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• How do you re-mount an ext3 fs readwrite after it gets mounted readonly from a disk error?

  - by cagenut

  Its a relatively common problem when something goes wrong in a SAN for ext3 to detect the disk write errors and remount the filesystem read-only. Thats all well and good, only when the SAN is fixed I can't figure out how to re-re-mount the filesystem read-write without rebooting. Behold: [root@localhost ~]# multipath -ll mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=1 queue_if_no_path][hwhandler=0][rw] \_ round-robin 0 [prio=2][active] \_ 1:0:0:1 sdb 8:16 [active][ready] \_ 2:0:0:1 sdc 8:32 [active][ready] [root@localhost ~]# mount /dev/mapper/mpath0 /mnt/foo [root@localhost ~]# touch /mnt/foo/blah All good, now I yank the LUN out from under it. [root@localhost ~]# touch /mnt/foo/blah [root@localhost ~]# touch /mnt/foo/blah touch: cannot touch `/mnt/foo/blah': Read-only file system [root@localhost ~]# tail /var/log/messages Mar 18 13:17:33 localhost multipathd: sdb: tur checker reports path is down Mar 18 13:17:34 localhost multipathd: sdc: tur checker reports path is down Mar 18 13:17:35 localhost kernel: Aborting journal on device dm-2. Mar 18 13:17:35 localhost kernel: Buffer I/O error on device dm-2, logical block 1545 Mar 18 13:17:35 localhost kernel: lost page write due to I/O error on dm-2 Mar 18 13:17:36 localhost kernel: ext3_abort called. Mar 18 13:17:36 localhost kernel: EXT3-fs error (device dm-2): ext3_journal_start_sb: Detected aborted journal Mar 18 13:17:36 localhost kernel: Remounting filesystem read-only It only thinks its read-only, in reality its not even there. [root@localhost ~]# multipath -ll sdb: checker msg is "tur checker reports path is down" sdc: checker msg is "tur checker reports path is down" mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=0][hwhandler=0][rw] \_ round-robin 0 [prio=0][enabled] \_ 1:0:0:1 sdb 8:16 [failed][faulty] \_ 2:0:0:1 sdc 8:32 [failed][faulty] [root@localhost ~]# ll /mnt/foo/ ls: reading directory /mnt/foo/: Input/output error total 20 -rw-r--r-- 1 root root 0 Mar 18 13:11 bar How it still remembers that 'bar' file being there... mystery, but not important right now. Now I re-present the LUN: [root@localhost ~]# tail /var/log/messages Mar 18 13:23:58 localhost multipathd: sdb: tur checker reports path is up Mar 18 13:23:58 localhost multipathd: 8:16: reinstated Mar 18 13:23:58 localhost multipathd: mpath0: queue_if_no_path enabled Mar 18 13:23:58 localhost multipathd: mpath0: Recovered to normal mode Mar 18 13:23:58 localhost multipathd: mpath0: remaining active paths: 1 Mar 18 13:23:58 localhost multipathd: dm-2: add map (uevent) Mar 18 13:23:58 localhost multipathd: dm-2: devmap already registered Mar 18 13:23:59 localhost multipathd: sdc: tur checker reports path is up Mar 18 13:23:59 localhost multipathd: 8:32: reinstated Mar 18 13:23:59 localhost multipathd: mpath0: remaining active paths: 2 Mar 18 13:23:59 localhost multipathd: dm-2: add map (uevent) Mar 18 13:23:59 localhost multipathd: dm-2: devmap already registered [root@localhost ~]# multipath -ll mpath0 (36001f93000a310000299000200000000) dm-2 XIOTECH,ISE1400 [size=1.1T][features=1 queue_if_no_path][hwhandler=0][rw] \_ round-robin 0 [prio=2][enabled] \_ 1:0:0:1 sdb 8:16 [active][ready] \_ 2:0:0:1 sdc 8:32 [active][ready] Great right? It says [rw] right there. Not so fast: [root@localhost ~]# touch /mnt/foo/blah touch: cannot touch `/mnt/foo/blah': Read-only file system OK, doesn't do it automatically, I'll just give it a little push: [root@localhost ~]# mount -o remount /mnt/foo mount: block device /dev/mapper/mpath0 is write-protected, mounting read-only Noooooooooo. I have tried all sorts of different mount/tune2fs/dmsetup commands and I cannot figure out how to get it to un-flag the block device as write-protected. Rebooting will fix it, but I'd much rather do it on-line. An hour of googling has gotten me nowhere either. Save me ServerFault.

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• Windows folder has readonly attribute that cannot be removed

  - by drasto

  I have a zip file containing Eclipse workspace. When I unzip it all the extracted folders have read only attribute set to true. When I uncheck "read only" in properties dialog and click apply the attribute seems to be removed. But when I reopen properties dialog it is there again. Eclipse will not accept folder that is read only as a workspace. I need it to be removed. Some points I'd like to make: Only folders have read only attribute, files don't. I use Windows 7, for unzipping I have used 7zip. I have tryied to remove the attribute from command line like this: attrib -r -s c:\pathToFolder. It did not work.

