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  • SQL SERVER – A Successful Performance Tuning Seminar – Hyderabad – Nov 27-28, 2010 – Next Pune

    - by pinaldave
    My recent SQL Server Performance Tuning Seminar in Colombo was oversubscribed with total of 35 attendees. You can read the details over here SQLAuthority News – SQL Server Performance Optimizations Seminar – Grand Success – Colombo, Sri Lanka – Oct 4 – 5, 2010. I had recently completed another seminar in Hyderabad which was again blazing success. We had 25 attendees to the seminar and had wonderful time together. There is one thing very different between usual class room training and this seminar series. In this seminar series we go 100% demo oriented and real world scenario deep down. We do not talk usual theory talk-talk. The goal of this seminar to give anybody who attends a jump start and deep dive on the performance tuning subject. I will share many different examples and scenarios from my years of experience of performance tuning. The beginning of the second day is always interesting as I take attendees the server as example of the talk, and together we will attempt to identify the bottleneck and see if we can resolve the same. So far I have got excellent feedback on this unique session, where we pick database of the attendees and address the issues. I plan to do the same again in next sessions. The next Seminar is in Pune.I am very excited for the same. Date and Time: December 4-5, 2010. 10 AM to 6 PM The Pride Hotel 05, University Road, Shivaji Nagar, Pune – 411 005 Tel: 020 255 34567 Click here for the agenda of the seminar. Instead of writing more details, I will let the photos do the talk for latest Hyderabad Seminar. Hotel Amrutha Castle King Arthur's Court Pinal Presenting Seminar Pinal Presenting Seminar Seminar Attendees Pinal Presenting Seminar Group Photo of Hyderabad Seminar Attendees Seminar Support Staff - Nupur and Shaivi Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Training, SQLAuthority Author Visit, SQLAuthority News, T SQL, Technology

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  • Upcoming Webinar: Practical Performance Profiling presented by Jean-Philippe Gouigoux

    - by Michaela Murray
    Hot on the heels of releasing his new book, Practical Performance Profiling, I'm delighted that Jean-Philippe Gouigoux will be joining us on April 3rd to present a free webinar on optimizing .NET code performance. He gave me a sneak preview of his talk last week and there's a lot of really useful advice in there. He'll be discussing why he thinks 20% of performance problems account for 80% of lost time, before looking at some real examples of both server-side and client-side profiling, and covering a variety of best practices you can use to improve the performance of your own code. The webinar will be followed by a Q&A session where he'll be joined by Red Gate technical support engineer Chris Allen to answer any of your questions. Jean-Philippe has 10 years' experience in .NET, most recently as system architect at MGDIS, and was recently made a Microsoft MVP for his contributions to the .NET community. I'm really excited that he's found a gap between his day job and university lecturing to share his knowledge, and I hope you'll be able to join us on April 3rd - it's free but you do need to register in advance at https://www3.gotomeeting.com/register/829014934. I'll see you there!

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  • Case Study: Polystar Improves Telecom Networks Performance with Embedded MySQL

    - by Bertrand Matthelié
    Polystar delivers and supports systems that increase the quality, revenue and customer satisfaction of telecommunication services. Headquarted in Sweden, Polystar helps operators worldwide including Telia, Tele2, Telekom Malysia and T-Mobile to monitor their network performance and improve service levels. Challenges Deliver complete turnkey solutions to customers integrating a database ensuring high performance at scale, while being very easy to use, manage and optimize. Enable the implementation of distributed architectures including one database per server while maintaining a low Total Cost of Ownership (TCO). Avoid growing database complexity as the volume of mobile data to monitor and analyze drastically increases. Solution Evaluation of several databases and selection of MySQL based on its high performance, manageability, and low TCO. The MySQL databases implemented within the Polystar solutions handle on average 3,000 to 5,000 transactions per second. Up to 50 million records are inserted every day in each database. Typical installations include between 50 and 100 MySQL databases, up to 300 for the largest ones. Data is then periodically aggregated, with the original records being overwritten, as the need for detailed information becomes unnecessary to operators after a few weeks. The exponential growth in mobile data traffic driven by the proliferation of smartphones and usage of social media requires ever more powerful solutions to monitor, analyze and turn network data into actionable business intelligence. With MySQL, Polystar can deliver powerful, yet easy to manage, solutions to its customers. MySQL-based Polystar solutions enable operators to monitor, manage and improve the service levels of their telecom networks in over a dozen countries from a single location. The new and innovative MySQL features constantly delivered by Oracle help ensure Polystar that it will be able to meet its customer’s needs as they evolve. “MySQL has been a great embedded database choice for us. It delivers the high performance we need while remaining very easy to use, manage and tune. Power and simplicity at its best.” Mats Söderlindh, COO at Polystar.

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  • CRM On Demand Performance Tips - Live Web Session on April 20, 2010

    - by Cheryl
    The CRM On Demand Customer Care specialists have another live Web session coming up - this one is about performance - issues, tips, and considerations. This is a part of their Web series, where they pick topics that they hear a lot of questions or concerns about from customers and run live (and free) 1-hour Web sessions about them. Here are the details for this event: Event Title: CRM On Demand Performance Brandon (Hank) Henrie will present some of the top CRM On Demand performance questions and issues that customers raise and some tips and tricks that you can use to avoid them. He will point out good resources that can help and tips for logging performance-related service requests, when all else fails. Date: April 20, 2010 Time: 10:00 am (UTC-07:00 Arizona) How to join: 1. Dial 1-866-682-4770 to access the conference line. 2. Enter the conference code - 6241996 and press # 3. Follow the instructions to record your name and press # 4. Enter the meeting passcode - 1212 and press # 5. Follow the instructions below to join the web portion of the conference. The Web Conference Go to the Oracle Web Conference site: https://strtc.oracle.com Prior to the event: Click the New User button then run the New User Test. (If you have difficulties installing the web conference software try downloading the conference software from the test status window and installing manually.) To join the event: 1. Enter the conference information In the Join Conference box: Conference ID: 6566623 Your Name 2. Click the Join Conference button. Watch for announcements of future sessions on different topics. And, let us know what you think!

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  • Items Affecting Performance of the MySQL Database

    - by Antoinette O'Sullivan
    To learn about the many factors that can affect the performance of the MySQL Database, take the MySQL Performance Tuning course. You will learn: How your hardware and operating system can affect performance How to set up and logging to improve performance Best practices for backup and recovery And much more You can take this 4-day instructor-led course through the following formats: Training-on-Demand: Start training within 24 hours of registering for training, following lectures at your own pace through streaming video and booking time on a lab environment to suit your schedule. Live-Virtual Event: Attend a live event from your own desk, no travel required. Choose from a selection of events on the schedule to suit different time-zones. In-Class Event: Travel to an education center to attend this course. Below is a selection of events already on the schedule.  Location  Date  Delivery Language  Brussels, Beligum  10 November 2014  English  Sao Paolo, Brazil  25 August 2014  Brazilian Portuguese  London, England  20 October 2014  English  Milan, Italy  20 October 2014  Italian  Rome, Italy  1 December 2014  Italian  Riga, Latvia  29 September 2014  Latvian  Petaling Jaya, Malaysia  22 September 2014  English  Utrecht, Netherlands  10 November 2014  English  Warsaw, Poland  1 September 2014  Polish  Barcelona, Spain  14 October 2014  Spanish To register for an event, request an additional event, or learn more about the authentic MySQL Curriculum, go to http://education.oracle.com/mysql.

