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  • ORA-7445 Troubleshooting

    - by [email protected]
        QUICKLINK: Note 153788.1 ORA-600/ORA-7445 Lookup tool Note 1082674.1 : A Video To Demonstrate The Usage Of The ORA-600/ORA-7445 Lookup Tool [Video]   Have you observed an ORA-07445 error reported in your alert log? While the ORA-600 error is "captured" as a handled exception in the Oracle source code, the ORA-7445 is an unhandled exception error due to an OS exception which should result in the creation of a core file.  An ORA-7445 is a generic error, and can occur from anywhere in the Oracle code. The precise location of the error is identified by the core file and/or trace file it produces.  Looking for the best way to diagnose? Whenever an ORA-7445 error is raised a core file is generated.  There may be a trace file generated with the error as well.   Prior to 11g, the core files are located in the CORE_DUMP_DEST directory.   Starting with 11g, there is a new advanced fault diagnosability infrastructure to manage trace data.  Diagnostic files are written into a root directory for all diagnostic data called the ADR home.   Core files at 11g will go to the ADR HOME/cdump directory.   For more information on the Oracle 11g Diagnosability feature see Note 453125.1 11g Diagnosability Frequently Asked Questions Note 443529.1 11g Quick Steps to Package and Send Critical Error Diagnostic Information to Support[Video]   NOTE:  While the core file is captured in the Diagnosability infrastructure, the file may not be included with a diagnostic package.1.  Check the Alert LogThe alert log may indicate additional errors or other internal errors at the time of the problem.   In some cases, the ORA-7445 error will occur along with ORA-600, ORA-3113, ORA-4030 errors.  The ORA-7445 error can be side effects of the other problems and you should review the first error and associated core file or trace file and work down the list of errors.   Note 1020463.6 DIAGNOSING ORA-3113 ERRORS Note 1812.1 TECH:  Getting a Stack Trace from a CORE file Note 414966.1 RDA Documentation Index   If the ORA-7445 errors are not associated with other error conditions, ensure the trace data is not truncated. If you see a message at the end of the file   "MAX DUMP FILE SIZE EXCEEDED"   the MAX_DUMP_FILE_SIZE parameter is not setup high enough or to 'unlimited'. There could be vital diagnostic information missing in the file and discovering the root issue may be very difficult.  Set the MAX_DUMP_FILE_SIZE appropriately and regenerate the error for complete trace information. For pointers on deeper analysis of these errors see   Note 390293.1 Introduction to 600/7445 Internal Error Analysis Note 211909.1 Customer Introduction to ORA-7445 Errors 2.  Search 600/7445 Lookup Tool Visit My Oracle Support to access the ORA-00600 Lookup tool (Note 153788.1). The ORA-600/ORA-7445 Lookup tool may lead you to applicable content in My Oracle Support on the problem and can be used to investigate the problem with argument data from the error message or you can pull out key stack pointers from the associated trace file to match up against known bugs.3.  "Fine tune" searches in Knowledge Base As the ORA-7445 error indicates an unhandled exception in the Oracle source code, your search in the Oracle Knowledge Base will need to focus on the stack data from the core file or the trace file. Keep in mind that searches on generic argument data will bring back a large result set.  The more you can learn about the environment and code leading to the errors, the easier it will be to narrow the hit list to match your problem. Note 153788.1 ORA-600/ORA-7445 TroubleshooterNote 1082674.1 A Video To Demonstrate The Usage Of The ORA-600/ORA-7445 Lookup Tool [Video] NOTE:  If no trace file is captured, see Note 1812.1 TECH:  Getting a Stack Trace from a CORE file.  Core files are managed through 11g Diagnosability, but are not packaged with other diagnostic data automatically.  The core files can be quite large, but may be useful during analysis within Oracle Support.4.  If assistance is required from Oracle Should it become necessary to get assistance from Oracle Support on an ORA-7445 problem, please provide at a minimum, the Alert log  Associated tracefile(s) or incident package at 11g Patch level  information Core file(s)  Information about changes in configuration and/or application prior to  issues  If error is reproducible, a self-contained reproducible testcase: Note.232963.1 How to Build a Testcase for Oracle Data Server Support to Reproduce ORA-600 and ORA-7445 Errors RDA report or Oracle Configuration Manager information Oracle Configuration Manager Quick Start Guide Note 548815.1 My Oracle Support Configuration Management FAQ Note 414966.1 RDA Documentation Index ***For reference to the content in this blog, refer to Note.1092832.1 Master Note for Diagnosing ORA-600