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• How do I prevent Excel from locking files by default?

  - by Andrzej Doyle

  When I double-click on a CSV file on a network share, the file is opened in Microsoft Excel (which is what I want). However, Excel assumes that I'm going to modify the file, and that everyone else is too, and so puts a lock on it. In practice I very rarely actually want to modify these files, merely read from them. And if I have the file open in an Excel window in the background, it stops anyone else from opening the same file. I am aware that I can manually open a file as read-only from the File - Open dialog within Excel. However I almost always open files by double-clicking on them in Explorer (or Outlook, for attachments). Is it possible to change the file association so that the default handler for CSV files is "Excel in read-only mode"? Is there a command-line argument that I can use in the Open With... dialog to achieve this? Or more bluntly - when I am looking at a CSV file in Windows Explorer, is there an easier way to open it read-only than starting up Excel myself, selecting File - Open, choosing "read only" from the dropdown, manually navigating to the same folder in the hierarchy, and then opening the file? (I am happy to have to jump through hoops on the rare occasions that I want to modify and save a file.)

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• Frequent change of file-system to read-only

  - by Anuj

  I am using Ubuntu 12.04 on my relatively new laptop. Initial few days, everything worked fine, but then suddenly I started getting a strange problem. After every 2-3 days, the file-system was becoming read-only. I was unable to save/download anything in the installation drive and the system hanged if I attempted to do so, after which I needed to force restart. I had to run fsck in the repair mode to get it fixed (temporarily). There I used to get the following messages: "Inodes that were part of a corrupted orphan linked list found. UNEXPECTED INCONSISTENCY: RUN FSCK MANUALLY. fsck / [886] terminated with status 4. Filesystem has errors: /" Then it stopped here and I had to restart again, after which it asked whether I want to repair or not, then the system ran properly. After a day or 2, again I used to face exactly the same problem. The problem become more frequent in the last few days, and even after running the fsck and restarting, was not solving the problem. I re-installed the OS a couple of days back, but even after that, the problem exists. Though it is not that frequent now, but still at times, the file-system becomes read-only and the system stops behaving normally, and I have to run fsck in the repair mode, which makes the whole thing normal. Yes I keep my laptop switched on for long hours and it does get heated up. Please help. Thanks, Anuj

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• Accessing ADF Faces components that are read-only from JavaScript

  - by Frank Nimphius

  Almost as a note to myself and to justify the time I spent on analyzing aproblem, a quick note on what to watch out for when working trying to access read-only ADF Faces components from JavaScript.  Those who tried JavaScript in ADF Faces probably know that you need to ensure the ADF Faces component  is represented by a JavaScript object on the client. You do this either implicitly by adding an af:clientListener component (in case you want to listen for a component event) or explicitly by setting the ADF Faces component clientComponent property to true. For the use case I looked at in JDeveloper 11g R1 (11.1.1.7) I needed to make an output text component clickable to call a JavaScript function in response. Though I added the af:clientComponent tag to the component I recognized that it also needed the clientComponent property set to true. Though I remember this as not being required in 11.1.1.6, I like the new behavior as it helps preventing read-only components from firing client side events unless you tell it to do so by setting the clientComponent property to true. Note: As the time of writing, JDeveloper 11.1.1.7 is not publicly available and I put the note in this blog as a reminder in case you ever hit a similar challenge so you know what to do.

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• Ubuntu boots in read-only filesystem after upgrade!

  - by akatzbreaker

  I got a serious problem here: I recently upgraded to the Latest Version of Ubuntu. Now, I boot to my Ubuntu Partition, and I get a Low-Graphics error! I boot to a Recovery-Mode to see what the Problem is. Then, I try to Fix any Damaged Packages, to run fsck but nothing solved the Problem. Then, from the Recovery Menu, I open a Root Shell. I try to create a File and I understand that the Filesystem is Read-Only. Then, I run: mount -o remount,rw / and it Worked for that Terminal Session! When I go back to recovery, I select to resume Boot Normally but I get the Same Error! a I also tried to Boot to my Root Shell again, remount as Read-Write and Start Gnome from there. It Worked! (But the user is ROOT, and is quite Dangerous!) However, I can't do all this proccess at every boot! Any Solution? (Note that when I try to create a new File in my Ubuntu Partition from another OS, I don't get any Errors!)