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  • IOUG SIG Webcast on October 30th : Performance Tuning your DB Cloud

    - by Anand Akela
    The Oracle Enterprise Manager Special Interest Group (SIG) is a growing body of IOUG members who manage or are interested in all aspects of Oracle Enterprise Manager. This IOUG SIG is managed by volunteers and supported by Oracle Enterprise Manager product managers and developers. The purpose of the SIG is to bring relevant information and education through webcasts, discussions and networking to users interested in learning more about the product, and to share user experiences. On October 30th at 10 AM pacific time, Oracle Enterprise Manager SIG is hosting a webcast on "Performance Tuning your DB Cloud in OEM 12c Cloud Control - 360 Degrees". In this webcast, Tariq Farooq , CEO, BrainSurface and Mike Ault, Oracle  will provide a tutorial on how to monitor and perform performance tuning of the Oracle database cloud environment. You will learn how to leverage Oracle Enterprise Manager for tuning, trouble-shooting & monitoring your Oracle Database Cloud Ecosystem. The session covers lessons learned, tips/tricks, recommendations, best practices, gotchas and a whole lot more on how to effectively use Oracle Enterprise Manager Cloud Control 12c for quick, easy & intuitive performance tuning of your Oracle Database Cloud. Session Objectives:• Leveraging OEM12c Cloud Control for Oracle DB Tuning/Monitoring • Limited Deep-Dive on AWR • Oracle DB Cloud Performance Tuning • Best Practices for DB Cloud Maintenance/Monitoring Register Now ! Stay Connected: Twitter |  Face book |  You Tube |  Linked in |  Google+ |  Newsletter

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  • Can Clojure's thread-based agents handle c10k performance?

    - by elliot42
    I'm writing a c10k-style service and am trying to evaluate Clojure's performance. Can Clojure agents handle this scale of concurrency with its thread-based agents? Other high performance systems seem to be moving towards async-IO/events/greenlets, albeit at a seemingly higher complexity cost. Suppose there are 10,000 clients connected, sending messages that should be appended to 1,000 local files--the Clojure service is trying to write to as many files in parallel as it can, while not letting any two separate requests mangle the same single file by writing at the same time. Clojure agents are extremely elegant conceptually--they would allow separate files to be written independently and asynchronously, while serializing (in the database sense) multiple requests to write to the same file. My understanding is that agents work by starting a thread for each operation (assume we are IO-bound and using send-off)--so in this case is it correct that it would start 1,000+ threads? Can current-day systems handle this number of threads efficiently? Most of them should be IO-bound and sleeping most of the time, but I presume there would still be a context-switching penalty that is theoretically higher than async-IO/event-based systems (e.g. Erlang, Go, node.js). If the Clojure solution can handle the performance, it seems like the most elegant thing to code. However if it can't handle the performance then something like Erlang or Go's lightweight processes might be preferable, since they are designed to have tens of thousands of them spawned at once, and are only moderately more complex to implement. Has anyone approached this problem in Clojure or compared to these other platforms? (Thanks for your thoughts!)

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  • SOA performance on SPARC T5 benchmark results

    - by JuergenKress
    The brand NEW super fast SPARC T5 servers are available. The platform is superb to run large SOA Suite environments or to consolidate your whole middleware platform. Some performance advices, recommended for all workloads: Performance profile for SOA apps on Oracle Solaris 11 BPEL (Fusion Order Demo) instances per second OSB (messages / transformations per second) Crypto acceleration study for SOA transformations SPARC T4 and T5 platform testing, pre-tuning Performance suitable for mid-to-high range enterprise in stand-alone SOA deployment or virtualized consolidation environment shared with Oracle applications 2.2x to 5x faster than SPARC T3 servers 25% faster SOA throughput, core to core than Intel 5600-series servers (running Exalogic software) SPARC T5 has 2x the consolidation density of Intel 5600-class processors 2x faster initial deployment time using Optimized Solutions pre-tested configuration steps Over 200 Application adapters for easiest Oracle software integration Would you like to get details? We can share with you on 1:1 bases T5 SOA Suite performance benchmarks, please contact your local partner manager or myself! SOA & BPM Partner Community For regular information on Oracle SOA Suite become a member in the SOA & BPM Partner Community for registration please visit www.oracle.com/goto/emea/soa (OPN account required) If you need support with your account please contact the Oracle Partner Business Center. Blog Twitter LinkedIn Facebook Wiki Mix Forum Technorati Tags: T5,TS Sparc,T5 SOA,bechmark,SOA Community,Oracle SOA,Oracle BPM,Community,OPN,Jürgen Kress

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  • Help w/ iPad 1 performance for tile-based DOM Javascript game

    - by butr0s
    I've made a 2D tile-based game with DOM/Javascript. For each level, the map data is loaded and parsed, then lots of tiles ( elements) are drawn onto a larger "map" element. The map is inside of a container that hides overflow, so I can move the map element around by positioning it absolutely. Works a treat on desktop browsers, and my iPad 2. My problem is that performance is really bad on iPad 1. The performance hit is directly related to all the tile elements in my map, because when I remove or reduce the number of tiles drawn, performance improves. Optimizing my collision detection loop has no effect. My first thought was to batch groups of tiles into containers, then hide/show them based on proximity to the player, however this still causes a huge hiccup when the player moves and a new group of tiles is displayed (offscreen). Actually removing the out-of-sight elements from the DOM, then re-adding them as necessary is no faster. Anyone know of any tips that might speed up DOM performance here? My map is 1920 x 1920 pixels, so as far as I know should be within the WebKit texture limit on iOS 5/iPad. The map is being moved with CSS3 transforms, and I've picked all the other obvious low-hanging fruit.

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  • Using IIS Logs for Performance Testing with Visual Studio

