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• Need help choosing database server

  - by The Pretender

  Good day everyone. Recently I was given a task to develop an application to automate some aspects of stocks trading. While working on initial architecture, the database dilemma emerged. What I need is a fast database engine which can process huge amounts of data coming in very fast. I'm fairly experienced in general programming, but I never faced a task of developing a high-load database architecture. I developed a simple MSSQL database schema with several many-to-many relationships during one of my projects, but that's it. What I'm looking for is some advice on choosing the most suitable database engine and some pointers to various manuals or books which describe high-load database development. Specifics of the project are as follows: OS: Windows NT family (Server 2008 / 7) Primary platform: .NET with C# Database structure: one table to hold primary items and two or three tables with foreign keys to the first table to hold additional information. Database SELECT requirements: Need super-fast selection by foreign keys and by combination of foreign key and one of the columns (presumably DATETIME) Database INSERT requirements: The faster the better :) If there'll be significant performance gain, some parts can be written in C++ with managed interfaces to the rest of the system. So once again: given all that stuff I just typed, please give me some advice on what the best database for my project is. Links or references to some manuals and books on the subject are also greatly appreciated. EDIT: I'll need to insert 3-5 rows in 2 tables approximately once in 30-50 milliseconds and I'll need to do SELECT with 0-2 WHERE clauses queries with similar rate.

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• SQL Server: Is it possible to prevent SQL Agent from failing a step on error?

  - by Kenneth

  I have a stored procedure that runs custom backups for around 60 SQL servers (mixes 2000 through 2008R2). Occasionally, due to issues outside of my control (backup device inaccessible, network error, etc.) an individual backup on one or two databases will fail. This causes this entire step to fail, which means any subsequent backup commands are not executed and half of the databases on a given server may not be backed up. On the 2005+ boxes I am using TRY/CATCH blocks to manage these problems and continue backing up the remaining databases. On a 2000 server however, for example, I have no way to prevent this error from failing the entire step: Msg 3201, Level 16, State 1, Line 1 Cannot open backup device 'db-diff(\PATH\DB-DIFF-03-16-2010.DIF)'. Operating system error 5(Access is denied.). Msg 3013, Level 16, State 1, Line 1 BACKUP DATABASE is terminating abnormally. I am simply asking if anything like TRY/CATCH is possible in SQL 2000? I realize there are no built in methods for this, so I guess I am looking for some creativity. Even when wrapping each backup (or any failing statement) via sp_executesql the job fails instantly. Example: DECLARE @x INT, @iReturn INT PRINT 'Executing statement that will fail with 208.' EXEC @iReturn = Sp_executesql N'SELECT * from TABLETHATDOESNTEXIST;' PRINT Cast(@iReturn AS NVARCHAR) --In SSMS this return code prints. Executed as a job it fails and aborts before this statement.

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• Best architecture for a social media app

  - by Sky

  Hey guys, Im working on promising project that develops a new social media app for web and mobile. We are at begin defining functionalities. Nevertheless, I'm thinking ahead on architecture. So I'm asking: 1 - Whats the best plataform to develop the core of this aplication that will have a Rest API interface. 2 - Whats the best database that will scale and grow with my application. As far as I researched, these were the answers I found most interesting: For database: Cassandra NoSQL DB, amazing scalabilty, amazing write performance, good read performance (will be improved on 0.6). I think i will choose that one. Zookeer for transactions on Cassandra. I think that 2 technologies rly good for that propose. What do you think guys? On the front end that will serve the REST API, i dont have a final candidate. For this one i have questions based on Perfomance X Scalabilty X Fast Development/Maintenance. Java or .Net As far as I researched, brings the best balance of this requisits. Python, pearl and Rail, has the best (Fast Development/Maintenance), but sux on all other. C or C++ I dont even consider, because its (Fast Development/Maintenance) sux... So what do you guy think about it?

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• Applets failing to load

  - by Roy Tang

  While testing our setup for user acceptance testing, we got some reports that java applets in our web application would occasionally fail to load. The envt where it was reported was WinXP/IE6, and there were no errors found in the java console. Obviously we'd like to avoid it. What sort of things should we be checking for here? On our local servers, everything seems fine. There's some turnaround time when sending questions to the on-site guy, so I'd look to cover as many possible causes as possible. Some more info: We have multiple applets, in the instance that they fail loading, all of them fail loading. The applet jar files vary in size from 2MB to 8MB. I'm told it seems more likely to happen if the applet isn't cached yet, i.e. if they've been able to load the applets once on a given machine, further runs on that machine go smoothly. I'm wondering if there's some sort of network transfer error when downloading the applets, but I don't know how to verify that. Any advise is welcome!

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• Slow MySQL Query not using filesort

  - by Canadaka

  I have a query on my homepage that is getting slower and slower as my database table grows larger. tablename = tweets_cache rows = 572,327 this is the query I'm currently using that is slow, over 5 seconds. SELECT * FROM tweets_cache t WHERE t.province='' AND t.mp='0' ORDER BY t.published DESC LIMIT 50; If I take out either the WHERE or the ORDER BY, then the query is super fast 0.016 seconds. I have the following indexes on the tweets_cache table. PRIMARY published mp category province author So i'm not sure why its not using the indexes since mp, provice and published all have indexes? Doing a profile of the query shows that its not using an index to sort the query and is using filesort which is really slow. possible_keys = mp,province Extra = Using where; Using filesort I tried adding a new multie-colum index with "profiles & mp". The explain shows that this new index listed under "possible_keys" and "key", but the query time is unchanged, still over 5 seconds. Here is a screenshot of the profiler info on the query. http://i355.photobucket.com/albums/r469/canadaka_bucket/slow_query_profile.png Something weird, I made a dump of my database to test on my local desktop so i don't screw up the live site. The same query on my local runs super fast, milliseconds. So I copied all the same mysql startup variables from the server to my local to make sure there wasn't some setting that might be causing this. But even after that the local query runs super fast, but the one on the live server is over 5 seconds. My database server is only using around 800MB of the 4GB it has available. here are the related my.ini settings i'm using default-storage-engine = MYISAM max_connections = 800 skip-locking key_buffer = 512M max_allowed_packet = 1M table_cache = 512 sort_buffer_size = 4M read_buffer_size = 4M read_rnd_buffer_size = 16M myisam_sort_buffer_size = 64M thread_cache_size = 8 query_cache_size = 128M # Try number of CPU's*2 for thread_concurrency thread_concurrency = 8 # Disable Federated by default skip-federated key_buffer = 512M sort_buffer_size = 256M read_buffer = 2M write_buffer = 2M key_buffer = 512M sort_buffer_size = 256M read_buffer = 2M write_buffer = 2M

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• WCF service returns error 500 on /js request