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• Read XML Files using LINQ to XML and Extension Methods

  - by psheriff

  In previous blog posts I have discussed how to use XML files to store data in your applications. I showed you how to read those XML files from your project and get XML from a WCF service. One of the problems with reading XML files is when elements or attributes are missing. If you try to read that missing data, then a null value is returned. This can cause a problem if you are trying to load that data into an object and a null is read. This blog post will show you how to create extension methods to detect null values and return valid values to load into your object. The XML Data An XML data file called Product.xml is located in the \Xml folder of the Silverlight sample project for this blog post. This XML file contains several rows of product data that will be used in each of the samples for this post. Each row has 4 attributes; namely ProductId, ProductName, IntroductionDate and Price. <Products>  <Product ProductId="1"           ProductName="Haystack Code Generator for .NET"           IntroductionDate="07/01/2010"  Price="799" />  <Product ProductId="2"           ProductName="ASP.Net Jumpstart Samples"           IntroductionDate="05/24/2005"  Price="0" />  ...  ...</Products> The Product Class Just as you create an Entity class to map each column in a table to a property in a class, you should do the same for an XML file too. In this case you will create a Product class with properties for each of the attributes in each element of product data. The following code listing shows the Product class. public class Product : CommonBase{  public const string XmlFile = @"Xml/Product.xml";   private string _ProductName;  private int _ProductId;  private DateTime _IntroductionDate;  private decimal _Price;   public string ProductName  {    get { return _ProductName; }    set {      if (_ProductName != value) {        _ProductName = value;        RaisePropertyChanged("ProductName");      }    }  }   public int ProductId  {    get { return _ProductId; }    set {      if (_ProductId != value) {        _ProductId = value;        RaisePropertyChanged("ProductId");      }    }  }   public DateTime IntroductionDate  {    get { return _IntroductionDate; }    set {      if (_IntroductionDate != value) {        _IntroductionDate = value;        RaisePropertyChanged("IntroductionDate");      }    }  }   public decimal Price  {    get { return _Price; }    set {      if (_Price != value) {        _Price = value;        RaisePropertyChanged("Price");      }    }  }} NOTE: The CommonBase class that the Product class inherits from simply implements the INotifyPropertyChanged event in order to inform your XAML UI of any property changes. You can see this class in the sample you download for this blog post. Reading Data When using LINQ to XML you call the Load method of the XElement class to load the XML file. Once the XML file has been loaded, you write a LINQ query to iterate over the “Product” Descendants in the XML file. The “select” portion of the LINQ query creates a new Product object for each row in the XML file. You retrieve each attribute by passing each attribute name to the Attribute() method and retrieving the data from the “Value” property. The Value property will return a null if there is no data, or will return the string value of the attribute. The Convert class is used to convert the value retrieved into the appropriate data type required by the Product class. private void LoadProducts(){  XElement xElem = null;   try  {    xElem = XElement.Load(Product.XmlFile);     // The following will NOT work if you have missing attributes    var products =         from elem in xElem.Descendants("Product")        orderby elem.Attribute("ProductName").Value        select new Product        {          ProductId = Convert.ToInt32(            elem.Attribute("ProductId").Value),          ProductName = Convert.ToString(            elem.Attribute("ProductName").Value),          IntroductionDate = Convert.ToDateTime(            elem.Attribute("IntroductionDate").Value),          Price = Convert.ToDecimal(elem.Attribute("Price").Value)        };     lstData.DataContext = products;  }  catch (Exception ex)  {    MessageBox.Show(ex.Message);  }} This is where the problem comes in. If you have any missing attributes in any of the rows in the XML file, or if the data in the ProductId or IntroductionDate is not of the appropriate type, then this code will fail! The reason? There is no built-in check to ensure that the correct type of data is contained in the XML file. This is where extension methods can come in real handy. Using Extension Methods Instead of using the Convert class to perform type conversions as you just saw, create a set of extension methods attached to the XAttribute class. These extension methods will perform null-checking and ensure that a valid value is passed back instead of an exception being thrown if there is invalid data in your XML file. private void LoadProducts(){  var xElem = XElement.Load(Product.XmlFile);   var products =       from elem in xElem.Descendants("Product")      orderby elem.Attribute("ProductName").Value      select new Product      {        ProductId = elem.Attribute("ProductId").GetAsInteger(),        ProductName = elem.Attribute("ProductName").GetAsString(),        IntroductionDate =            elem.Attribute("IntroductionDate").GetAsDateTime(),        Price = elem.Attribute("Price").GetAsDecimal()      };   lstData.DataContext = products;} Writing Extension Methods To create an extension method you will create a class with any name you like. In the code listing below is a class named XmlExtensionMethods. This listing just shows a couple of the available methods such as GetAsString and GetAsInteger. These methods are just like any other method you would write except when you pass in the parameter you prefix the type with the keyword “this”. This lets the compiler know that it should add this method to the class specified in the parameter. public static class XmlExtensionMethods{  public static string GetAsString(this XAttribute attr)  {    string ret = string.Empty;     if (attr != null && !string.IsNullOrEmpty(attr.Value))    {      ret = attr.Value;    }     return ret;  }   public static int GetAsInteger(this XAttribute attr)  {    int ret = 0;    int value = 0;     if (attr != null && !string.IsNullOrEmpty(attr.Value))    {      if(int.TryParse(attr.Value, out value))        ret = value;    }     return ret;  }   ...  ...} Each of the methods in the XmlExtensionMethods class should inspect the XAttribute to ensure it is not null and that the value in the attribute is not null. If the value is null, then a default value will be returned such as an empty string or a 0 for a numeric value. Summary Extension methods are a great way to simplify your code and provide protection to ensure problems do not occur when reading data. You will probably want to create more extension methods to handle XElement objects as well for when you use element-based XML. Feel free to extend these extension methods to accept a parameter which would be the default value if a null value is detected, or any other parameters you wish. NOTE: You can download the complete sample code at my website. http://www.pdsa.com/downloads. Choose “Tips & Tricks”, then "Read XML Files using LINQ to XML and Extension Methods" from the drop-down. Good Luck with your Coding,Paul D. Sheriff  

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• BNF – how to read syntax?