    - by Tarun Arora
    In this blog post I’ll show you how you can play back the IIS Logs in Visual Studio to automatically generate the web performance tests. You can also download the sample solution I am demo-ing in the blog post. Introduction Performance testing is as important for new websites as it is for evolving websites. If you already have your website running in production you could mine the information available in IIS logs to analyse the dense zones (most used pages) and performance test those pages rather than wasting time testing & tuning the least used pages in your application. What are IIS Logs To help with server use and analysis, IIS is integrated with several types of log files. These log file formats provide information on a range of websites and specific statistics, including Internet Protocol (IP) addresses, user information and site visits as well as dates, times and queries. If you are using IIS 7 and above you will find the log files in the following directory C:\Interpub\Logs\ Walkthrough 1. Download and Install Log Parser from the Microsoft download Centre. You should see the LogParser.dll in the install folder, the default install location is C:\Program Files (x86)\Log Parser 2.2. LogParser.dll gives us a library to query the iis log files programmatically. By the way if you haven’t used Log Parser in the past, it is a is a powerful, versatile tool that provides universal query access to text-based data such as log files, XML files and CSV files, as well as key data sources on the Windows operating system such as the Event Log, the Registry, the file system, and Active Directory. More details… 2. Create a new test project in Visual Studio. Let’s call it IISLogsToWebPerfTestDemo.   3.  Delete the UnitTest1.cs class that gets created by default. Right click the solution and add a project of type class library, name it, IISLogsToWebPerfTestEngine. Delete the default class Program.cs that gets created with the project. 4. Under the IISLogsToWebPerfTestEngine project add a reference to Microsoft.VisualStudio.QualityTools.WebTestFramework – c:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE\PublicAssemblies\Microsoft.VisualStudio.QualityTools.WebTestFramework.dll LogParser also called MSUtil - c:\users\tarora\documents\visual studio 2010\Projects\IisLogsToWebPerfTest\IisLogsToWebPerfTestEngine\obj\Debug\Interop.MSUtil.dll 5. Right click IISLogsToWebPerfTestEngine project and add a new classes – IISLogReader.cs The IISLogReader class queries the iis logs using the log parser. using System; using System.Collections.Generic; using System.Text; using MSUtil; using LogQuery = MSUtil.LogQueryClassClass; using IISLogInputFormat = MSUtil.COMIISW3CInputContextClassClass; using LogRecordSet = MSUtil.ILogRecordset; using Microsoft.VisualStudio.TestTools.WebTesting; using System.Diagnostics; namespace IisLogsToWebPerfTestEngine { // By making use of log parser it is possible to query the iis log using select queries public class IISLogReader { private string _iisLogPath; public IISLogReader(string iisLogPath) { _iisLogPath = iisLogPath; } public IEnumerable<WebTestRequest> GetRequests() { LogQuery logQuery = new LogQuery(); IISLogInputFormat iisInputFormat = new IISLogInputFormat(); // currently these columns give us suffient information to construct the web test requests string query = @"SELECT s-ip, s-port, cs-method, cs-uri-stem, cs-uri-query FROM " + _iisLogPath; LogRecordSet recordSet = logQuery.Execute(query, iisInputFormat); // Apply a bit of transformation while (!recordSet.atEnd()) { ILogRecord record = recordSet.getRecord(); if (record.getValueEx("cs-method").ToString() == "GET") { string server = record.getValueEx("s-ip").ToString(); string path = record.getValueEx("cs-uri-stem").ToString(); string querystring = record.getValueEx("cs-uri-query").ToString(); StringBuilder urlBuilder = new StringBuilder(); urlBuilder.Append("http://"); urlBuilder.Append(server); urlBuilder.Append(path); if (!String.IsNullOrEmpty(querystring)) { urlBuilder.Append("?"); urlBuilder.Append(querystring); } // You could make substitutions by introducing parameterized web tests. WebTestRequest request = new WebTestRequest(urlBuilder.ToString()); Debug.WriteLine(request.UrlWithQueryString); yield return request; } recordSet.moveNext(); } Console.WriteLine(" That's it! Closing the reader"); recordSet.close(); } } }   6. Connect the dots by adding the project reference ‘IisLogsToWebPerfTestEngine’ to ‘IisLogsToWebPerfTest’. Right click the ‘IisLogsToWebPerfTest’ project and add a new class ‘WebTest1Coded.cs’ The WebTest1Coded.cs inherits from the WebTest class. By overriding the GetRequestMethod we can inject the log files to the IISLogReader class which uses Log parser to query the log file and extract the web requests to generate the web test request which is yielded back for play back when the test is run. namespace IisLogsToWebPerfTest { using System; using System.Collections.Generic; using System.Text; using Microsoft.VisualStudio.TestTools.WebTesting; using Microsoft.VisualStudio.TestTools.WebTesting.Rules; using IisLogsToWebPerfTestEngine; // This class is a coded web performance test implementation, that simply passes // the path of the iis logs to the IisLogReader class which does the heavy // lifting of reading the contents of the log file and converting them to tests. // You could have multiple such classes that inherit from WebTest and implement // GetRequestEnumerator Method and pass differnt log files for different tests. public class WebTest1Coded : WebTest { public WebTest1Coded() { this.PreAuthenticate = true; } public override IEnumerator<WebTestRequest> GetRequestEnumerator() { // substitute the highlighted path with the path of the iis log file IISLogReader reader = new IISLogReader(@"C:\Demo\iisLog1.log"); foreach (WebTestRequest request in reader.GetRequests()) { yield return request; } } } }   7. Its time to fire the test off and see the iis log playback as a web performance test. From the Test menu choose Test View Window you should be able to see the WebTest1Coded test show up. Highlight the test and press Run selection (you can also debug the test in case you face any failures during test execution). 8. Optionally you can create a Load Test by keeping ‘WebTest1Coded’ as the base test. Conclusion You have just helped your testing team, you now have become the coolest developer in your organization! Jokes apart, log parser and web performance test together allow you to save a lot of time by not having to worry about what to test or even worrying about how to record the test. If you haven’t already, download the solution from here. You can take this to the next level by using LogParser to extract the log files as part of an end of day batch to a database. See the usage trends by user this solution over a longer term and have your tests consume the web requests now stored in the database to generate the web performance tests. If you like the post, don’t forget to share … Keep RocKiNg!

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  • SQL Sentry Truth-Telling and Disk Configuration

    - by AjarnMark
    Recently, SQL Sentry told me something about my SQL Server disk configurations that I just didn’t want to believe, but alas, it was true. Several days ago I posted my First Impressions of the SQL Sentry Power Suite.  Today’s post could fall into the category of, “Hey, as long as you have that fancy tool…”  Unfortunately, it also falls into the category of an overloaded worker taking someone else’s word for the truth, not verifying it with independent fact-checking, and then making decisions based on that.  Here’s my story… I’m not exactly an Accidental DBA (or Involuntary DBA as Paul Randal calls it).  I came to this company five years ago as a lead application developer with extensive experience in database design and development.  I worked my way into management, and along the way, took over the DBA responsibilities.  Fortunately, our systems run pretty smoothly most of the time, but I’m always looking for ways to make them better and to fit into my understanding of best practices.  When I took over as DBA, I inherited a SQL 2000 server with about 30 databases on it supporting our main systems, and a SQL 2005 server with multiple instances.  Both of these servers were configured with the Operating System and Application files on the C drive, data files on a different drive letter, and log files on a third drive letter.  Even before I took over as DBA, I verified that this was true with a previous server administrator, and that these represented actual separate disks.  He stated that they did, and I thought that all was well. Then one day, I’m poking around inside the SQL Sentry Performance Advisor, checking out features as I am evaluating whether to purchase the product, and I come across a Disk Configuration section.  The first thing I notice is that the drives do not have the proper partition offset, which was not at all surprising to me given the age of the installation and the relative newness of that topic.  But what threw me for a loop was that the graphic display appeared to be telling me that I did not in fact have three separate drives (or arrays) but rather had two, and that the log files were merely on a separate volume on the same physical array as the OS.  I figured that I must be reading it wrong so I scanned the Help file, but that just seemed to confirm my interpretation.  Then I thought, “there must be something wrong with the demo version of the software!  This can’t be right!”  But just to double-check, I went to our current server admin to talk it over with him, and sure enough, SQL Sentry was telling the truth! I was stunned!  I quickly went through the grieving process…denial…anger…reconciliation.  Here was something that I thought was such a basic truth that was turned upside down.  OK, granted, this wasn’t disastrous.  Our databases didn’t suddenly grind to a halt.  I didn’t get calls late at night inquiring about the sudden downturn in performance.  But it was a bit of a shock to the system, in a good way, to jolt me out of taking what I had believed as the truth for granted, and instead to Trust, but Verify! Yes, before someone else points it out, I know that there are”free” disk management tools built-in to Windows that would have told me the same thing if I had only looked at them; I did not have to buy a fancy tool to tell me that, but the fact is, until I was evaluating the tool, I had just gone with what I was told, and never bothered to check what was actually there. So, what things do you believe to be true but you actually never verified?