  - by Cine

  I have a wcf service that randomly begins to fail when requesting the autogenerated javascript that wcf supports making. But I have no luck tracking down why. The js thing is part of the wcf featureset, so I dont know how it can suddenly begin to fail and be unable to work until IIS is recycled. The http log gives me: 2010-06-10 09:11:49 W3SVC2095255988 myip GET /path/myservice.svc/js _=1276161113900 80 - ip browser 500 0 0 So its an error 500, and that is about the only thing I can figure out. The event log contains no information. Requests to /path/myservice.svc works just fine. After recycling IIS it works again, and some days later it begins to fail until I recycle IIS. <service name="path.myservice" behaviorConfiguration="b"> <endpoint address="" behaviorConfiguration="eb" binding="webHttpBinding" contract="path.Imyservice" /> </service> ... <endpointBehaviors> <behavior name="eb"> <enableWebScript /> </behavior> </endpointBehaviors> <serviceBehaviors> <behavior name="b"> <dataContractSerializer maxItemsInObjectGraph="2147483647" /> <serviceMetadata httpGetEnabled="true" /> <serviceDebug includeExceptionDetailInFaults="true" /> </behavior> </serviceBehaviors> I dont see any problems in the web.config settings either. Any clues how I can track down what the problem is?

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• Weirdness with cabal, HTF, and HUnit assertions

  - by rampion

  So I'm trying to use HTF to run some HUnit-style assertions % cat tests/TestDemo.hs {-# OPTIONS_GHC -Wall -F -pgmF htfpp #-} module Main where import Test.Framework import Test.HUnit.Base ((@?=)) import System.Environment (getArgs) -- just run some tests main :: IO () main = getArgs >>= flip runTestWithArgs Main.allHTFTests -- all these tests should fail test_fail_int1 :: Assertion test_fail_int1 = (0::Int) @?= (1::Int) test_fail_bool1 :: Assertion test_fail_bool1 = True @?= False test_fail_string1 :: Assertion test_fail_string1 = "0" @?= "1" test_fail_int2 :: Assertion test_fail_int2 = [0::Int] @?= [1::Int] test_fail_string2 :: Assertion test_fail_string2 = "true" @?= "false" test_fail_bool2 :: Assertion test_fail_bool2 = [True] @?= [False] And when I use ghc --make, it seems to work correctly. % ghc --make tests/TestDemo.hs [1 of 1] Compiling Main ( tests/TestDemo.hs, tests/TestDemo.o ) Linking tests/TestDemo ... % tests/TestDemoA ... * Tests: 6 * Passed: 0 * Failures: 6 * Errors: 0 Failures: * Main:fail_int1 (tests/TestDemo.hs:9) * Main:fail_bool1 (tests/TestDemo.hs:12) * Main:fail_string1 (tests/TestDemo.hs:15) * Main:fail_int2 (tests/TestDemo.hs:19) * Main:fail_string2 (tests/TestDemo.hs:22) * Main:fail_bool2 (tests/TestDemo.hs:25) But when I use cabal to build it, not all the tests that should fail, fail. % cat Demo.cabal ... executable test-demo build-depends: base >= 4, HUnit, HTF main-is: TestDemo.hs hs-source-dirs: tests % cabal configure Resolving dependencies... Configuring Demo-0.0.0... % cabal build Preprocessing executables for Demo-0.0.0... Building Demo-0.0.0... [1 of 1] Compiling Main ( tests/TestDemo.hs, dist/build/test-demo/test-demo-tmp/Main.o ) Linking dist/build/test-demo/test-demo ... % dist/build/test-demo/test-demo ... * Tests: 6 * Passed: 3 * Failures: 3 * Errors: 0 Failures: * Main:fail_int2 (tests/TestDemo.hs:23) * Main:fail_string2 (tests/TestDemo.hs:26) * Main:fail_bool2 (tests/TestDemo.hs:29) What's going wrong and how can I fix it?

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• Yet another "What is this code doing"-type of Perl code

  - by Mike

  I have inherited some code from a guy whose favorite past time was to shorten every line to its absolute minimum (and sometimes only to make it look cool). His code is hard to understand but I managed to understand (and rewrite) most of it. Now I have stumbled on a piece of code which, no matter how hard I try, I cannot understand. my @heads = grep {s/\.txt$//} OSA::Fast::IO::Ls->ls($SysKey,'fo','osr/tiparlo',qr{^\d+\.txt$}) || (); my @selected_heads = (); for my $i (0..1) { $selected_heads[$i] = int rand scalar @heads; for my $j (0..@heads-1) { last if (!grep $j eq $_, @selected_heads[0..$i-1]); $selected_heads[$i] = ($selected_heads[$i] + 1) % @heads; #WTF? } my $head_nr = sprintf "%04d", $i; OSA::Fast::IO::Cp->cp($SysKey,'',"osr/tiparlo/$heads[$selected_heads[$i]].txt","$recdir/heads/$head_nr.txt"); OSA::Fast::IO::Cp->cp($SysKey,'',"osr/tiparlo/$heads[$selected_heads[$i]].cache","$recdir/heads/$head_nr.cache"); } From what I can understand, this is supposed to be some kind of randomizer, but I never saw a more complex way to achieve randomness. Or are my assumptions wrong? At least, that's what this code is supposed to do. Select 2 random files and copy them. === NOTES === The OSA Framework is a Framework of our own. They are named after their UNIX counterparts and do some basic testing so that the application does not need to bother with that.

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• Ruby array, javascript and json issue

  - by JohnMerlino

  Hey all, I am unable to get a highcharts plugin to render a chart in a rails application: http://github.com/loudpixel/highcharts-rails I believe it has something to do with the sql queries to the database placed in a ruby array, which the javascript is unable to intepret. This is what I have: def panels pass = Student.find_by_sql('SELECT COUNT(*) FROM students WHERE student_state = 1') fail = Student.find_by_sql('SELECT COUNT(*) FROM students WHERE student_state = 2') student_data = [ {:name => 'Pass', :y => pass}, {:name => 'Fail', :y => fail} ] pie_label_formatter = ' function() { if (this.y > 15) return this.point.name; }' pie_tooltip_formatter = ' function() { return "<strong>" + this.point.name + "</strong>: " + this.y + " %"; }' @pie_chart = Highchart.pie({ :chart => { :renderTo => "pie-chart-container", :margin => [50, 30, 0, 30] }, :plotOptions => { :pie => { :dataLabels => { :formatter => pie_label_formatter, :style => { :textShadow => '#000000 1px 1px 2px' } } } }, :series => [ { :type => 'pie', :data => student_data } ], :subtitle => { :text => 'April 2010' }, :title => { :text => 'Student Status Chart' }, :tooltip => { :formatter => pie_tooltip_formatter }, }) Note if I put this: :data = student_data.to_json It actually returns a json string of my query as text in the browser. Also, if I hard code values (e.g. :y = 1), it will render the chart properly. However, any database query will not render the chart properly. So I'm not sure exactly what the issue is. Any suggestions? Thanks.