  - by Piotr Rodak

  A few days ago I read post of Jen McCown (blog) about her idea of blogging about random articles from Books Online. I think this is a great idea, even if Jen says that it’s not exciting or sexy. I noticed that many of the questions that appear on forums and other media arise from pure fact that people asking questions didn’t bother to read and understand the manual – Books Online. Jen came up with a brilliant, concise acronym that describes very well the category of posts about Books Online – RTFM365. I take liberty of tagging this post with the same acronym. I often come across questions of type – ‘Hey, i am trying to create a table, but I am getting an error’. The error often says that the syntax is invalid. 1 CREATE TABLE dbo.Employees 2 (guid uniqueidentifier CONSTRAINT DEFAULT Guid_Default NEWSEQUENTIALID() ROWGUIDCOL, 3 Employee_Name varchar(60) 4 CONSTRAINT Guid_PK PRIMARY KEY (guid) ); 5 The answer is usually(1), ‘Ok, let me check it out.. Ah yes – you have to put name of the DEFAULT constraint before the type of constraint: 1 CREATE TABLE dbo.Employees 2 (guid uniqueidentifier CONSTRAINT Guid_Default DEFAULT NEWSEQUENTIALID() ROWGUIDCOL, 3 Employee_Name varchar(60) 4 CONSTRAINT Guid_PK PRIMARY KEY (guid) ); Why many people stumble on syntax errors? Is the syntax poorly documented? No, the issue is, that correct syntax of the CREATE TABLE statement is documented very well in Books Online and is.. intimidating. Many people can be taken aback by the rather complex block of code that describes all intricacies of the statement. However, I don’t know better way of defining syntax of the statement or command. The notation that is used to describe syntax in Books Online is a form of Backus-Naur notatiion, called BNF for short sometimes. This is a notation that was invented around 50 years ago, and some say that even earlier, around 400 BC – would you believe? Originally it was used to define syntax of, rather ancient now, ALGOL programming language (in 1950’s, not in ancient India). If you look closer at the definition of the BNF, it turns out that the principles of this syntax are pretty simple. Here are a few bullet points: italic_text is a placeholder for your identifier <italic_text_in_angle_brackets> is a definition which is described further. [everything in square brackets] is optional {everything in curly brackets} is obligatory everything | separated | by | operator is an alternative ::= “assigns” definition to an identifier Yes, it looks like these six simple points give you the key to understand even the most complicated syntax definitions in Books Online. Books Online contain an article about syntax conventions – have you ever read it? Let’s have a look at fragment of the CREATE TABLE statement: 1 CREATE TABLE 2 [ database_name . [ schema_name ] . | schema_name . ] table_name 3 ( { <column_definition> | <computed_column_definition> 4 | <column_set_definition> } 5 [ <table_constraint> ] [ ,...n ] ) 6 [ ON { partition_scheme_name ( partition_column_name ) | filegroup 7 | "default" } ] 8 [ { TEXTIMAGE_ON { filegroup | "default" } ] 9 [ FILESTREAM_ON { partition_scheme_name | filegroup 10 | "default" } ] 11 [ WITH ( <table_option> [ ,...n ] ) ] 12 [ ; ] Let’s look at line 2 of the above snippet: This line uses rules 3 and 5 from the list. So you know that you can create table which has specified one of the following. just name – table will be created in default user schema schema name and table name – table will be created in specified schema database name, schema name and table name – table will be created in specified database, in specified schema database name, .., table name – table will be created in specified database, in default schema of the user. Note that this single line of the notation describes each of the naming schemes in deterministic way. The ‘optionality’ of the schema_name element is nested within database_name.. section. You can use either database_name and optional schema name, or just schema name – this is specified by the pipe character ‘|’. The error that user gets with execution of the first script fragment in this post is as follows: Msg 156, Level 15, State 1, Line 2 Incorrect syntax near the keyword 'DEFAULT'. Ok, let’s have a look how to find out the correct syntax. Line number 3 of the BNF fragment above contains reference to <column_definition>. Since column_definition is in angle brackets, we know that this is a reference to notion described further in the code. And indeed, the very next fragment of BNF contains syntax of the column definition. 1 <column_definition> ::= 2 column_name <data_type> 3 [ FILESTREAM ] 4 [ COLLATE collation_name ] 5 [ NULL | NOT NULL ] 6 [ 7 [ CONSTRAINT constraint_name ] DEFAULT constant_expression ] 8 | [ IDENTITY [ ( seed ,increment ) ] [ NOT FOR REPLICATION ] 9 ] 10 [ ROWGUIDCOL ] [ <column_constraint> [ ...n ] ] 11 [ SPARSE ] Look at line 7 in the above fragment. It says, that the column can have a DEFAULT constraint which, if you want to name it, has to be prepended with [CONSTRAINT constraint_name] sequence. The name of the constraint is optional, but I strongly recommend you to make the effort of coming up with some meaningful name yourself. So the correct syntax of the CREATE TABLE statement from the beginning of the article is like this: 1 CREATE TABLE dbo.Employees 2 (guid uniqueidentifier CONSTRAINT Guid_Default DEFAULT NEWSEQUENTIALID() ROWGUIDCOL, 3 Employee_Name varchar(60) 4 CONSTRAINT Guid_PK PRIMARY KEY (guid) ); That is practically everything you should know about BNF. I encourage you to study the syntax definitions for various statements and commands in Books Online, you can find really interesting things hidden there. Technorati Tags: SQL Server,t-sql,BNF,syntax   (1) No, my answer usually is a question – ‘What error message? What does it say?’. You’d be surprised to know how many people think I can go through time and space and look at their screen at the moment they received the error.