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  • Organization &amp; Architecture UNISA Studies &ndash; Chap 6

    - by MarkPearl
    Learning Outcomes Discuss the physical characteristics of magnetic disks Describe how data is organized and accessed on a magnetic disk Discuss the parameters that play a role in the performance of magnetic disks Describe different optical memory devices Magnetic Disk The way data is stored on and retried from magnetic disks Data is recorded on and later retrieved form the disk via a conducting coil named the head (in many systems there are two heads) The writ mechanism exploits the fact that electricity flowing through a coil produces a magnetic field. Electric pulses are sent to the write head, and the resulting magnetic patterns are recorded on the surface below with different patterns for positive and negative currents The physical characteristics of a magnetic disk   Summarize from book   The factors that play a role in the performance of a disk Seek time – the time it takes to position the head at the track Rotational delay / latency – the time it takes for the beginning of the sector to reach the head Access time – the sum of the seek time and rotational delay Transfer time – the time it takes to transfer data RAID The rate of improvement in secondary storage performance has been considerably less than the rate for processors and main memory. Thus secondary storage has become a bit of a bottleneck. RAID works on the concept that if one disk can be pushed so far, additional gains in performance are to be had by using multiple parallel components. Points to note about RAID… RAID is a set of physical disk drives viewed by the operating system as a single logical drive Data is distributed across the physical drives of an array in a scheme known as striping Redundant disk capacity is used to store parity information, which guarantees data recoverability in case of a disk failure (not supported by RAID 0 or RAID 1) Interesting to note that the increase in the number of drives, increases the probability of failure. To compensate for this decreased reliability RAID makes use of stored parity information that enables the recovery of data lost due to a disk failure.   The RAID scheme consists of 7 levels…   Category Level Description Disks Required Data Availability Large I/O Data Transfer Capacity Small I/O Request Rate Striping 0 Non Redundant N Lower than single disk Very high Very high for both read and write Mirroring 1 Mirrored 2N Higher than RAID 2 – 5 but lower than RAID 6 Higher than single disk Up to twice that of a signle disk for read Parallel Access 2 Redundant via Hamming Code N + m Much higher than single disk Highest of all listed alternatives Approximately twice that of a single disk Parallel Access 3 Bit interleaved parity N + 1 Much higher than single disk Highest of all listed alternatives Approximately twice that of a single disk Independent Access 4 Block interleaved parity N + 1 Much higher than single disk Similar to RAID 0 for read, significantly lower than single disk for write Similar to RAID 0 for read, significantly lower than single disk for write Independent Access 5 Block interleaved parity N + 1 Much higher than single disk Similar to RAID 0 for read, lower than single disk for write Similar to RAID 0 for read, generally  lower than single disk for write Independent Access 6 Block interleaved parity N + 2 Highest of all listed alternatives Similar to RAID 0 for read; lower than RAID 5 for write Similar to RAID 0 for read, significantly lower than RAID 5  for write   Read page 215 – 221 for detailed explanation on RAID levels Optical Memory There are a variety of optical-disk systems available. Read through the table on page 222 – 223 Some of the devices include… CD CD-ROM CD-R CD-RW DVD DVD-R DVD-RW Blue-Ray DVD Magnetic Tape Most modern systems use serial recording – data is lade out as a sequence of bits along each track. The typical recording used in serial is referred to as serpentine recording. In this technique when data is being recorded, the first set of bits is recorded along the whole length of the tape. When the end of the tape is reached the heads are repostioned to record a new track, and the tape is again recorded on its whole length, this time in the opposite direction. That process continued back and forth until the tape is full. To increase speed, the read-write head is capable of reading and writing a number of adjacent tracks simultaneously. Data is still recorded serially along individual tracks, but blocks in sequence are stored on adjacent tracks as suggested. A tape drive is a sequential access device. Magnetic tape was the first kind of secondary memory. It is still widely used as the lowest-cost, slowest speed member of the memory hierarchy.

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  • Make The Web Fast - The HAR Show: Capturing and Analyzing performance data with HTTP Archive format

    Make The Web Fast - The HAR Show: Capturing and Analyzing performance data with HTTP Archive format Need a flexible format to record, export, and analyze network performance data? Well, that's exactly what the HTTP Archive format (HAR) is designed to do! Even better, did you know that Chrome DevTools supports it? In this episode we'll take a deep dive into the format (as you'll see, its very simple), and explore the many different ways it can help you capture and analyze your sites performance. Join +Ilya Grigorik and +Peter Lubbers to find out how to capture HAR network traces in Chrome, visualize the data via an online tool, share the reports with your clients and coworkers, automate the logging and capture of HAR data for your build scripts, and even adapt it to server-side analysis use cases! Yes, a rapid fire session of awesome demos - see you there. From: GoogleDevelopers Views: 0 6 ratings Time: 00:00 More in Science & Technology

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  • Retrieve Performance Data from SOA Infrastructure Database