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  • why is rdiff-backup not compatible with encfs ---reverse

    - by user330273
    I'm trying to use encfs with rdiff-backup to ensure that my backups to a remote server are encrypted. The easiest way to do this would be to use encfs --reverse - which means encfs will create a virtual encrypted file system, which I can then backup using rdiff-backup. Except that it doesn't work. Rdiff-backup fails every time with an "input/output error" on the encfs virtual filesystem. It seems I'm not the only one with this problem, but no one has said what the problem is: this person reported the same issue, but was just told to use sshfs instead (see below on that); in this question on serverfault, one of the answers just states that "rdiff-backup seems to have trouble accessing the EncFS-reverse filesystem." There's an open bug report on the Debian bug tracker(bug 731413, I can't post the link) on this bug, but it's been open since December 2013 with no response. Does anyone know what the problem actually is? Is there a workaround? I can't use the two most commonly suggested alternatives - sshfs and then running encfs on that, or using Duplicity - as both require a much higher bandwidth connection than I have access to (Duplicity requires regular full backups).

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  • Clean file separators in Ruby without File.join

    - by kerry
    I love anything that can be done to clean up source code and make it more readable.  So, when I came upon this post, I was pretty excited.  This is precisely the kind of thing I love. I have never felt good about ‘file separator’ strings b/c of their ugliness and verbosity. In Java we have: 1: String path = "lib"+File.separator+"etc"; And in Ruby a popular method is: 1: path = File.join("lib","etc") Now, by overloading the ‘/’ operator on a String in Ruby: 1: class String 2: def /(str_to_join) 3: File.join(self, str_to_join) 4: end 5: end We can now write: 1: path = 'lib'/'src'/'main' Brilliant!

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  • SQL Server 2012 AlwaysOn Groups and FCIs Part 4

    This is Part 4 of a series on AlwaysOn and FCI integration in SQL Server. In this article we will learn how to add the iSCSI disk storage to our SQL Server nodes and build the cluster. 24% of devs don’t use database source control – make sure you aren’t one of themVersion control is standard for application code, but databases haven’t caught up. So what steps can you take to put your SQL databases under version control? Why should you start doing it? Read more to find out…

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  • Chuck Esterbrook: Geek of the Week

    The Cobra Programming Language is an exciting new general-purpose Open-source language for .NET or Mono, which features unit tests, contracts, informative asserts, generics, Compile-time nil/null tracking, lambda expressions, closures, list comprehensions and generators. Even if it had been developed by a team, it would have been a remarkable achievement. The surprise is that it is the work of one programmer with help from a group of users. We sent Richard to find out more about that one progra...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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  • What should PASS be?

    - by RickHeiges
    Recently, there have been some blog posts about what PASS should be? It is great to see these posts because it gives the BoD feedback on how we are doing and where we can improve. When I first started to get involved in PASS back in 2001, PASS was little more than a conference and some loosely affiliated chapters. It wanted to be more and claimed to be more, but it wasn't. The conference was (and still is) our main source of revenue. The website was essentially a brochure for the conference. The...(read more)

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  • Parsing google site speed in analytics

    - by Kevin Burke
    I'm having a hard time making heads or tails of the Site Speed graphs in Google Analytics. Our site speed is fluctuating wildly from month to month, despite a large sample (the report is "based on 100,000's of visits) and a consistent web set up (static files served from an EC2 instance running nginx behind a load balancer). Here's our site speed, with each datapoint representing a week worth of data. Over this time period we modified our source and HTTP headers to increase our cache hits on static resources by 5x. Why would it fluctuate so much? Is there any way to get more reliable information from those graphs?