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• Interrupting Prototype handler, alert() vs event.stop()

  - by lxs

  Here's the test page I'm using. This version works fine, forwarding to #success: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html><head> <script type="text/javascript" src="prototype.js"></script> </head><body> <form id='form' method='POST' action='#fail'> <button id='button'>Oh my giddy aunt!</button> <script type="text/javascript"> var fn = function() { $('form').action = "#success"; $('form').submit(); } $('button').observe('mousedown', fn); </script> </form> </body></html> If I empty the handler: var fn = function() { } The form is submitted, but of course we are sent to #fail this time. With an alert in the handler: var fn = function() { alert("omg!"); } The form is not submitted. This is awfully curious. With event.stop(), which is supposed to prevent the browser taking the default action: var fn = function(event) { event.stop(); } We are sent to #fail. So alert() is more effective at preventing a submission than event.stop(). What gives? I'm using Firefox 3.6.3 and Prototype 1.6.0.3. This behaviour also appears in Prototype 1.6.1.

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• Adding one subquery makes query a little slower, adding another makes it way slower

  - by Jason Swett

  This is fast: select ba.name, penamt.value penamt, #address_line4.value address_line4 from account a join customer c on a.customer_id = c.id join branch br on a.branch_id = br.id join bank ba on br.bank_id = ba.id join account_address aa on aa.account_id = a.id join address ad on aa.address_id = ad.id join state s on ad.state_id = s.id join import i on a.import_id = i.id join import_bundle ib on i.import_bundle_id = ib.id join (select * from unused where heading_label = 'PENAMT') penamt ON penamt.account_id = a.id #join (select * from unused where heading_label = 'Address Line 4') address_line4 ON address_line4.account_id = a.id where i.active=1 And this is fast: select ba.name, #penamt.value penamt, address_line4.value address_line4 from account a join customer c on a.customer_id = c.id join branch br on a.branch_id = br.id join bank ba on br.bank_id = ba.id join account_address aa on aa.account_id = a.id join address ad on aa.address_id = ad.id join state s on ad.state_id = s.id join import i on a.import_id = i.id join import_bundle ib on i.import_bundle_id = ib.id #join (select * from unused where heading_label = 'PENAMT') penamt ON penamt.account_id = a.id join (select * from unused where heading_label = 'Address Line 4') address_line4 ON address_line4.account_id = a.id where i.active=1 But this is slow: select ba.name, penamt.value penamt, address_line4.value address_line4 from account a join customer c on a.customer_id = c.id join branch br on a.branch_id = br.id join bank ba on br.bank_id = ba.id join account_address aa on aa.account_id = a.id join address ad on aa.address_id = ad.id join state s on ad.state_id = s.id join import i on a.import_id = i.id join import_bundle ib on i.import_bundle_id = ib.id join (select * from unused where heading_label = 'PENAMT') penamt ON penamt.account_id = a.id join (select * from unused where heading_label = 'Address Line 4') address_line4 ON address_line4.account_id = a.id where i.active=1 Why is it fast when I include just one of the two subqueries but slow when I include both? I would think it should be twice as slow when I include both, but it takes a really long time. On on MySQL.

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• Project management and bundling dependencies

  - by Joshua

  I've been looking for ways to learn about the right way to manage a software project, and I've stumbled upon the following blog post. I've learned some of the things mentioned the hard way, others make sense, and yet others are still unclear to me. To sum up, the author lists a bunch of features of a project and how much those features contribute to a project's 'suckiness' for a lack of a better term. You can find the full article here: http://spot.livejournal.com/308370.html In particular, I don't understand the author's stance on bundling dependencies with your project. These are: == Bundling == Your source only comes with other code projects that it depends on [ +20 points of FAIL ] Why is this a problem, (especially given the last point)? If your source code cannot be built without first building the bundled code bits [ +10 points of FAIL ] Doesn't this necessarily have to be the case for software built against 3rd party libs? Your code needs that other code to be compiled into its library before the linker can work? If you have modified those other bundled code bits [ +40 points of FAIL ] If this is necessary for your project, then it naturally follows that you've bundled said code with yours. If you want to customize a build of some lib,say WxWidgets, you'll have to edit that projects build scripts to bulid the library that you want. Subsequently, you'll have to publish those changes to people who wish to build your code, so why not use a high level make script with the params already written in, and distribute that? Furthermore, (especially in a windows env) if your code base is dependent on a particular version of a lib (that you also need to custom compile for your project) wouldn't it be easier to give the user the code yourself (because in this case, it is unlikely that the user will already have the correct version installed)? So how would you respond to these comments, and what points may I be failing to take into consideration? Would you agree or disagree with the author's take (or mine), and why?

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• Problem: writing parameter values to data driven MSTEST output

  - by Shubh

  Hi, I am trying to extract some information about the parameter variants used in an MSTEST data driven test case from trx file. Currently, For data driven tests, I get the output of same testcase with different inputs as a sequence of tags , but there is no info about the value of the variants. Example: Suppose we have a [data driven]TestMethod1() and the data rows contain variations a and b. There are two variations a=1,b=2 for which the test passes and a=3,b=4 for which the test fails. If we can output the info that it was a=1,b=2 which passed and a=3 b=4 which failed in the trx file; the output will be meaningful. Better information about test case runs from the output file alone(without any dependencies). Investigating the test failure without rerunning the whole set If the data rows change in data source(now a=1,b=2 pass and a=5,b=6 fail) , easy to decipher that the errors are different; although the fail sequence is still the same(row 0 pass row 1 fail but now row1 is different) Has any of you gone through a similar problem? What did you follow? I tried to put the parameter value information in the Description attribute of TestMethod, it didnt work. Any other methods you think can work too? thanks, Shubhankar

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• Maven Cobertura: unit test failed but build success

  - by Pavel Drobushevich

  Hi all, I've configured cobertura code coverage in my pom: <plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>cobertura-maven-plugin</artifactId> <version>2.4</version> <configuration> <instrumentation> <excludes> <exclude>**/*Exception.class</exclude> </excludes> </instrumentation> <formats> <format>xml</format> <format>html</format> </formats> </configuration> </plugin> And start test by following command: mvn clean cobertura:cobertura But if one of unit test fail Cobertura only log this information and doesn't mark build fail. Tests run: 287, Failures: 1, Errors: 1, Skipped: 0 Flushing results... Flushing results done Cobertura: Loaded information on 139 classes. Cobertura: Saved information on 139 classes. [ERROR] There are test failures. ................................. [INFO] BUILD SUCCESS How to configure Cobertura marks build failed in one of unit test fail? Thanks in advance.