    - by fip
    My earlier blog posting shows how to enable, retrieve and interpret BPEL engine performance statistics to aid performance troubleshooting. The strength of BPEL engine statistics at EM is its break down per request. But there are some limitations with the BPEL performance statistics mentioned in that blog posting: The statistics were stored in memory instead of being persisted. To avoid memory overflow, the data are stored to a buffer with limited size. When the statistic entries exceed the limitation, old data will be flushed out to give ways to new statistics. Therefore it can only keep the last X number of entries of data. The statistics 5 hour ago may not be there anymore. The BPEL engine performance statistics only includes latencies. It does not provide throughputs. Fortunately, Oracle SOA Suite runs with the SOA Infrastructure database and a lot of performance data are naturally persisted there. It is at a more coarse grain than the in-memory BPEL Statistics, but it does have its own strengths as it is persisted. Here I would like offer examples of some basic SQL queries you can run against the infrastructure database of Oracle SOA Suite 11G to acquire the performance statistics for a given period of time. You can run it immediately after you modify the date range to match your actual system. 1. Asynchronous/one-way messages incoming rates The following query will show number of messages sent to one-way/async BPEL processes during a given time period, organized by process names and states select composite_name composite, state, count(*) Count from dlv_message where receive_date >= to_timestamp('2012-10-24 21:00:00','YYYY-MM-DD HH24:MI:SS') and receive_date <= to_timestamp('2012-10-24 21:59:59','YYYY-MM-DD HH24:MI:SS') group by composite_name, state order by Count; 2. Throughput of BPEL process instances The following query shows the number of synchronous and asynchronous process instances created during a given time period. It list instances of all states, including the unfinished and faulted ones. The results will include all composites cross all SOA partitions select state, count(*) Count, composite_name composite, component_name,componenttype from cube_instance where creation_date >= to_timestamp('2012-10-24 21:00:00','YYYY-MM-DD HH24:MI:SS') and creation_date <= to_timestamp('2012-10-24 21:59:59','YYYY-MM-DD HH24:MI:SS') group by composite_name, component_name, componenttype order by count(*) desc; 3. Throughput and latencies of BPEL process instances This query is augmented on the previous one, providing more comprehensive information. It gives not only throughput but also the maximum, minimum and average elapse time BPEL process instances. select composite_name Composite, component_name Process, componenttype, state, count(*) Count, trunc(Max(extract(day from (modify_date-creation_date))*24*60*60 + extract(hour from (modify_date-creation_date))*60*60 + extract(minute from (modify_date-creation_date))*60 + extract(second from (modify_date-creation_date))),4) MaxTime, trunc(Min(extract(day from (modify_date-creation_date))*24*60*60 + extract(hour from (modify_date-creation_date))*60*60 + extract(minute from (modify_date-creation_date))*60 + extract(second from (modify_date-creation_date))),4) MinTime, trunc(AVG(extract(day from (modify_date-creation_date))*24*60*60 + extract(hour from (modify_date-creation_date))*60*60 + extract(minute from (modify_date-creation_date))*60 + extract(second from (modify_date-creation_date))),4) AvgTime from cube_instance where creation_date >= to_timestamp('2012-10-24 21:00:00','YYYY-MM-DD HH24:MI:SS') and creation_date <= to_timestamp('2012-10-24 21:59:59','YYYY-MM-DD HH24:MI:SS') group by composite_name, component_name, componenttype, state order by count(*) desc;   4. Combine all together Now let's combine all of these 3 queries together, and parameterize the start and end time stamps to make the script a bit more robust. The following script will prompt for the start and end time before querying against the database: accept startTime prompt 'Enter start time (YYYY-MM-DD HH24:MI:SS)' accept endTime prompt 'Enter end time (YYYY-MM-DD HH24:MI:SS)' Prompt "==== Rejected Messages ===="; REM 2012-10-24 21:00:00 REM 2012-10-24 21:59:59 select count(*), composite_dn from rejected_message where created_time >= to_timestamp('&&StartTime','YYYY-MM-DD HH24:MI:SS') and created_time <= to_timestamp('&&EndTime','YYYY-MM-DD HH24:MI:SS') group by composite_dn; Prompt " "; Prompt "==== Throughput of one-way/asynchronous messages ===="; select state, count(*) Count, composite_name composite from dlv_message where receive_date >= to_timestamp('&StartTime','YYYY-MM-DD HH24:MI:SS') and receive_date <= to_timestamp('&EndTime','YYYY-MM-DD HH24:MI:SS') group by composite_name, state order by Count; Prompt " "; Prompt "==== Throughput and latency of BPEL process instances ====" select state, count(*) Count, trunc(Max(extract(day from (modify_date-creation_date))*24*60*60 + extract(hour from (modify_date-creation_date))*60*60 + extract(minute from (modify_date-creation_date))*60 + extract(second from (modify_date-creation_date))),4) MaxTime, trunc(Min(extract(day from (modify_date-creation_date))*24*60*60 + extract(hour from (modify_date-creation_date))*60*60 + extract(minute from (modify_date-creation_date))*60 + extract(second from (modify_date-creation_date))),4) MinTime, trunc(AVG(extract(day from (modify_date-creation_date))*24*60*60 + extract(hour from (modify_date-creation_date))*60*60 + extract(minute from (modify_date-creation_date))*60 + extract(second from (modify_date-creation_date))),4) AvgTime, composite_name Composite, component_name Process, componenttype from cube_instance where creation_date >= to_timestamp('&StartTime','YYYY-MM-DD HH24:MI:SS') and creation_date <= to_timestamp('&EndTime','YYYY-MM-DD HH24:MI:SS') group by composite_name, component_name, componenttype, state order by count(*) desc;  

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  • Performance tuning of tabular data models in Analysis Services

    - by Greg Low
    More and more practical information around working with tabular data models is starting to appear as more and more sites get deployed.At SQL Down Under, we've already helped quite a few customers move to tabular data models in Analysis Services and have started to collect quite a bit of information on what works well (and what doesn't) in terms of performance of these models. We've also been running a lot of training on tabular data models.It was great to see a whitepaper on the performance of these models released today.Performance Tuning of Tabular Models in SQL Server 2012 Analysis Services was written by John Sirmon, Greg Galloway, Cindy Gross and Karan Gulati. You'll find it here: http://msdn.microsoft.com/en-us/library/dn393915.aspx

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  • Gartner: Magic Quadrant for Corporate Performance Management Suites, 2012

    - by Mike.Hallett(at)Oracle-BI&EPM
    Hyperion clearly leads the pack again in Gartner’s analysis of the CPM / EPM market, saying; “Oracle is a Leader in CPM suites, with one of the most widely distributed solutions in the market. Oracle Hyperion Enterprise Performance Management is recognized by CFOs worldwide. The vendor has a well-established partner channel, with both large and smaller CPM SI specialists. Hyperion skills are also plentiful among the independent consultant community, given the well-established products. “ “Oracle continues to innovate, bringing incremental improvements across the portfolio as well as new financial close management, disclosure management and predictive planning additions. Furthermore, Oracle has improved integration of Hyperion with the Oracle BI platform, and has improved planning performance, enabling Hyperion Planning to use Oracle Exalytics In-Memory Machine.” For the full article see here: Gartner: Magic Quadrant for Corporate Performance Management Suites, 2012 And if you missed it, here is also the MQ for BI: Gartner: Magic Quadrant for Business Intelligence Platforms, 2012

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  • Common Javascript mistakes that severely affect performance?

    - by melee
    At a recent UI/UX MeetUp that I attended, I gave some feedback on a website that used Javascript (jQuery) for its interaction and UI - it was fairly simple animations and manipulation, but the performance on a decent computer was horrific. It actually reminded me of a lot of sites/programs that I've seen with the same issue, where certain actions just absolutely destroy performance. It is mostly in (or at least more noticeable in) situations where Javascript is almost serving as a Flash replacement. This is in stark contrast to some of the webapps that I have used that have far more Javascript and functionality but run very smoothly (COGNOS by IBM is one I can think of off the top of my head). I'd love to know some of the common issues that aren't considered when developing JS that will kill the performance of the site.