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  • Forking a dual licensed app: How to license on my end?

    - by TheLQ
    I forked a project that was dual licensed under the GPL and a commercial license. Since my code was open source and the GPL being what it is, I started by releasing my app under the GPL. But now I'm thinking about dual licensing the project and can't figure out what to do. Since I have copyright on a majority of the code (most of the code was either rewritten or new), can I just pick a commercial license or do I have to buy the upstream commercial license since I'm technically a "derivative" of the project?

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  • Google Analytics - Unable to get GA Tracking

    - by Pure.Krome
    We've been using GA for a few years with no probs. About 2-3 weeks ago we tried to clean up some of our tracking and on one of our profiles, it's not working anymore (since oct 10.) First, some context then some GA Debugging code. 1. Context. We have the following setup: different root domains AND different sub-domains on one of the root domains. www.website.com www.website.com.au www.anotherWebsite.com foo.website.com baa.website.com So what we're doing is the following: each root domain and each sub-domain get their own tracking code. This way we can allow separate people (from outside our company) to access only their own data. Eg. a manager for foo.website.com can only see data related to that domain .. and see data on the other domains. Have a last account which is the SUM of all the domains. this is for us. so we can see total numbers. So to do this, we have two trackers that fire off, on the page. the individual accounts all work fine - they seem to be tracking data ok. the 'global' account is not working and this gives us the = Tracking Not Installed error. This has been going on since oct 10. So the wait 24/48/72 hours thing is waaaaay over. 2. GA Debug code. Installing GA Debug chrome extension gives the following output. I've tried to hide anything that could be considered secret. UA-XXXXX34-1 == Global account (which isn't working any more). UA-XXXXX34-11 == Specific account for www.website.com _gaq.push processing "_setAccount" for args: "[UA-XXXXX34-1]": ga_debug.js:18 _gaq.push processing "_setDomainName" for args: "[website.com]": ga_debug.js:18 _gaq.push processing "_setAllowLinker" for args: "[true]": ga_debug.js:18 _gaq.push processing "_trackPageview" for args: "[]": ga_debug.js:18 Track Pageview ga_debug.js:18 Tracking beacon sent! utmwv=--snipped-- Account ID : UA-XXXX234-1 Page Title : Some page title Host Name : www.website.com Page : / Referring URL : - Hit ID : 1923583969 Visitor ID : 785310647 Session Count : 51 Session Time - First : Thu Aug 23 2012 15:20:17 GMT 1000 (AUS Eastern Standard Time) Session Time - Last : Mon Oct 29 2012 11:41:46 GMT 1100 (AUS Eastern Summer Time) Session Time - Current : Mon Oct 29 2012 12:19:23 GMT 1100 (AUS Eastern Summer Time) Campaign Time : Thu Aug 23 2012 15:20:17 GMT 1000 (AUS Eastern Standard Time) Campaign Session : 1 Campaign Count : 1 Campaign Source : (direct) Campaign Medium : (none); Campaign Name : (direct) Language : en-gb Encoding : UTF-8 Flash Version : 11.4 r31 Java Enabled : true Screen Resolution : 1050x1680 Browser Size : 1033x861 Color Depth : 32-bit Ga.js Version : 5.3.7d Cachebuster : 1846514973 ga_debug.js:18 _gaq.push processing "_setAccount" for args: "[UA-XXXX234-11]": ga_debug.js:18 _gaq.push processing "_setDomainName" for args: "[website.com]": ga_debug.js:18 _gaq.push processing "_setAllowLinker" for args: "[true]": ga_debug.js:18 _gaq.push processing "_trackPageview" for args: "[]": ga_debug.js:18 Track Pageview ga_debug.js:18 Tracking beacon sent! utmwv=--snipped-- Account ID : UA-XXXX234-11 Page Title : SomePageTitle Host Name : www.website.com Page : / Referring URL : - Hit ID : 1923583969 Visitor ID : 785310647 Session Count : 51 Session Time - First : Thu Aug 23 2012 15:20:17 GMT 1000 (AUS Eastern Standard Time) Session Time - Last : Mon Oct 29 2012 11:41:46 GMT 1100 (AUS Eastern Summer Time) Session Time - Current : Mon Oct 29 2012 12:19:23 GMT 1100 (AUS Eastern Summer Time) Campaign Time : Thu Aug 23 2012 15:20:17 GMT 1000 (AUS Eastern Standard Time) Campaign Session : 1 Campaign Count : 1 Campaign Source : (direct) Campaign Medium : (none); Campaign Name : (direct) Language : en-gb Encoding : UTF-8 Flash Version : 11.4 r31 Java Enabled : true Screen Resolution : 1050x1680 Browser Size : 1033x861 Color Depth : 32-bit Ga.js Version : 5.3.7d Cachebuster : 1580443754 and this is the js code he have. BTW, it is inside a <head></head> <script type="text/javascript"> var _gaq = _gaq || []; _gaq.push( ['_setAccount', 'UA-XXXX234-1'], ['_setDomainName', 'website.com'], ['_setAllowLinker', true], ['_trackPageview'] ,['b._setAccount','UA-XXXX234-11'], ['b._setDomainName','website.com'], ['b._setAllowLinker',true], ['b._trackPageview'] ); (function () { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); </script> Finally, I've triple checked that the UA is the correct text. and yes, the global account is -1 and the specific domain is -11. Anyone have any suggestions to help?

