0.0  0.8    0.0    0.7   0  75 c3t60080E5...F8A7d0s0                     extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 1131.8    0.0 4555.3  0.0  0.8    0.0    0.7   0  76 c3t60080E5...F8A7d0s0                     extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 1167.6    0.0 4682.2  0.0  0.7    0.0    0.6   0  74 c3t60080E5...F8A7d0s0     0.0  162.2    0.0 19153.9  0.0  0.7    0.0    4.2   0  12 c3t60080E5...F4F6d0s0                     extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 1247.2    0.0 4992.6  0.0  0.7    0.0    0.6   0  71 c3t60080E5...F8A7d0s0     0.0   41.0    0.0   70.0  0.0  0.1    0.0    1.6   0   2 c3t60080E5...F4F6d0s0                     extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 1241.3    0.0 4989.3  0.0  0.8    0.0    0.6   0  75 c3t60080E5...F8A7d0s0                     extended device statistics                  r/s    w/s   kr/s   kw/s wait actv wsvc_t asvc_t  %w  %b device     0.0 1193.2    0.0 4772.9  0.0  0.7    0.0    0.6   0  71 c3t60080E5...F8A7d0s0 We can see the steady flow of 4k writes to the ZIL device from O_SYNC database log file writes. The spikes are from flushing the transaction group. Like almost all problems that I run into, once I thoroughly understand the problem, I find that other people have documented similar experiences. Thanks to all of you who have documented alternative approaches. Saved for another day: now that the problem is obvious, I should try "zfs:zfs_immediate_write_sz" as recommended in the ZFS Evil Tuning Guide. References: The ZFS Intent Log Solaris ZFS, Synchronous Writes and the ZIL Explained ZFS Evil Tuning Guide: Cache Flushes ZFS Evil Tuning Guide: Tuning ZFS for Database Performance

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