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  • Maximize Performance and Availability with Oracle Data Integration

    - by Tanu Sood
    Normal 0 false false false EN-US X-NONE X-NONE /* 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-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif"; mso-fareast-font-family:Calibri; mso-bidi-font-family:"Times New Roman";} Alert: Oracle is hosting the 12c Launch Webcast for Oracle Data Integration and Oracle Golden Gate on Tuesday, November 12 (tomorrow) to discuss the new capabilities in detail and share customer perspectives. Hear directly from customer experts and executives from SolarWorld Industries America, British Telecom and Rittman Mead and get your questions answered live by product experts. Register for this complimentary webcast today and join in the discussion tomorrow. Author: Irem Radzik, Senior Principal Product Director, Oracle Organizations that want to use IT as a strategic point of differentiation prefer Oracle’s complete application offering to drive better business performance and optimize their IT investments. These enterprise applications are in the center of business operations and they contain critical data that needs to be accessed continuously, as well as analyzed and acted upon in a timely manner. These systems also need to operate with high-performance and availability, which means analytical functions should not degrade applications performance, and even system maintenance and upgrades should not interrupt availability. Oracle’s data integration products, Oracle Data Integrator, Oracle GoldenGate, and Oracle Enterprise Data Quality, provide the core foundation for bringing data from various business-critical systems to gain a broader, unified view. As a more advance offering to 3rd party products, Oracle’s data integration products facilitate real-time reporting for Oracle Applications without impacting application performance, and provide ability to upgrade and maintain the system without taking downtime. Oracle GoldenGate is certified for Oracle Applications, including E-Business Suite, Siebel CRM, PeopleSoft, and JD Edwards, for moving transactional data in real-time to a dedicated operational reporting environment. This solution allows the app users to offload the resource-heavy queries to the reporting instance(s), reducing CPU utilization, improving OLTP performance, and extending the lifetime of existing IT assets. In addition, having a dedicated reporting instance with up-to-the-second transactional data allows optimizing the reporting environment and even decreasing costs as GoldenGate can move only the required data from expensive mainframe environments to cost-efficient open system platforms.  With real-time data replication capabilities GoldenGate is also certified to enable application upgrades and database/hardware/OS migration without impacting business operations. GoldenGate is certified for Siebel CRM, Communications Billing and Revenue Management and JD Edwards for supporting zero downtime upgrades to the latest app version. GoldenGate synchronizes a parallel, upgraded system with the old version in real time, thus enables continuous operations during the process. Oracle GoldenGate is also certified for minimal downtime database migrations for Oracle E-Business Suite and other key applications. GoldenGate’s solution also minimizes the risk by offering a failback option after the switchover to the new environment. Furthermore, Oracle GoldenGate’s bidirectional active-active data replication is certified for Oracle ATG Web Commerce to enable geographically load balancing and high availability for ATG customers. For enabling better business insight, Oracle Data Integration products power Oracle BI Applications with high performance bulk and real-time data integration. Oracle Data Integrator (ODI) is embedded in Oracle BI Applications version 11.1.1.7.1 and helps to integrate data end-to-end across the full BI Applications architecture, supporting capabilities such as data-lineage, which helps business users identify report-to-source capabilities. ODI is integrated with Oracle GoldenGate and provides Oracle BI Applications customers the option to use real-time transactional data in analytics, and do so non-intrusively. By using Oracle GoldenGate with the latest release of Oracle BI Applications, organizations not only leverage fresh data in analytics, but also eliminate the need for an ETL batch window and minimize the impact on OLTP systems. You can learn more about Oracle Data Integration products latest 12c version in our upcoming launch webcast and access the app-specific free resources in the new Data Integration for Oracle Applications Resource Center.

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  • The convergence of Risk and Performance Management

    Historically, the market has viewed Enterprise Performance Management (EPM) and Governance, Risk and Compliance (GRC) as separate processes and solutions. But these two worlds are coming together – in fact industry analyst firms such as AMR Research believe that by the end of 2009, risk management will be part of every EPM discussion. Tune into this conversation with John O'Rourke, VP of Product Marketing for Oracle Enterprise Performance Management Solutions, and Karen dela Torre, Senior Director of Product Marketing for Financial Applications to learn how EPM and GRC are converging, what the integration points are, and what Oracle is doing to help customers perform more effective risk and performance management.

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  • How to recognize my performance plateau?

    - by Dat Chu
    Performance plateau happens right after one becomes "adequately" proficient at a certain task. e.g. You learn a new language/framework/technology. You become better progressively. Then all of the sudden you realize that you have spent quite some time on this technology and you are not getting better at it. As a programmer who is conscious about my performance/knowledge/skill, how do I detect when I am in a performance plateau? What can I do to jump out of it (and keep going upward)?

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  • Understanding the 'High Performance' meaning in Extreme Transaction Processing

    - by kyap
    Despite my previous blogs entries on SOA/BPM and Identity Management, the domain where I'm the most passionated is definitely the Extreme Transaction Processing, commonly called XTP.I came across XTP back to 2007 while I was still FMW Product Manager in EMEA. At that time Oracle acquired a company called Tangosol, which owned an unique product called Coherence that we renamed to Oracle Coherence. Beside this innovative renaming of the product, to be honest, I didn't know much about it, except being a "distributed in-memory cache for Extreme Transaction Processing"... not very helpful still.In general when people doesn't fully understand a technology or a concept, they tend to find some shortcuts, either correct or not, to justify their lack-of understanding... and of course I was part of this category of individuals. And the shortcut was "Oracle Coherence Cache helps to improve Performance". Excellent marketing slogan... but not very meaningful still. By chance I was able to get away quickly from that group in July 2007* at Thames Valley Park (UK), after I attended one of the most interesting workshops, in my 10 years career in Oracle, delivered by Brian Oliver. The biggest mistake I made was to assume that performance improvement with Coherence was related to the response time. Which can be considered as legitimus at that time, because after-all caches help to reduce latency on cached data access, hence reduce the response-time. But like all caches, you need to define caching and expiration policies, thinking about the cache-missed strategy, and most of the time you have to re-write partially your application in order to work with the cache. At a result, the expected benefit vanishes... so, not very useful then?The key mistake I made was my perception or obsession on how performance improvement should be driven, but I strongly believe this is still a common problem to most of the developers. In fact we all know the that the performance of a system is generally presented by the Capacity (or Throughput), with the 2 important dimensions Speed (response-time) and Volume (load) :Capacity (TPS) = Volume (T) / Speed (S)To increase the Capacity, we can either reduce the Speed(in terms of response-time), or to increase the Volume. However we tend to only focus on reducing the Speed dimension, perhaps it is more concrete and tangible to measure, and nicer to present to our management because there's a direct impact onto the end-users experience. On the other hand, we assume the Volume can be addressed by the underlying hardware or software stack, so if we need more capacity (scale out), we just add more hardware or software. Unfortunately, the reality proves that IT is never as ideal as we assume...The challenge with Speed improvement approach is that it is generally difficult and costly to make things already fast... faster. And by adding Coherence will not necessarily help either. Even though we manage to do so, the Capacity can not increase forever because... the Speed can be influenced by the Volume. For all system, we always have a performance illustration as follow: In all traditional system, the increase of Volume (Transaction) will also increase the Speed (Response-Time) as some point. The reason is simple: most of the time the Application logics were not designed to scale. As an example, if you have a while-loop in your application, it is natural to conceive that parsing 200 entries will require double execution-time compared to 100 entries. If you need to "Speed-up" the execution, you can only upgrade your hardware (scale-up) with faster CPU and/or network to reduce network latency. It is technically limited and economically inefficient. And this is exactly where XTP and Coherence kick in. The primary objective of XTP is about designing applications which can scale-out for increasing the Volume, by applying coding techniques to keep the execution-time as constant as possible, independently of the number of runtime data being manipulated. It is actually not just about having an application running as fast as possible, but about having a much more predictable system, with constant response-time and linearly scale, so we can easily increase throughput by adding more hardwares in parallel. It is in general combined with the Low Latency Programming model, where we tried to optimize the network usage as much as possible, either from the programmatic angle (less network-hoops to complete a task), and/or from a hardware angle (faster network equipments). In this picture, Oracle Coherence can be considered as software-level XTP enabler, via the Distributed-Cache because it can guarantee: - Constant Data Objects access time, independently from the number of Objects and the Coherence Cluster size - Data Objects Distribution by Affinity for in-memory data grouping - In-place Data Processing for parallel executionTo summarize, Oracle Coherence is indeed useful to improve your application performance, just not in the way we commonly think. It's not about the Speed itself, but about the overall Capacity with Extreme Load while keeping consistant Speed. In the future I will keep adding new blog entries around this topic, with some sample codes experiences sharing that I capture in the last few years. In the meanwhile if you want to know more how Oracle Coherence, I strongly suggest you to start with checking how our worldwide customers are using Oracle Coherence first, then you can start playing with the product through our tutorial.Have Fun !