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  • What happened to HTML table tags?

    - by John
    I started to code HTML in 1998, and in that time I was used to code a lot table tags, playing with tr and td, I learned many things analysing the source code of many portals on the internet with notepad and Microsoft FrontPage, the latter, aw, how many tables overlapping others, it was fun, I loved that time. However, I abandoned web programming for almost seven years and this year I decided to see what's the web programming today likes. Completely different, there are not table tags anymore, it's full of div and span tags. Why happened ? What are these new tags and why nobody codes in table tags anymore ?

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  • EV SSL Certificates - does anyone care?

    - by pygorex1
    Is any one aware of any data or studies from an impartial source that show the impact of EV SSL certificates on customer behavior? I've been unable to find any such studies. If an EV SSL certificate increases sales on a web store front by even a few points, I can see the value. Aside from data targeted at EV SSL it may be possible to guess at customer behavior based on user interaction with regular SSL certificates. Are users even aware of SSL security? Does regular SSL have any proven effect on web store front sales? Note, that I'm not asking about the necessity of good encryption - I'm asking about a potential customer's perception of security & trust.

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  • A better way to do concurrent programming

    - by Alex.Davies
    Programming to take advantage of multicore processors is hard. If you let multiple threads access the same memory, bad things happen. To avoid this, you use the lock keyword, but if you use that in the wrong way, your code deadlocks. It's all a nightmare. Luckily, there's a better way - Actors. They're really easy to think about. They're really safe (if you follow a couple of simple rules). And high-performance, type-safe actors are now available for .NET by using this open-source library: http://code.google.com/p/n-act/ Have a look at the site for details. I'll blog with more reasons to use actors and tips and tricks to get the best parallelism from them soon.

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  • The sharp decline Statistics of website

    - by Erfan Safarpoor
    My website has had 10 months ago, the statistics are very high. Very high ... But after 10 days of server failure, Marm was 20 times less. I got lost for a long time without making a mistake, do ... I am the source of links that they've hired a writer to pen the final results are seen. But a strange thing: Approximately every two months and was hit again 20 more times and then low again after 10 days! my website url : www.sooran.com (food.sooran.com)

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  • Backward compatibility with event-sourcing

    - by Tomas Jansson
    How do you stay backward compatible with event-sourcing? Let say you release a version that has one kind of event, let call it X. You know how to handle that event in all the systems that extracts the events from the event source. In a later release you make a change to event X or delete it, how do you stay backward compatible with that? To have a fully functional system you need to be able to handle the old event as the same time as you need to handle the updated version. Or if you delete that event type, then you will be stuck with code that is only there to handle legacy events which in my head can be a little bit messy in the long run.