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• How to Return Variable for all tests to use Unittest

  - by chrissygormley

  Hello, I have a Python script and I am trying to set a variable so that if the first test fail's the rest of then will be set to fail. The script I have so far is: class Tests(): def function: result function.......... def errorHandle(self): return self.error def sudsPass(self): try: result = self.client.service.GetStreamUri(self.stream, self.token) except suds.WebFault, e: assert False except Exception, e: pass finally: if 'result' in locals(): self.error = True self.errorHandle() assert True else: self.error = False self.errorHandle() assert False def sudsFail(self): try: result = self.client.service.GetStreamUri(self.stream, self.token) except suds.WebFault, e: assert False except Exception, e: pass finally: if 'result' in locals() or self.error == False: assert False else: assert True class GetStreamUri(TestGetStreamUri): def runTest(self): self.sudsPass() class GetStreamUriProtocolFail(TestGetStreamUri): def runTest(self): self.stream.Transport.Protocol = "NoValue" self.errorHandle() self.sudsFail() if __name__ == '__main__': unittest.main() I am trying to get self.error to be set to False if the first test fail. I understand that it is being set in another test but I was hoping someone could help me find a solution to this problem using some other means. Thanks PS. Please ignore the strange tests. There is a problem with the error handling at the moment.

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• jQuery AJAX chained calls + Celery in Django

  - by user1029968

  Currently clicking one of the links in my application, triggers AJAX call (GET) that - if succeeds - triggers the second one and this second one - if succeeds - calls the third one. This way user can be informed which part of process started when clicking the link is currently ongoing. So in the template file in Django project, click callback body for link mentioned looks like below: $("#the-link").click(function(item)) { // CALL 1 $.ajax({ url: {% url ajax_call_1 %}, data: { // something } }) .done(function(call1Result) { // CALL 2 $.ajax({ url: {% url ajax_call_1 %}, data: { // call1Result passed here to CALL 2 } }) .done(function(call2Result) { // CALL 3 $.ajax({ url: {%url ajax_call_3 %}, data: { // call2Result passed here to CALL 3 } }) .done(function(call3Result) { // expected result if everything went fine console.log("wow, it worked!"); console.log(call3Result); }) .fail(function(errorObject) { console.log("call3 failed"); console.log(errorObject); } }) .fail(function(errorObject)) { console.log("call2 failed"); console.log(errorObject); } }) .fail(function(errorObject) { console.log("call1 failed"); console.log(errorObject); }); }); This works fine for me. The thing is, I'd like to prevent interrupting the following calls if the user closes the browser and the calls are not finished (as it will take some time to finish all three), as there is some additional logic in Django view functions called in each GET request. For example, if user clicks the link and closes the browser during CALL 1, is it possible to somehow go on with the following CALL 2 and CALL 3? I know that normally I'd be able to use Celery Task to process the function but is it still possible here with the chained calls mentioned? Any help is much appreciated!

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• How is this Perl code selecting two different elements from an array?

  - by Mike

  I have inherited some code from a guy whose favorite past time was to shorten every line to its absolute minimum (and sometimes only to make it look cool). His code is hard to understand but I managed to understand (and rewrite) most of it. Now I have stumbled on a piece of code which, no matter how hard I try, I cannot understand. my @heads = grep {s/\.txt$//} OSA::Fast::IO::Ls->ls($SysKey,'fo','osr/tiparlo',qr{^\d+\.txt$}) || (); my @selected_heads = (); for my $i (0..1) { $selected_heads[$i] = int rand scalar @heads; for my $j (0..@heads-1) { last if (!grep $j eq $_, @selected_heads[0..$i-1]); $selected_heads[$i] = ($selected_heads[$i] + 1) % @heads; #WTF? } my $head_nr = sprintf "%04d", $i; OSA::Fast::IO::Cp->cp($SysKey,'',"osr/tiparlo/$heads[$selected_heads[$i]].txt","$recdir/heads/$head_nr.txt"); OSA::Fast::IO::Cp->cp($SysKey,'',"osr/tiparlo/$heads[$selected_heads[$i]].cache","$recdir/heads/$head_nr.cache"); } From what I can understand, this is supposed to be some kind of randomizer, but I never saw a more complex way to achieve randomness. Or are my assumptions wrong? At least, that's what this code is supposed to do. Select 2 random files and copy them. === NOTES === The OSA Framework is a Framework of our own. They are named after their UNIX counterparts and do some basic testing so that the application does not need to bother with that.

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• How to efficiently resize an array of values, without boxing, used within a Dictionary<string, float[]>

  - by makerofthings7

  In the code below, Pages is defined as public SortedDictionary<DateTime, float[]> Pages { get; set; } I am trying to dynamically increase the size of this array. Can anyone tell how to increase the sized of the innermost float[]? var tt = currentContainer.Pages[dateTime]; Array.Resize<float>(ref tt, currentContainer.Pages.Count + 1); Fail 1 I tried the following code and get index out of range exception SortedDictionary<DateTime, float[]> Pages = new SortedDictionary<DateTime,float[]>(); float[] xx = new float[1]; xx[0] = 1; DateTime tempTime = DateTime.UtcNow; Pages.Add(tempTime, xx); var tt = Pages[tempTime]; Array.Resize<float>(ref tt, Pages.Count + 1); Pages[tempTime][1] = 2; Fail 2 The following gives a compile time error (property, index, or dynamic member can't be used as a ref value) SortedDictionary<DateTime, float[]> Pages = new SortedDictionary<DateTime,float[]>(); float[] xx = new float[1]; xx[0] = 1; DateTime tempTime = DateTime.UtcNow; Pages.Add(tempTime, xx); var tt = Pages[tempTime]; // The line below is different from Fail 1 above ... compile time error Array.Resize<float>(ref Pages[tempTime], Pages.Count + 1); Pages[tempTime][1] = 2; Question What is the most performant answer to resize this array? Would the answer change if it's likely that the final size will be 100-200 floats or 700-900 floats? What if I change my allocation size from +1 to +128? .. or larger?

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• i see the file but when i open it nothing is in it in c++ i/o stream and dont know why