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• unable to read/write CIFS mounts in Ubuntu 11.10

  - by Paul Collins

  upgraded my laptop from 11.04 too 11.10 and since then the CIFS mounts are not working before the upgrade it would allow mounts on host names, in 11.10 its only IP addresses (not much of an issue) however all the shares i mount are as Read only despite the FStab File declaring the options rw and auto, i have chowned the mount point to be nogroup.nouser and it still wont work, here is an extract from my FSTAB: //192.168.1.1/stories /home/paul/Documents/Stories cifs rw,user,exec,auto,username=,password= 0 0

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• "A Disk Read Error" while starting Windows after Ubuntu upgrade + Boot Repair

  - by bludger

  I just upgraded to 12.10. After installing the files and rebooting I had come across following problem: error file not found grub rescue _ This problem was easily solved by repairing the boot using Boot Repair tool. This answer helped me. But after this, Windows won't start. It's giving following error: A disk read error has occurred Press Ctrl+Alt+Del to restart How do I fix this?

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• Read Consistency & Deadlines: More control of your Datastore

  Last week we announced the 1.3.2 release of the App Engine SDK. We’re particularly excited about two new datastore features: eventually consistent reads, and datastore deadlines. Read Consistency...

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• .htaccess rewrite , parked domain on another site to read the proper domain name

  - by Stefano

  I have a parked domain ¨mysite.co.uk¨ on another domain name webspace in a folder and need to rewrite the mysite.co.uk domain name in the browser URL as it currently shows the Other domain name while browsing and i need it to read mysite.co.uk. When parking the domain the isp automatically added this which works although displays anotherdomain name. RewriteCond %{HTTP_HOST} ^mysite.co.uk$ [OR] RewriteCond %{HTTP_HOST} ^www.mysite.co.uk$ RewriteRule ^/?$ "http\://www.otherdomain.eu/myfolder" [R=301,L]

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• Make your TSQL easier to read during a presentation

  - by fatherjack

  SQL Server Management Studio 2012 has some neat settings that you can use to help your presentations at a SQL event better for the attendees if you are willing to spend a few minutes making some settings changes. Historically, I have been reluctant to make changes to my SSMS settings as it is such a tedious process and it's not 100% clear that what you think you are changing is actually what gets changed. With SSMS 2012 this has become a lot easier and a...(read more)

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• Read SQL Server Reporting Services Overview

  - by Editor

  Read an excellent, 14-page, general overview of Microsoft SQL Server 2008 Reporting Services entitled White Paper: Reporting Services in SQL Server 2008. Download the White Paper. (360 KB Microsoft Word file) White Paper: Reporting Services in SQL Server 2008 Microsoft SQL Server 2008 Reporting Services provides a complete server-based platform that is designed to support a wide variety [...]

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• Read and Write File to Local File System in Silverlight 4

  In Silverlight 4, we have an added feature that allows us to access Local File System. In this article we will see how we can read and write a file to local file system.

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• How Do Search Engine Bots Read Your Website?

  Do you ever think of how the search engines interpret and read your website? Is it the same like human beings? It's completely different.

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• Become Popular With Your First Blog Post - Read Before You Start

  Before blogging, keep the following in mind - Why should people read your blog? Why are you at all going public with what's-in-your-mind? Considering these things will help you get the best traffic at your webpage.

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• Make your TSQL easier to read during a presentation

  - by fatherjack

  SQL Server Management Studio 2012 has some neat settings that you can use to help your presentations at a SQL event better for the attendees if you are willing to spend a few minutes making some settings changes. Historically, I have been reluctant to make changes to my SSMS settings as it is such a tedious process and it's not 100% clear that what you think you are changing is actually what gets changed. With SSMS 2012 this has become a lot easier and a...(read more)

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• MySQL Master-Master w/ multiple read slave cost effective setup in AWS