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  • XAudio2 - Multiple instances of the same sound

    - by Boreal
    Right now, I'm adding a rudimentary sound engine to my game. So far, I am able to load in a WAV file and play it once, then free up the memory when I close the game. However, the game crashes with a nice ArgumentOutOfBoundsException when I try to play another sound instance. Specified argument was out of the range of valid values. Parameter name: readLength I'm following this tutorial pretty much exactly, but I still keep getting the aforementioned error. Here's my sound-related code. http://pastebin.com/FgaqfXTs The exception occurs on line 156 when I am playing the sound: source.SubmitSourceBuffer(buffer);

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  • Free WebLogic Administration Cookbook

    - by Antony Reynolds
    Free WebLogic Admin Cookbook Packt Publishing are offering free copies of Oracle WebLogic Server 12c Advanced Administration Cookbook : http://www.packtpub.com/oracle-weblogic-server-12c-advanced-administration-cookbook/book  in exchange for a review either on your blog or on the title’s Amazon page. Here’s the blurb: Install, create and configure WebLogic Server Configure an Administration Server with high availability Create and configure JDBC data sources, multi data sources and gridlink data sources Tune the multi data source to survive database failures Setup JMS distributed queues Use WLDF to send threshold notifications Configure WebLogic Server for stability and resilience If you’re a datacenter operator, system administrator or even a Java developer this book could be exactly what you are looking for to take you one step further with Oracle WebLogic Server, this is a good way to bag yourself a free cookbook (current retail price $25.49). Free review copies are available until Tuesday 2nd July 2013, so if you are interested, email Harleen Kaur Bagga at: harleenb-AT-packtpub.com. I will be posting my own review shortly!

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  • What reasons are there for not using a third party version control service?

    - by Earlz
    I've recently noticed a bit of a trend for my projects as of late. I use to run my own SVN server on my VPS, but recently the nail went in the coffin for that when I got my last project migrated from my server to a Mercurial repo on Bitbucket. What are some of the ramifications to this? (disregarding the change in version control systems) It seems like there has been a huge explosion in version control hosting, and companies like Bitbucket even offer private repos for free, and Github and other such services are extremely cheap now. Also, by using them you get the benefit of their infrastructure's speed and stability. What reasons are there these days to host your own version control? The only real reason I can think of is if your source code is super top secret.

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  • A Quantity class with units

    - by Ryan Ohs
    Goals Create a class that associates a numeric quantity with a unit of measurement. Provide support for simple arithmetic and comparison operations. Implementation An immutable class (Could have been struct but I may try inheritance later) Unit is stored in an enumeration Supported operations: Addition w/ like units Subtraction w/ like units Multiplication by scalar Division by scalar Modulus by scalar Equals() >, >=, <, <=, == IComparable ToString() Implicit cast to Decimal The Source The souce can be downloaded from Github. Notes This class does not support any arithmetic that would modify the unit. This class is not suitable for manipulating currencies. Future Ideas Have a CompositeQuantity class that would allow quantities with unlike units to be combined. Similar currency class with support for allocations/distributions. Provide conversion between units. (Actually I think this would be best placed in an external service. Many situations I deal with require some sort of dynamic conversion ratio.)

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  • Glib.h error while trying to compile an application

    - by user91125
    I've been trying to compile this app from source https://code.launchpad.net/gala and i keep getting this message when i run MAKE: Scanning dependencies of target gala [ 11%] Building C object CMakeFiles/gala.dir/src/DBus.c.o /home/camilo/notifications/build/src/DBus.c:21:18: fatal error: glib.h: No such file or directory compilation terminated. make[2]: *** [CMakeFiles/gala.dir/src/DBus.c.o] Error 1 make[1]: *** [CMakeFiles/gala.dir/all] Error 2 make: *** [all] Error 2 Even though I' have installed glib and there is the glib.h file camilo@ian:~$ find /usr -iname glib.h /usr/include/glib-2.0/glib.h Is it a bug form the application or is it something wrong with my system?