  - by user320950

  #include<iostream> #include<fstream> #include<cstdlib> #include<iomanip> using namespace std; int main() { ifstream in_stream; // reads ITEMSLIST.txt ofstream out_stream1; // writes in listWititems.txt ifstream in_stream2; // reads PRICELIST.txt ofstream out_stream3;// writes in listWitprices.txt ifstream in_stream4;// read display.txt ofstream out_stream5;// write showitems.txt double p1=0.0,p2=0.0; int wrong=0; int count =0; char next; in_stream.open("ITEMLIST.txt", ios::in); // list of avaliable items /*if( in_stream.fail() )// check to see if itemlist.txt is open { wrong++; // counts number of errors cout << " the error occured here0, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n" << endl; exit(1); } else{ cout << " System ran correctly " << endl; } */ out_stream1.open("listWititems.txt", ios::out); // list of avaliable items /* if( out_stream1.fail() )// check to see if itemlist.txt is open { wrong++; cout << " the error occured here0, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n" << endl; exit(1); } else{ cout << " System ran correctly " << endl; } */ in_stream2.open("PRICELIST.txt", ios::in); /*if( in_stream2.fail() )// check to see if itemlist.txt is open { wrong++; cout << " the error occured here0, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n" << endl; exit(1); } else{ cout << " System ran correctly " << endl; } */ out_stream3.open("listWitdollars.txt", ios::out); /*if( out_stream3.fail() )// check to see if itemlist.txt is open { wrong++; cout << " the error occured here0, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n" << endl; exit(1); } else{ cout << " System ran correctly " << endl; } */ in_stream4.open("display.txt", ios::in); /*if( in_stream4.fail() )// check to see if itemlist.txt is open { wrong++; cout << " the error occured here0, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n" << endl; exit(1); } else{ cout << " System ran correctly " << endl; } */ out_stream5.open("showitems.txt", ios::out); /*if( out_stream5.fail() )// check to see if itemlist.txt is open { wrong++; cout << " the error occured here0, you have " << wrong++ << " errors" << endl; cout << "Error opening the file\n" << endl; exit(1); } else{ cout << " System ran correctly " << endl; }*/ in_stream.setf(ios::fixed); while(!in_stream.eof()) // reads to end of file and gets p1 which is itemnum, clears and gets next character { in_stream >> p1; cin.clear(); cin >> next; } out_stream1.setf(ios::fixed); while (!out_stream1.eof()) { out_stream1 << p1; cin.clear(); cin >> next; } in_stream2.setf(ios::fixed); in_stream2.setf(ios::showpoint); in_stream2.precision(2); while(!in_stream2.eof()) // reads file to end of file { in_stream2 >> p1 >> p2 >> count; // gets p1,p2, and count which is current total in_stream2 >> p2; p1 += p2; p2++; cin.clear(); // allows more reading cin >> next; return p1, p2; } out_stream3.setf(ios::fixed); out_stream3.setf(ios::showpoint); out_stream3.precision(2); while(!out_stream3.eof()) // reads file to end of file { out_stream3 << p1 << p2 << count; out_stream3 << p2; p1 += p2; p2++; cin.clear(); // allows more reading cin >> next; return p1, p2; } in_stream4.setf(ios::fixed); in_stream4.setf(ios::showpoint); in_stream4.precision(2); while (!in_stream4.eof()) { in_stream4 >> p1 >> p2 >> count; cin.clear(); cin >> next; } out_stream5.setf(ios::fixed); out_stream5.setf(ios::showpoint); out_stream5.precision(2); out_stream5 <<setw(5)<< " itemnum " <<setw(5)<<" price "<<setw(5)<<" curr_total " <<endl; // sends items and prices to receipt.txt out_stream5 << setw(5) << p1 << setw(5) <<p2 << setw(5)<< count; // sends items and prices to receipt.txt out_stream5 << " You have a total of " << wrong++ << " errors " << endl; in_stream.close(); // closing files. out_stream1.close(); in_stream2.close(); out_stream3.close(); in_stream4.close(); out_stream5.close(); system("pause"); }

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• Tools and Utilities for the .NET Developer