  - by Ross

  I've been evaluating Amazon Web Services RDS for MySQL and costing out potential scenarios involving a simple multi-AZ deployment read/write setup vs. a multi-AZ deployment mysql master (hot-standby) with additional read-only slaves. the issue I'm trying to cost-optimize includes their reserved instance vs on-demand instances. Situation 1: purchase reserved multi-az setup for Extra-large-hi-mem(17GB RAM) instance for $5200/yr and have my application query the master all the time. the problem is, if I don't need all the resources of the (17GB RAM) all the time and therefore, especially not a hot-standby, what alternatives for savings can a better topology create, like potentially situation 2 below: Situation 2: purchase reserved multi-az setup using smaller master instances than above for the master-master hot-standby to receive the writes only. Then create and load balance several read-only slaves off the master and add/remove and/or scale up/down the read slaves based on demand. This might only cost $1000 + the on-demand usage of the read slaves. My thinking is, if I have a variable read-intensive application load, with low write load, the single level topology in situation 1 means I'm paying for a lot of resources at the write level of topology when I don't need them there. My hope is that situation 2 can yield cost savings from smaller reserved instances on the master-master resource level allowing me to scale up and down and/or out on the read-level according to demand as needed. Does anyone see a downside to doing this or know of some reason this isn't possible with RDS? Any other thoughts or advice always welcome of course. Thanks in advance, R

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• OAM OVD integration - Error Encounterd while performance test "LDAP response read timed out, timeout used:2000ms"

  - by siddhartha_sinha

  While working on OAM OVD integration for one of my client, I have been involved in the performance test of the products wherein I encountered OAM authentication failures while talking to OVD during heavy load. OAM logs revealed the following: oracle.security.am.common.policy.common.response.ResponseException: oracle.security.am.engines.common.identity.provider.exceptions.IdentityProviderException: OAMSSA-20012: Exception in getting user attributes for user : dummy_user1, idstore MyIdentityStore with exception javax.naming.NamingException: LDAP response read timed out, timeout used:2000ms.; remaining name 'ou=people,dc=oracle,dc=com' at oracle.security.am.common.policy.common.response.IdentityValueProvider.getUserAttribute(IdentityValueProvider.java:271) ... During the authentication and authorization process, OAM complains that the LDAP repository is taking too long to return user attributes.The default value is 2 seconds as can be seen from the exception, "2000ms". While troubleshooting the issue, it was found that we can increase the ldap read timeout in oam-config.xml.  For reference, the attribute to add in the oam-config.xml file is: <Setting Name="LdapReadTimeout" Type="xsd:string">2000</Setting> However it is not recommended to increase the time out unless it is absolutely necessary and ensure that back-end directory servers are working fine. Rather I took the path of tuning OVD in the following manner: 1) Navigate to ORACLE_INSTANCE/config/OPMN/opmn folder and edit opmn.xml. Search for <data id="java-options" ………> and edit the contents of the file with the highlighted items: <category id="start-options"><data id="java-bin" value="$ORACLE_HOME/jdk/bin/java"/><data id="java-options" value="-server -Xms1024m -Xmx1024m -Dvde.soTimeoutBackend=0 -Didm.oracle.home=$ORACLE_HOME -Dcommon.components.home=$ORACLE_HOME/../oracle_common -XX:+PrintGCDetails -XX:+PrintGCDateStamps -Xloggc:/opt/bea/Middleware/asinst_1/diagnostics/logs/OVD/ovd1/ovdGClog.log -XX:+UseConcMarkSweepGC -Doracle.security.jps.config=$ORACLE_INSTANCE/config/JPS/jps-config-jse.xml"/><data id="java-classpath" value="$ORACLE_HOME/ovd/jlib/vde.jar$:$ORACLE_HOME/jdbc/lib/ojdbc6.jar"/></category></module-data><stop timeout="120"/><ping interval="60"/></process-type> When the system is busy, a ping from the Oracle Process Manager and Notification Server (OPMN) to Oracle Virtual Directory may fail. As a result, OPMN will restart Oracle Virtual Directory after 20 seconds (the default ping interval). To avoid this, consider increasing the ping interval to 60 seconds or more. 2) Navigate to ORACLE_INSTANCE/config/OVD/ovd1 folder.Open listeners.os_xml file and perform the following changes: · Search for <ldap id=”Ldap Endpoint”…….> and point the cursor to that line. · Change threads count to 200. · Change anonymous bind to Deny. · Change workQueueCapacity to 8096. Add a new parameter <useNIO> and set its value to false viz: <useNIO>false</useNio> Snippet: <ldap version="8" id="LDAP Endpoint"> ....... .......  <socketOptions><backlog>128</backlog>         <reuseAddress>false</reuseAddress>         <keepAlive>false</keepAlive>         <tcpNoDelay>true</tcpNoDelay>         <readTimeout>0</readTimeout>      </socketOptions> <useNIO>false</useNIO></ldap> Restart OVD server. For more information on OVD tuneup refer to http://docs.oracle.com/cd/E25054_01/core.1111/e10108/ovd.htm. Please Note: There were few patches released from OAM side for performance tune-up as well. Will provide the updates shortly !!!