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  • ASP.NET 4.0 and the Entity Framework 4 - Part 2: Perform CRUD Operations Using the Entity Framework

    In this article, Vince demonstrates the usage of the Entity Framework 4 to create, read, update, and delete records in the database which was created in Part 1 of this series. After a short introduction, he discusses the various step involved in the modification of the database, creation of a web form, the selection records to load a drop down list, and the adding, updating, deletion and retrieval of records from the database with the help of relevant source code and screen shots.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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  • Rich text format area size in SDL Tridion 2011 SP1

    - by Alvin Reyes
    I've set a schema field to height 2 and see the following for the input area in Chrome and IE. I'm expecting to have text area that's 2 lines high based on the default text size. I removed the source view option, thinking the tab might affect the size, but it still appears to be about 5 lines in height instead of 2. It seems to match 2 lines if the text is set to a large font or to a heading. I'd like to minimize the size these fields take in the content entry form as well as hint that authors should enter a smaller amount of text. How do I make this match the expected 2 lines?

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  • GNOME Shell Overview animation is slow on my NVIDIA 320M

    - by AllanCaeg
    I'm running Ubuntu 10.10 on my MacBook Air 11" (late 2010 model 3,1). Compiz runs fine, as well as most of GNOME Shell's animations. The animation for switching to and from GNOME Shell overview is just very slow. Unfortunately, it's the most common animation on Shell. I already applied cd ~/gnome-shell/source/gnome-shell curl http://bugzilla-attachments.gnome.org/attachment.cgi?id=157326 > shell-animations-nvidia.patch git am shell-animations-nvidia.pat that I found from http://live.gnome.org/GnomeShell/SwatList , but the issue's still here. How do I fix this? EDIT: Apparently, it's an NVIDIA driver bug, which has something to do with the message tray. Is this correct? How do I go around this issue?

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  • Awarded Visual Studio ALM MVP for 2012!

    - by Jakob Ehn
    Today I received an email from Microsoft stating that: Dear Jakob Ehn, Congratulations! We are pleased to present you with the 2012 Microsoft® MVP Award! This award is given to exceptional technical community leaders who actively share their high quality, real world expertise with others. We appreciate your outstanding contributions in Visual Studio ALM technical communities during the past year.   This is incredibles news and I really want to thank both the people at Microsoft who nominated me and some of the (now) fellow MVP’s that I have worked with over the last year, both as part of the Visual Studio ALM Rangers program and as part of the TFS Build Extensions community project, in particular Mike Fourie and of course my colleague and main source of inspiration Terje Sandström    I’m really looking forward to this year, it’s going to be a blast!

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  • Project planning and customer tracking system

    - by Daniel Hollands
    First off, sorry if this is the wrong 'stack' site, but it seemed like a good place to start. I'm happy to report that my services as a web developer are starting to be in quite a lot of demand, and I have a few existing and potentially new customers all lining up - but I'm finding it very hard to keep track of everything. What I'm hoping for is some (preferably web-based) system which I can use to keep track of who my customers are, the various projects that I've got going on for them, and (if possible) the individual sub-tasks that make up each project. What would be even better is if the relevant customer was able to log into the site, and see the process of their projects. I do hope you know what I'm talking about, and that you'll be able to offer some suggestions of either web-base sites that offer something along these lines, or of some open source solution or something like that? Thank you

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  • How to Achieve Real-Time Data Protection and Availabilty....For Real