  - by mbcrump

  Tweet this list! Add a link to my site to your bookmarks to quickly find this page again! Add me to twitter! This is a list of the tools/utilities that I use to do my job/hobby. I wanted this page to load fast and contain information that only you care about. If I have missed a tool that you like, feel free to contact me and I will add it to the list. Also, this list took a lot of time to complete. Please do not steal my work, if you like the page then please link back to my site. I will keep the links/information updated as new tools/utilities are created.  Windows/.NET Development – This is a list of tools that any Windows/.NET developer should have in his bag. I have used at some point in my career everything listed on this page and below is the tools worth keeping. Name Description License AnkhSVN Subversion support for Visual Studio. It also works with VS2010. Free Aurora XAML Designer One of the best XAML creation tools available. Has a ton of built in templates that you can copy/paste into VS2010. COST/Trial BeyondCompare Beyond Compare 3 is the ideal tool for comparing files and folders on your Windows or Linux system. Visualize changes in your code and carefully reconcile them. COST/Trial BuildIT Automated Task Tool Its main purpose is to automate tasks, whether it is the final packaging of a product, an automated daily build, maybe sending out a mailing list, even backing-up files. Free C Sharper for VB Convert VB to C#. COST CLRProfiler Analyze and improve the behavior of your .NET app. Free CodeRush Direct competitor to ReSharper, contains similar feature. This is one of those decide for yourself. COST/Trial Disk2VHD Disk2vhd is a utility that creates VHD (Virtual Hard Disk - Microsoft's Virtual Machine disk format) versions of physical disks for use in Microsoft Virtual PC or Microsoft Hyper-V virtual machines (VMs). Free Eazfuscator.NET Is a free obfuscator for .NET. The main purpose is to protect intellectual property of software. Free EQATEC Profiler Make your .NET app run faster. No source code changes are needed. Just point the profiler to your app, run the modified code, and get a visual report. COST Expression Studio 3/4 Comes with Web, Blend, Sketch Flow and more. You can create websites, produce beautiful XAML and more. COST/Trial Expresso The award-winning Expresso editor is equally suitable as a teaching tool for the beginning user of regular expressions or as a full-featured development environment for the experienced programmer or web designer with an extensive knowledge of regular expressions. Free Fiddler Fiddler is a web debugging proxy which logs all HTTP(s) traffic between your computer and the internet. Free Firebug Powerful Web development tool. If you build websites, you will need this. Free FxCop FxCop is an application that analyzes managed code assemblies (code that targets the .NET Framework common language runtime) and reports information about the assemblies, such as possible design, localization, performance, and security improvements. Free GAC Browser and Remover Easy way to remove multiple assemblies from the GAC. Assemblies registered by programs like Install Shield can also be removed. Free GAC Util The Global Assembly Cache tool allows you to view and manipulate the contents of the global assembly cache and download cache. Free HelpScribble Help Scribble is a full-featured, easy-to-use help authoring tool for creating help files from start to finish. You can create Win Help (.hlp) files, HTML Help (.chm) files, a printed manual and online documentation (on a web site) all from the same Help Scribble project. COST/Trial IETester IETester is a free Web Browser that allows you to have the rendering and JavaScript engines of IE9 preview, IE8, IE7 IE 6 and IE5.5 on Windows 7, Vista and XP, as well as the installed IE in the same process. Free iTextSharp iText# (iTextSharp) is a port of the iText open source java library for PDF generation written entirely in C# for the .NET platform. Use the iText mailing list to get support. Free Kaxaml Kaxaml is a lightweight XAML editor that gives you a "split view" so you can see both your XAML and your rendered content. Free LINQPad LinqPad lets you interactively query databases in a LINQ. Free Linquer Many programmers are familiar with SQL and will need a help in the transition to LINQ. Sometimes there are complicated queries to be written and Linqer can help by converting SQL scripts to LINQ. COST/Trial LiquidXML Liquid XML Studio 2010 is an advanced XML developers toolkit and IDE, containing all the tools needed for designing and developing XML schema and applications. COST/Trial Log4Net log4net is a tool to help the programmer output log statements to a variety of output targets. log4net is a port of the excellent log4j framework to the .NET runtime. We have kept the framework similar in spirit to the original log4j while taking advantage of new features in the .NET runtime. For more information on log4net see the features document. Free Microsoft Web Platform Installer The Microsoft Web Platform Installer 2.0 (Web PI) is a free tool that makes getting the latest components of the Microsoft Web Platform, including Internet Information Services (IIS), SQL Server Express, .NET Framework and Visual Web Developer easy. Free Mono Development Don't have Visual Studio - no problem! This is an open Source C# and .NET development environment for Linux, Windows, and Mac OS X Free Net Mass Downloader While it’s great that Microsoft has released the .NET Reference Source Code, you can only get it one file at a time while you’re debugging. If you’d like to batch download it for reading or to populate the cache, you’d have to write a program that instantiated and called each method in the Framework Class Library. Fortunately, .NET Mass Downloader comes to the rescue! Free nMap Nmap ("Network Mapper") is a free and open source (license) utility for network exploration or security auditing. Many systems and network administrators also find it useful for tasks such as network inventory, managing service upgrade schedules, and monitoring host or service uptime. Free NoScript (Firefox add-in) The NoScript Firefox extension provides extra protection for Firefox, Flock, Seamonkey and other Mozilla-based browsers: this free, open source add-on allows JavaScript, Java and Flash and other plug-ins to be executed only by trusted web sites of your choice (e.g. your online bank), and provides the most powerful Anti-XSS protection available in a browser. Free NotePad 2 Notepad2, a fast and light-weight Notepad-like text editor with syntax highlighting. This program can be run out of the box without installation, and does not touch your system's registry. Free PageSpy PageSpy is a small add-on for Internet Explorer that allows you to select any element within a webpage, select an option in the context menu, and view detailed information about both the coding behind the page and the element you selected. Free Phrase Express PhraseExpress manages your frequently used text snippets in customizable categories for quick access. Free PowerGui PowerGui is a free community for PowerGUI, a graphical user interface and script editor for Microsoft Windows PowerShell! Free Powershell Comes with Win7, but you can automate tasks by using the .NET Framework. Great for network admins. Free Process Explorer Ever wondered which program has a particular file or directory open? Now you can find out. Process Explorer shows you information about which handles and DLLs processes have opened or loaded. Also, included in the SysInterals Suite. Free Process Monitor Process Monitor is an advanced monitoring tool for Windows that shows real-time file system, Registry and process/thread activity. Free Reflector Explore and analyze compiled .NET assemblies, viewing them in C#, Visual Basic, and IL. This is an Essential for any .NET developer. Free Regular Expression Library Stuck on a Regular Expression but you think someone has already figured it out? Chances are they have. Free Regulator Regulator makes Regular Expressions easy. This is a must have for a .NET Developer. Free RenameMaestro RenameMaestro is probably the easiest batch file renamer you'll find to instantly rename multiple files COST ReSharper The one program that I cannot live without. Supports VS2010 and offers simple refactoring, code analysis/assistance/cleanup/templates. One of the few applications that is worth the $$$. COST/Trial ScrewTurn Wiki ScrewTurn Wiki allows you to create, manage and share wikis. A wiki is a collaboratively-edited, information-centered website: the most famous is Wikipedia. Free SharpDevelop What is #develop? SharpDevelop is a free IDE for C# and VB.NET projects on Microsoft's .NET platform. Free Show Me The Template Show Me The Template is a tool for exploring the templates, be their data, control or items panel, that comes with the controls built into WPF for all 6 themes. Free SnippetCompiler Compiles code snippets without opening Visual Studio. It does not support .NET 4. Free SQL Prompt SQL Prompt is a plug-in that increases how fast you can work with SQL. It provides code-completion for SQL server, reformatting, db schema information and snippets. Awesome! COST/Trial SQLinForm SQLinForm is an automatic SQL code formatter for all major databases  including ORACLE, SQL Server, DB2, UDB, Sybase, Informix, PostgreSQL, Teradata, MySQL, MS Access etc. with over 70 formatting options. COST/OnlineFree SSMS Tools SSMS Tools Pack is an add-in for Microsoft SQL Server Management Studio (SSMS) including SSMS Express. Free Storm STORM is a free and open source tool for testing web services. Free Telerik Code Convertor Convert code from VB to C Sharp and Vice Versa. Free TurtoiseSVN TortoiseSVN is a really easy to use Revision control / version control / source control software for Windows.Since it's not an integration for a specific IDE you can use it with whatever development tools you like. Free UltraEdit UltraEdit is the ideal text, HTML and hex editor, and an advanced PHP, Perl, Java and JavaScript editor for programmers. UltraEdit is also an XML editor including a tree-style XML parser. An industry-award winner, UltraEdit supports disk-based 64-bit file handling (standard) on 32-bit Windows platforms (Windows 2000 and later). COST/Trial Virtual Windows XP Comes with some W7 version and allows you to run WinXP along side W7. Free VirtualBox Virtualization by Sun Microsystems. You can virtualize Windows, Linux and more. Free Visual Log Parser SQL queries against a variety of log files and other system data sources. Free WinMerge WinMerge is an Open Source differencing and merging tool for Windows. WinMerge can compare both folders and files, presenting differences in a visual text format that is easy to understand and handle. Free Wireshark Wireshark is one of the best network protocol analyzer's for Unix and windows. This has been used several times to get me out of a bind. Free XML Notepad 07 Old, but still one of my favorite XML viewers. Free Productivity Tools – This is the list of tools that I use to save time or quickly navigate around Windows. Name Description License AutoHotKey Automate almost anything by sending keystrokes and mouse clicks. You can write a mouse or keyboard macro by hand or use the macro recorder. Free CLCL CLCL is clipboard caching utility. Free Ditto Ditto is an extension to the standard windows clipboard. It saves each item placed on the clipboard allowing you access to any of those items at a later time. Ditto allows you to save any type of information that can be put on the clipboard, text, images, html, custom formats, ..... Free Evernote Remember everything from notes to photos. It will synch between computers/devices. Free InfoRapid Inforapid is a search tool that will display all you search results in a html like browser. If you click on a word in that browser, it will start another search to the word you clicked on. Handy if you want to trackback something to it's true origin. The word you looked for will be highlighted in red. Clicking on the red word will open the containing file in a text based viewer. Clicking on any word in the opened document will start another search on that word. Free KatMouse The prime purpose of the KatMouse utility is to enhance the functionality of mice with a scroll wheel, offering 'universal' scrolling: moving the mouse wheel will scroll the window directly beneath the mouse cursor (not the one with the keyboard focus, which is default on Windows OSes). This is a major increase in the usefulness of the mouse wheel. Free ScreenR Instant Screencast with nothing to download. Works with Mac or PC and free. Free Start++ Start++ is an enhancement for the Start Menu in Windows Vista. It also extends the Run box and the command-line with customizable commands.  