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  • Google I/O 2010 - Architecting for performance with GWT

    Google I/O 2010 - Architecting for performance with GWT Google I/O 2010 - Architecting for performance with GWT GWT 201 Joel Webber, Adam Schuck Modern web applications are quickly evolving to an architecture that has to account for the performance characteristics of the client, the server, and the global network connecting them. Should you render HTML on the server or build DOM structures with JS in the browser, or both? This session discusses this, as well as several other key architectural considerations to keep in mind when building your Next Big Thing. For all I/O 2010 sessions, please go to code.google.com From: GoogleDevelopers Views: 9 1 ratings Time: 01:01:09 More in Science & Technology

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  • The Convergence of Risk and Performance Management

    Historically, the market has viewed Enterprise Performance Management (EPM) and Governance, Risk and Compliance (GRC) as separate processes and solutions. But these two worlds are coming together-in fact industry analyst firms such as AMR Research believe that by the end of 2009, risk management will be part of every EPM discussion. Tune into this conversation with John O'Rourke, VP of Product Marketing for Oracle Enterprise Performance Management Solutions, and Karen dela Torre, Senior Director of Product Marketing for Financial Applications to learn how EPM and GRC are converging, what the integration points are, and what Oracle is doing to help customers perform more effective risk and performance management.

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  • ASP.NET Performance Framework

    At the start of the year, I finished a 5 part series on ASP.NET performance - focusing on largely generic ways to improve website performance rather than specific ASP.NET performance tricks. The series focused on a number of topics, including merging and shrinking files, using modules to remove unecessary headers and setting caching headers, enabling cache busting and automatically generating cache busted referneces in css, as well as an introduction to nginx. Yesterday I managed to put a number...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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  • Problem with RAID5 (mdadm) - disk detached