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• Write, Read and Update Oracle CLOBs with PL/SQL

  - by robertphyatt

  Fun with CLOBS! If you are using Oracle, if you have to deal with text that is over 4000 bytes, you will probably find yourself dealing with CLOBs, which can go up to 4GB. They are pretty tricky, and it took me a long time to figure out these lessons learned. I hope they will help some down-trodden developer out there somehow. Here is my original code, which worked great on my Oracle Express Edition: (for all examples, the first one writes a new CLOB, the next one Updates an existing CLOB and the final one reads a CLOB back) CREATE OR REPLACE PROCEDURE PRC_WR_CLOB (        p_document      IN VARCHAR2,        p_id            OUT NUMBER) IS      lob_loc CLOB; BEGIN    INSERT INTO TBL_CLOBHOLDERDDOC (CLOBHOLDERDDOC)        VALUES (empty_CLOB())        RETURNING CLOBHOLDERDDOC, CLOBHOLDERDDOCID INTO lob_loc, p_id;    DBMS_LOB.WRITE(lob_loc, LENGTH(UTL_RAW.CAST_TO_RAW(p_document)), 1, UTL_RAW.CAST_TO_RAW(p_document)); END; / CREATE OR REPLACE PROCEDURE PRC_UD_CLOB (        p_document      IN VARCHAR2,        p_id            IN NUMBER) IS      lob_loc CLOB; BEGIN        SELECT CLOBHOLDERDDOC INTO lob_loc FROM TBL_CLOBHOLDERDDOC        WHERE CLOBHOLDERDDOCID = p_id FOR UPDATE;    DBMS_LOB.WRITE(lob_loc, LENGTH(UTL_RAW.CAST_TO_RAW(p_document)), 1, UTL_RAW.CAST_TO_RAW(p_document)); END; / CREATE OR REPLACE PROCEDURE PRC_RD_CLOB (    p_id IN NUMBER,    p_clob OUT VARCHAR2) IS    lob_loc  CLOB; BEGIN    SELECT CLOBHOLDERDDOC INTO lob_loc    FROM   TBL_CLOBHOLDERDDOC    WHERE  CLOBHOLDERDDOCID = p_id;    p_clob := UTL_RAW.CAST_TO_VARCHAR2(DBMS_LOB.SUBSTR(lob_loc, DBMS_LOB.GETLENGTH(lob_loc), 1)); END; / As you can see, I had originally been casting everything back and forth between RAW formats using the UTL_RAW.CAST_TO_VARCHAR2() and UTL_RAW.CAST_TO_RAW() functions all over the place, but it had the nasty side effect of working great on my Oracle express edition on my developer box, but having all the CLOBs above a certain size display garbage when read back on the Oracle test database server . So...I kept working at it and came up with the following, which ALSO worked on my Oracle Express Edition on my developer box:   CREATE OR REPLACE PROCEDURE PRC_WR_CLOB (     p_document      IN VARCHAR2,     p_id        OUT NUMBER) IS       lob_loc CLOB; BEGIN     INSERT INTO TBL_CLOBHOLDERDOC (CLOBHOLDERDOC)         VALUES (empty_CLOB())         RETURNING CLOBHOLDERDOC, CLOBHOLDERDOCID INTO lob_loc, p_id;     DBMS_LOB.WRITE(lob_loc, LENGTH(p_document), 1, p_document);   END; / CREATE OR REPLACE PROCEDURE PRC_UD_CLOB (     p_document      IN VARCHAR2,     p_id        IN NUMBER) IS       lob_loc CLOB; BEGIN     SELECT CLOBHOLDERDOC INTO lob_loc FROM TBL_CLOBHOLDERDOC     WHERE CLOBHOLDERDOCID = p_id FOR UPDATE;     DBMS_LOB.WRITE(lob_loc, LENGTH(p_document), 1, p_document); END; / CREATE OR REPLACE PROCEDURE PRC_RD_CLOB (     p_id IN NUMBER,     p_clob OUT VARCHAR2) IS     lob_loc  CLOB; BEGIN     SELECT CLOBHOLDERDOC INTO lob_loc     FROM   TBL_CLOBHOLDERDOC     WHERE  CLOBHOLDERDOCID = p_id;     p_clob := DBMS_LOB.SUBSTR(lob_loc, DBMS_LOB.GETLENGTH(lob_loc), 1); END; / Unfortunately, by changing my code to what you see above, even though it kept working on my Oracle express edition, everything over a certain size just started truncating after about 7950 characters on the test server! Here is what I came up with in the end, which is actually the simplest solution and this time worked on both my express edition and on the database server (note that only the read function was changed to fix the truncation issue, and that I had Oracle worry about converting the CLOB into a VARCHAR2 internally): CREATE OR REPLACE PROCEDURE PRC_WR_CLOB (        p_document      IN VARCHAR2,        p_id            OUT NUMBER) IS      lob_loc CLOB; BEGIN    INSERT INTO TBL_CLOBHOLDERDDOC (CLOBHOLDERDDOC)        VALUES (empty_CLOB())        RETURNING CLOBHOLDERDDOC, CLOBHOLDERDDOCID INTO lob_loc, p_id;    DBMS_LOB.WRITE(lob_loc, LENGTH(p_document), 1, p_document); END; / CREATE OR REPLACE PROCEDURE PRC_UD_CLOB (        p_document      IN VARCHAR2,        p_id            IN NUMBER) IS      lob_loc CLOB; BEGIN        SELECT CLOBHOLDERDDOC INTO lob_loc FROM TBL_CLOBHOLDERDDOC        WHERE CLOBHOLDERDDOCID = p_id FOR UPDATE;    DBMS_LOB.WRITE(lob_loc, LENGTH(p_document), 1, p_document); END; / CREATE OR REPLACE PROCEDURE PRC_RD_CLOB (    p_id IN NUMBER,    p_clob OUT VARCHAR2) IS BEGIN    SELECT CLOBHOLDERDDOC INTO p_clob    FROM   TBL_CLOBHOLDERDDOC    WHERE  CLOBHOLDERDDOCID = p_id; END; /   I hope that is useful to someone!