For example, typing "w Windows Vista" will take you to the Windows Vista page on Wikipedia! Free Synergy Synergy lets you easily share a single mouse and keyboard between multiple computers with different operating systems, each with its own display, without special hardware. It's intended for users with multiple computers on their desk since each system uses its own monitor(s). Free Texter Texter lets you define text substitution hot strings that, when triggered, will replace hotstring with a larger piece of text. By entering your most commonly-typed snippets of text into Texter, you can save countless keystrokes in the course of the day. Free Total Commander File handling, FTP, Archive handling and much more. Even works with Win3.11. COST/Trial Available Wizmouse WizMouse is a mouse enhancement utility that makes your mouse wheel work on the window currently under the mouse pointer, instead of the currently focused window. This means you no longer have to click on a window before being able to scroll it with the mouse wheel. This is a far more comfortable and practical way to make use of the mouse wheel. Free Xmarks Bookmark sync and search between computers. Free General Utilities – This is a list for power user users or anyone that wants more out of Windows. I usually install a majority of these whenever I get a new system. Name Description License µTorrent µTorrent is a lightweight and efficient BitTorrent client for Windows or Mac with many features. I use this for downloading LEGAL media. Free Audacity Audacity® is free, open source software for recording and editing sounds. It is available for Mac OS X, Microsoft Windows, GNU/Linux, and other operating systems. Learn more about Audacity... Also check our Wiki and Forum for more information. Free AVast Free FREE Antivirus. Free CD Burner XP Pro CDBurnerXP is a free application to burn CDs and DVDs, including Blu-Ray and HD-DVDs. It also includes the feature to burn and create ISOs, as well as a multilanguage interface. Free CDEX You can extract digital audio CDs into mp3/wav. Free Combofix Combofix is a freeware (a legitimate spyware remover created by sUBs), Combofix was designed to scan a computer for known malware, spyware (SurfSideKick, QooLogic, and Look2Me as well as any other combination of the mentioned spyware applications) and remove them. Free Cpu-Z Provides information about some of the main devices of your system. Free Cropper Cropper is a screen capture utility written in C#. It makes it fast and easy to grab parts of your screen. Use it to easily crop out sections of vector graphic files such as Fireworks without having to flatten the files or open in a new editor. Use it to easily capture parts of a web site, including text and images. It's also great for writing documentation that needs images of your application or web site. Free DropBox Drag and Drop files to sync between computers. Free DVD-Fab Converts/Copies DVDs/Blu-Ray to different formats. (like mp4, mkv, avi) COST/Trial Available FastStone Capture FastStone Capture is a powerful, lightweight, yet full-featured screen capture tool that allows you to easily capture and annotate anything on the screen including windows, objects, menus, full screen, rectangular/freehand regions and even scrolling windows/web pages. Free ffdshow FFDShow is a DirectShow decoding filter for decompressing DivX, XviD, H.264, FLV1, WMV, MPEG-1 and MPEG-2, MPEG-4 movies. Free Filezilla FileZilla Client is a fast and reliable cross-platform FTP, FTPS and SFTP client with lots of useful features and an intuitive graphical user interface. You can also download a server version. Free FireFox Web Browser, do you really need an explanation? Free FireGestures A customizable mouse gestures extension which enables you to execute various commands and user scripts with five types of gestures. Free FoxIt Reader Light weight PDF viewer. You should install this with the advanced setting or it will install a toolbar and setup some shortcuts. Free gSynchIt Synch Gmail and Outlook. Even supports Outlook 2010 32/64 bit COST/Trial Available Hulu Desktop At home or in a hotel, this has replaced my cable/satellite subscription. Free ImgBurn ImgBurn is a lightweight CD / DVD / HD DVD / Blu-ray burning application that everyone should have in their toolkit! Free Infrarecorder InfraRecorder is a free CD/DVD burning solution for Microsoft Windows. It offers a wide range of powerful features; all through an easy to use application interface and Windows Explorer integration. Free KeePass KeePass is a free open source password manager, which helps you to manage your passwords in a secure way. Free LastPass Another password management, synchronize between browsers, automatic form filling and more. Free Live Essentials One download and lots of programs including Mail, Live Writer, Movie Maker and more! Free Monitores MonitorES is a small windows utility that helps you to turnoff monitor display when you lock down your machine.Also when you lock your machine, it will pause all your running media programs & set your IM status message to "Away" / Custom message(via options) and restore it back to normal when you back. Free mRemote mRemote is a full-featured, multi-tab remote connections manager. Free Open Office OpenOffice.org 3 is the leading open-source office software suite for word processing, spreadsheets, presentations, graphics, databases and more. It is available in many languages and works on all common computers. It stores all your data in an international open standard format and can also read and write files from other common office software packages. It can be downloaded and used completely free of charge for any purpose. Free Paint.NET Simple, intuitive, and innovative user interface for editing photos. Free Picasa Picasa is free photo editing software from Google that makes your pictures look great. Free Pidgin Pidgin is an easy to use and free chat client used by millions. Connect to AIM, MSN, Yahoo, and more chat networks all at once. Free PING PING is a live Linux ISO, based on the excellent Linux From Scratch (LFS) documentation. It can be burnt on a CD and booted, or integrated into a PXE / RIS environment. Free Putty PuTTY is an SSH and telnet client, developed originally by Simon Tatham for the Windows platform. Free Revo Uninstaller Revo Uninstaller Pro helps you to uninstall software and remove unwanted programs installed on your computer easily! Even if you have problems uninstalling and cannot uninstall them from "Windows Add or Remove Programs" control panel applet.Revo Uninstaller is a much faster and more powerful alternative to "Windows Add or Remove Programs" applet! It has very powerful features to uninstall and remove programs. Free Security Essentials Microsoft Security Essentials is a new, free consumer anti-malware solution for your computer. Free SetupVirtualCloneDrive Virtual CloneDrive works and behaves just like a physical CD/DVD drive, however it exists only virtually. Point to the .ISO file and it appears in Windows Explorer as a Drive. Free Shark 007 Codec Pack Play just about any file format with this download. Also includes my W7 Media Playlist Generator. Free Snagit 9 Screen Capture on steroids. Add arrows, captions, etc to any screenshot. COST/Trial Available SysinternalsSuite Go ahead and download the entire sys internals suite. I have mentioned multiple programs in this suite already. Free TeraCopy TeraCopy is a compact program designed to copy and move files at the maximum possible speed, providing the user with a lot of features. Free for Home TrueCrypt Free open-source disk encryption software for Windows 7/Vista/XP, Mac OS X, and Linux Free TweetDeck Fully featured Twitter client. Free UltraVNC UltraVNC is a powerful, easy to use and free software that can display the screen of another computer (via internet or network) on your own screen. The program allows you to use your mouse and keyboard to control the other PC remotely. It means that you can work on a remote computer, as if you were sitting in front of it, right from your current location. Free Unlocker Unlocks locked files. Pretty simple right? Free VLC Media Player VLC media player is a highly portable multimedia player and multimedia framework capable of reading most audio and video formats Free Windows 7 Media Playlist This program is special to my heart because I wrote it. It has been mentioned on podcast and various websites. It allows you to quickly create wvx video playlist for Windows Media Center. Free WinRAR WinRAR is a powerful archive manager. It can backup your data and reduce the size of email attachments, decompress RAR, ZIP and other files downloaded from Internet and create new archives in RAR and ZIP file format. COST/Trial Available Blogging – I use the following for my blog. Name Description License Insert Code for Windows Live Writer Insert Code for Windows Live Writer will format a snippet of text in a number of programming languages such as C#, HTML, MSH, JavaScript, Visual Basic and TSQL. Free LiveWriter Included in Live Essentials, but the ultimate in Windows Blogging Free PasteAsVSCode Plug-in for Windows Live Writer that pastes clipboard content as Visual Studio code. Preserves syntax highlighting, indentation and background color. Converts RTF, outputted by Visual Studio, into HTML. Free Desktop Management – The list below represent the best in Windows Desktop Management. Name Description License 7 Stacks Allows users to have "stacks" of icons in their taskbar. Free Executor Executor is a multi purpose launcher and a more advanced and customizable version of windows run. Free Fences Fences is a program that helps you organize your desktop and can hide your icons when they are not in use. Free RocketDock Rocket Dock is a smoothly animated, alpha blended application launcher. It provides a nice clean interface to drop shortcuts on for easy access and organization. With each item completely customizable there is no end to what you can add and launch from the dock. Free WindowsTab Tabbing is an essential feature of modern web browsers. Window Tabs brings the productivity of tabbed window management to all of your desktop applications. Free