    - by poscaman
    Having these lines in /var/log/syslog Apr 18 16:53:05 Server kernel: [4487878.816036] ata4: EH in SWNCQ mode,QC:qc_active 0x1 sactive 0x1 Apr 18 16:53:05 Server kernel: [4487878.816058] ata4: SWNCQ:qc_active 0x1 defer_bits 0x0 last_issue_tag 0x0 Apr 18 16:53:05 Server kernel: [4487878.816059] dhfis 0x1 dmafis 0x1 sdbfis 0x0 Apr 18 16:53:05 Server kernel: [4487878.816093] ata4: ATA_REG 0x40 ERR_REG 0x0 Apr 18 16:53:05 Server kernel: [4487878.816108] ata4: tag : dhfis dmafis sdbfis sacitve Apr 18 16:53:05 Server kernel: [4487878.816125] ata4: tag 0x0: 1 1 0 1 Apr 18 16:53:05 Server kernel: [4487878.816150] ata4.00: exception Emask 0x0 SAct 0x1 SErr 0x0 action 0x6 frozen Apr 18 16:53:05 Server kernel: [4487878.816178] ata4.00: failed command: WRITE FPDMA QUEUED Apr 18 16:53:05 Server kernel: [4487878.816199] ata4.00: cmd 61/08:00:00:88:e0/00:00:e8:00:00/40 tag 0 ncq 4096 out Apr 18 16:53:05 Server kernel: [4487878.816200] res 40/00:00:01:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout) Apr 18 16:53:05 Server kernel: [4487878.816253] ata4.00: status: { DRDY } Apr 18 16:53:05 Server kernel: [4487878.816272] ata4: hard resetting link Apr 18 16:53:05 Server kernel: [4487878.816274] ata4: nv: skipping hardreset on occupied port Apr 18 16:53:06 Server kernel: [4487879.676029] ata4: SATA link up 3.0 Gbps (SStatus 123 SControl 300) Apr 18 16:53:07 Server kernel: [4487880.416749] ata4.00: n_sectors mismatch 3907029168 != 268435455 Apr 18 16:53:07 Server kernel: [4487880.416752] ata4.00: revalidation failed (errno=-19) Apr 18 16:53:07 Server kernel: [4487880.416773] ata4.00: limiting speed to UDMA/133:PIO2 Apr 18 16:53:11 Server kernel: [4487884.676024] ata4: hard resetting link Apr 18 16:53:11 Server kernel: [4487884.676027] ata4: nv: skipping hardreset on occupied port Apr 18 16:53:12 Server kernel: [4487885.144032] ata4: SATA link up 3.0 Gbps (SStatus 123 SControl 300) Apr 18 16:53:12 Server kernel: [4487885.240185] ata4.00: failed to IDENTIFY (INIT_DEV_PARAMS failed, err_mask=0x80) Apr 18 16:53:12 Server kernel: [4487885.240190] ata4.00: revalidation failed (errno=-5) Apr 18 16:53:12 Server kernel: [4487885.240210] ata4.00: disabled Apr 18 16:53:17 Server kernel: [4487890.144023] ata4: hard resetting link Apr 18 16:53:17 Server kernel: [4487891.024033] ata4: SATA link up 3.0 Gbps (SStatus 123 SControl 300) Apr 18 16:53:17 Server kernel: [4487891.033357] ata4.00: ATA-8: WDC WD20EARS-00S8B1, 80.00A80, max UDMA/133 Apr 18 16:53:17 Server kernel: [4487891.033360] ata4.00: 3907029168 sectors, multi 1: LBA48 NCQ (depth 31/32) Apr 18 16:53:17 Server kernel: [4487891.048347] ata4.00: configured for UDMA/133 Apr 18 16:53:17 Server kernel: [4487891.048361] sd 3:0:0:0: [sdc] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE Apr 18 16:53:17 Server kernel: [4487891.048365] sd 3:0:0:0: [sdc] Sense Key : Aborted Command [current] [descriptor] Apr 18 16:53:17 Server kernel: [4487891.048369] Descriptor sense data with sense descriptors (in hex): Apr 18 16:53:17 Server kernel: [4487891.048371] 72 0b 00 00 00 00 00 0c 00 0a 80 00 00 00 00 00 Apr 18 16:53:17 Server kernel: [4487891.048378] 00 00 00 00 Apr 18 16:53:17 Server kernel: [4487891.048382] sd 3:0:0:0: [sdc] Add. Sense: No additional sense information Apr 18 16:53:17 Server kernel: [4487891.048385] sd 3:0:0:0: [sdc] CDB: Write(10): 2a 00 e8 e0 88 00 00 00 08 00 Apr 18 16:53:17 Server kernel: [4487891.048393] end_request: I/O error, dev sdc, sector 3907028992 Apr 18 16:53:17 Server kernel: [4487891.048420] sd 3:0:0:0: rejecting I/O to offline device Apr 18 16:53:17 Server kernel: [4487891.048440] sd 3:0:0:0: rejecting I/O to offline device Apr 18 16:53:17 Server kernel: [4487891.048458] end_request: I/O error, dev sdc, sector 3907028992 Apr 18 16:53:17 Server kernel: [4487891.048477] md: super_written gets error=-5, uptodate=0 Apr 18 16:53:17 Server kernel: [4487891.048482] raid5: Disk failure on sdc, disabling device. Apr 18 16:53:17 Server kernel: [4487891.048483] raid5: Operation continuing on 3 devices. Apr 18 16:53:17 Server kernel: [4487891.048525] ata4: EH complete Apr 18 16:53:17 Server kernel: [4487891.048554] sd 3:0:0:0: rejecting I/O to offline device Apr 18 16:53:17 Server kernel: [4487891.048576] sd 3:0:0:0: rejecting I/O to offline device Apr 18 16:53:17 Server kernel: [4487891.048596] sd 3:0:0:0: rejecting I/O to offline device Apr 18 16:53:17 Server kernel: [4487891.048615] sd 3:0:0:0: [sdc] READ CAPACITY(16) failed Apr 18 16:53:17 Server kernel: [4487891.048617] sd 3:0:0:0: [sdc] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK Apr 18 16:53:17 Server kernel: [4487891.048620] sd 3:0:0:0: [sdc] Sense not available. Apr 18 16:53:17 Server kernel: [4487891.048624] sd 3:0:0:0: rejecting I/O to offline device Apr 18 16:53:17 Server kernel: [4487891.048643] sd 3:0:0:0: rejecting I/O to offline device Apr 18 16:53:17 Server kernel: [4487891.048663] sd 3:0:0:0: rejecting I/O to offline device Apr 18 16:53:17 Server kernel: [4487891.048681] sd 3:0:0:0: [sdc] READ CAPACITY failed Apr 18 16:53:17 Server kernel: [4487891.048683] sd 3:0:0:0: [sdc] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK Apr 18 16:53:17 Server kernel: [4487891.048685] sd 3:0:0:0: [sdc] Sense not available. Apr 18 16:53:17 Server kernel: [4487891.048689] sd 3:0:0:0: rejecting I/O to offline device Apr 18 16:53:17 Server kernel: [4487891.048709] sd 3:0:0:0: rejecting I/O to offline device Apr 18 16:53:17 Server kernel: [4487891.048800] sd 3:0:0:0: rejecting I/O to offline device Apr 18 16:53:17 Server kernel: [4487891.048860] sd 3:0:0:0: rejecting I/O to offline device Apr 18 16:53:17 Server kernel: [4487891.049028] sd 3:0:0:0: [sdc] Asking for cache data failed Apr 18 16:53:17 Server kernel: [4487891.049048] sd 3:0:0:0: [sdc] Assuming drive cache: write through Apr 18 16:53:17 Server kernel: [4487891.049071] sdc: detected capacity change from 2000398934016 to 0 Apr 18 16:53:17 Server kernel: [4487891.049080] ata4.00: detaching (SCSI 3:0:0:0) Apr 18 16:53:18 Server kernel: [4487891.061149] sd 3:0:0:0: [sdc] Stopping disk Apr 18 16:53:18 Server kernel: [4487891.485492] RAID5 conf printout: Apr 18 16:53:18 Server kernel: [4487891.485496] --- rd:4 wd:3 Apr 18 16:53:18 Server kernel: [4487891.485500] disk 0, o:1, dev:sdb Apr 18 16:53:18 Server kernel: [4487891.485502] disk 1, o:0, dev:sdc Apr 18 16:53:18 Server kernel: [4487891.485504] disk 2, o:1, dev:sdd Apr 18 16:53:18 Server kernel: [4487891.485506] disk 3, o:1, dev:sde Apr 18 16:53:18 Server kernel: [4487891.497014] RAID5 conf printout: Apr 18 16:53:18 Server kernel: [4487891.497016] --- rd:4 wd:3 Apr 18 16:53:18 Server kernel: [4487891.497018] disk 0, o:1, dev:sdb Apr 18 16:53:18 Server kernel: [4487891.497019] disk 2, o:1, dev:sdd Apr 18 16:53:18 Server kernel: [4487891.497021] disk 3, o:1, dev:sde Apr 18 16:53:18 Server kernel: [4487891.838719] scsi 3:0:0:0: Direct-Access ATA WDC WD20EARS-00S 80.0 PQ: 0 ANSI: 5 Apr 18 16:53:18 Server kernel: [4487891.838886] sd 3:0:0:0: Attached scsi generic sg3 type 0 Apr 18 16:53:18 Server kernel: [4487891.838911] sd 3:0:0:0: [sdf] 3907029168 512-byte logical blocks: (2.00 TB/1.81 TiB) Apr 18 16:53:18 Server kernel: [4487891.838964] sd 3:0:0:0: [sdf] Write Protect is off Apr 18 16:53:18 Server kernel: [4487891.838967] sd 3:0:0:0: [sdf] Mode Sense: 00 3a 00 00 Apr 18 16:53:18 Server kernel: [4487891.838988] sd 3:0:0:0: [sdf] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA Apr 18 16:53:20 Server kernel: [4487891.839147] sdf: unknown partition table Apr 18 16:53:20 Server kernel: [4487893.130026] sd 3:0:0:0: [sdf] Attached SCSI disk Right now, i'm unable to do anything on /dev/sdc. Is there any way to try to re-attach it? I don't want to power-down the server unless absolutely necessary System: Debian Stable 2.6.32-5-amd64 mdadm version 3.1.4-1+8efb9d1 cat /proc/mdstat Personalities : [raid6] [raid5] [raid4] md0 : active raid5 sdb[0] sdc[4](F) sde[3] sdd[2] 5860543488 blocks level 5, 64k chunk, algorithm 2 [4/3] [U_UU] unused devices: <none> mdadm --examine --scan ARRAY /dev/md0 UUID=1a7744b5:912ec7af:f82a9565:e3b453b4

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