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• Make your TSQL easier to read during a presentation

  - by Jonathan Allen

  SQL Server Management Studio 2012 has some neat settings that you can use to help your presentations at a SQL event better for the attendees if you are willing to spend a few minutes making some settings changes. Historically, I have been reluctant to make changes to my SSMS settings as it is such a tedious process and it’s not 100% clear that what you think you are changing is actually what gets changed. With SSMS 2012 this has become a lot easier and a lot less risky. In any session that involves TSQL there is a trade off between the speaker having all the code on screen and the attendees being able to read any of what is on screen. You (the speaker) might be able to read this when you are working on the code but plenty of your audience wont be able to make head or tail of it. SSMS 2012 has a zoom facility that can help: but don’t go nuts … Having the font too big means you will be scrolling a lot and the code will again be rendered unreadable. There is more though but you need to take a deep breath and open the Tools menu and delve into the SSMS options. In previous versions of SSMS this is a deep, dark and scary place where changing values can be obscure and sometimes catastrophic to the UI when you get back to the code editor. First things first, we set out as a good DBA and save our current (and presumably acceptable) SSMS configuration. From the import and Export Settings you can set up a file to hold all of the settings that you currently have. The wizard will open and ask you to pick an option. This time around choose to export settings. hit next and next again and then name your settings profile in the final step of the wizard and then click Finish. Once this is done then you can change whatever you like and always get back to this configuration in a couple of clicks. So what can you change to make for a good experience? Well there are plenty of things that can be altered but don’t go too mad and change too many things without taking a look at the results for every item on the list above you can change font, size, weight, colour, background colour etc. etc. but consider what you are trying to achieve and take it slowly. I have seen presenters with their settings set to have a yellow highlight and black font rather than the default pale blue background and slightly darker font so to achieve that select Text Editor and then select “Selected Text” in the Display Items listbox. As you change things the Sample area give you an idea of what effect you are going to have. Black and yellow is the colour combination with the highest contrast – that’s why bees and wasps# are that colour. What next? how about increasing the default font for your demo scripts? This means that any script you open and any new ones that you start will take on this font. No more zooming (or forgetting to) in the middle of sessions. now don’t forget to save this profile – follow the same steps as above but give the profile a different name, something like PresentationBigFontHighContrast might be appropriate. Once you are done making changes, export the settings once more and then go into the Import Export wizard and import settings from the first profile you created. Everything will be back to normal. Now making changes to suit your environment can be done very easily and with confidence. * – and warning tape and safety signs and so forth – Health and Safety officers simply copy nature!

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• windows 2003 server read only access

  - by Bruce227

  Hi, I'm having a read only access problem. I have admin rights and can set the security for a folder to give me full access but when I switch the check box for read only off then exit out and open the properties back up it is checked. It is a grayed out check box if that helps. I just don't know how I have read/write access but can't switch off read only for a particular folder. Thanks

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• The configuration section 'system.web.extensions' cannot be read because it is missing a section declaration

  - by Jeff Widmer

  After upgrading an ASP.NET application from .NET Framework 3.5 to .NET Framework 4.0 I ran into the following error message dialog when trying to view any of the modules in IIS on the server. What happened is during the upgrade, the web.config file was automatically converted for .NET Framework 4.0.  This left behind an empty system.web.extensions section: It was an easy fix to resolve, just remove the unused system.web.extensions section.   ERROR DIALOG TEXT: --------------------------- ASP --------------------------- There was an error while performing this operation. Details: Filename: \\?\web.config Line number: 171 Error: The configuration section 'system.web.extensions' cannot be read because it is missing a section declaration --------------------------- OK   ---------------------------

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• I cannot read second internal HD

  - by Nathan

  I reformatted my Win "C" drive and loaded Ubuntu 11.04. The second internal HD of course is not read. It is shown in 'disk utility'. I try to mount it in disk utility but I get an error message error mounting: mount exited with exit code 1: helper failed with: mount: according to mtab, /dev/sda1 is already mounted on / One problem I see is the error relates to sda1, but I am trying to mount sdb. Unfortunately, I am windows literate and ignorant of the coding for linux. Can someone help me with the code to mount my second drive (sdb) Nathan

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