    - by JoeMeeks
    There is a class of business and mission critical applications where downtime or data loss have substantial negative impact on revenue, customer service, reputation, cost, etc. Because the Oracle Database is used extensively to provide reliable performance and availability for this class of application, it also provides an integrated set of capabilities for real-time data protection and availability. Active Data Guard, depicted in the figure below, is the cornerstone for accomplishing these objectives because it provides the absolute best real-time data protection and availability for the Oracle Database. This is a bold statement, but it is supported by the facts. It isn’t so much that alternative solutions are bad, it’s just that their architectures prevent them from achieving the same levels of data protection, availability, simplicity, and asset utilization provided by Active Data Guard. Let’s explore further. Backups are the most popular method used to protect data and are an essential best practice for every database. Not surprisingly, Oracle Recovery Manager (RMAN) is one of the most commonly used features of the Oracle Database. But comparing Active Data Guard to backups is like comparing apples to motorcycles. Active Data Guard uses a hot (open read-only), synchronized copy of the production database to provide real-time data protection and HA. In contrast, a restore from backup takes time and often has many moving parts - people, processes, software and systems – that can create a level of uncertainty during an outage that critical applications can’t afford. This is why backups play a secondary role for your most critical databases by complementing real-time solutions that can provide both data protection and availability. Before Data Guard, enterprises used storage remote-mirroring for real-time data protection and availability. Remote-mirroring is a sophisticated storage technology promoted as a generic infrastructure solution that makes a simple promise – whatever is written to a primary volume will also be written to the mirrored volume at a remote site. Keeping this promise is also what causes data loss and downtime when the data written to primary volumes is corrupt – the same corruption is faithfully mirrored to the remote volume making both copies unusable. This happens because remote-mirroring is a generic process. It has no  intrinsic knowledge of Oracle data structures to enable advanced protection, nor can it perform independent Oracle validation BEFORE changes are applied to the remote copy. There is also nothing to prevent human error (e.g. a storage admin accidentally deleting critical files) from also impacting the remote mirrored copy. Remote-mirroring tricks users by creating a false impression that there are two separate copies of the Oracle Database. In truth; while remote-mirroring maintains two copies of the data on different volumes, both are part of a single closely coupled system. Not only will remote-mirroring propagate corruptions and administrative errors, but the changes applied to the mirrored volume are a result of the same Oracle code path that applied the change to the source volume. There is no isolation, either from a storage mirroring perspective or from an Oracle software perspective.  Bottom line, storage remote-mirroring lacks both the smarts and isolation level necessary to provide true data protection. Active Data Guard offers much more than storage remote-mirroring when your objective is protecting your enterprise from downtime and data loss. Like remote-mirroring, an Active Data Guard replica is an exact block for block copy of the primary. Unlike remote-mirroring, an Active Data Guard replica is NOT a tightly coupled copy of the source volumes - it is a completely independent Oracle Database. Active Data Guard’s inherent knowledge of Oracle data block and redo structures enables a separate Oracle Database using a different Oracle code path than the primary to use the full complement of Oracle data validation methods before changes are applied to the synchronized copy. These include: physical check sum, logical intra-block checking, lost write validation, and automatic block repair. The figure below illustrates the stark difference between the knowledge that remote-mirroring can discern from an Oracle data block and what Active Data Guard can discern. An Active Data Guard standby also provides a range of additional services enabled by the fact that it is a running Oracle Database - not just a mirrored copy of data files. An Active Data Guard standby database can be open read-only while it is synchronizing with the primary. This enables read-only workloads to be offloaded from the primary system and run on the active standby - boosting performance by utilizing all assets. An Active Data Guard standby can also be used to implement many types of system and database maintenance in rolling fashion. Maintenance and upgrades are first implemented on the standby while production runs unaffected at the primary. After the primary and standby are synchronized and all changes have been validated, the production workload is quickly switched to the standby. The only downtime is the time required for user connections to transfer from one system to the next. These capabilities further expand the expectations of availability offered by a data protection solution beyond what is possible to do using storage remote-mirroring. So don’t be fooled by appearances.  Storage remote-mirroring and Active Data Guard replication may look similar on the surface - but the devil is in the details. Only Active Data Guard has the smarts, the isolation, and the simplicity, to provide the best data protection and availability for the Oracle Database. Stay tuned for future blog posts that dive into the many differences between storage remote-mirroring and Active Data Guard along the dimensions of data protection, data availability, cost, asset utilization and return on investment. For additional information on Active Data Guard, see: Active Data Guard Technical White Paper Active Data Guard vs Storage Remote-Mirroring Active Data Guard Home Page on the Oracle Technology Network

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