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• How to find and fix performance problems in ORM powered applications

  - by FransBouma

  Once in a while we get requests about how to fix performance problems with our framework. As it comes down to following the same steps and looking into the same things every single time, I decided to write a blogpost about it instead, so more people can learn from this and solve performance problems in their O/R mapper powered applications. In some parts it's focused on LLBLGen Pro but it's also usable for other O/R mapping frameworks, as the vast majority of performance problems in O/R mapper powered applications are not specific for a certain O/R mapper framework. Too often, the developer looks at the wrong part of the application, trying to fix what isn't a problem in that part, and getting frustrated that 'things are so slow with <insert your favorite framework X here>'. I'm in the O/R mapper business for a long time now (almost 10 years, full time) and as it's a small world, we O/R mapper developers know almost all tricks to pull off by now: we all know what to do to make task ABC faster and what compromises (because there are almost always compromises) to deal with if we decide to make ABC faster that way. Some O/R mapper frameworks are faster in X, others in Y, but you can be sure the difference is mainly a result of a compromise some developers are willing to deal with and others aren't. That's why the O/R mapper frameworks on the market today are different in many ways, even though they all fetch and save entities from and to a database. I'm not suggesting there's no room for improvement in today's O/R mapper frameworks, there always is, but it's not a matter of 'the slowness of the application is caused by the O/R mapper' anymore. Perhaps query generation can be optimized a bit here, row materialization can be optimized a bit there, but it's mainly coming down to milliseconds. Still worth it if you're a framework developer, but it's not much compared to the time spend inside databases and in user code: if a complete fetch takes 40ms or 50ms (from call to entity object collection), it won't make a difference for your application as that 10ms difference won't be noticed. That's why it's very important to find the real locations of the problems so developers can fix them properly and don't get frustrated because their quest to get a fast, performing application failed. Performance tuning basics and rules Finding and fixing performance problems in any application is a strict procedure with four prescribed steps: isolate, analyze, interpret and fix, in that order. It's key that you don't skip a step nor make assumptions: these steps help you find the reason of a problem which seems to be there, and how to fix it or leave it as-is. Skipping a step, or when you assume things will be bad/slow without doing analysis will lead to the path of premature optimization and won't actually solve your problems, only create new ones. The most important rule of finding and fixing performance problems in software is that you have to understand what 'performance problem' actually means. Most developers will say "when a piece of software / code is slow, you have a performance problem". But is that actually the case? If I write a Linq query which will aggregate, group and sort 5 million rows from several tables to produce a resultset of 10 rows, it might take more than a couple of milliseconds before that resultset is ready to be consumed by other logic. If I solely look at the Linq query, the code consuming the resultset of the 10 rows and then look at the time it takes to complete the whole procedure, it will appear to me to be slow: all that time taken to produce and consume 10 rows? But if you look closer, if you analyze and interpret the situation, you'll see it does a tremendous amount of work, and in that light it might even be extremely fast. With every performance problem you encounter, always do realize that what you're trying to solve is perhaps not a technical problem at all, but a perception problem. The second most important rule you have to understand is based on the old saying "Penny wise, Pound Foolish": the part which takes e.g. 5% of the total time T for a given task isn't worth optimizing if you have another part which takes a much larger part of the total time T for that same given task. Optimizing parts which are relatively insignificant for the total time taken is not going to bring you better results overall, even if you totally optimize that part away. This is the core reason why analysis of the complete set of application parts which participate in a given task is key to being successful in solving performance problems: No analysis -> no problem -> no solution. One warning up front: hunting for performance will always include making compromises. Fast software can be made maintainable, but if you want to squeeze as much performance out of your software, you will inevitably be faced with the dilemma of compromising one or more from the group {readability, maintainability, features} for the extra performance you think you'll gain. It's then up to you to decide whether it's worth it. In almost all cases it's not. The reason for this is simple: the vast majority of performance problems can be solved by implementing the proper algorithms, the ones with proven Big O-characteristics so you know the performance you'll get plus you know the algorithm will work. The time taken by the algorithm implementing code is inevitable: you already implemented the best algorithm. You might find some optimizations on the technical level but in general these are minor. Let's look at the four steps to see how they guide us through the quest to find and fix performance problems. Isolate The first thing you need to do is to isolate the areas in your application which are assumed to be slow. For example, if your application is a web application and a given page is taking several seconds or even minutes to load, it's a good candidate to check out. It's important to start with the isolate step because it allows you to focus on a single code path per area with a clear begin and end and ignore the rest. The rest of the steps are taken per identified problematic area. Keep in mind that isolation focuses on tasks in an application, not code snippets. A task is something that's started in your application by either another task or the user, or another program, and has a beginning and an end. You can see a task as a piece of functionality offered by your application.  Analyze Once you've determined the problem areas, you have to perform analysis on the code paths of each area, to see where the performance problems occur and which areas are not the problem. This is a multi-layered effort: an application which uses an O/R mapper typically consists of multiple parts: there's likely some kind of interface (web, webservice, windows etc.), a part which controls the interface and business logic, the O/R mapper part and the RDBMS, all connected with either a network or inter-process connections provided by the OS or other means. Each of these parts, including the connectivity plumbing, eat up a part of the total time it takes to complete a task, e.g. load a webpage with all orders of a given customer X. To understand which parts participate in the task / area we're investigating and how much they contribute to the total time taken to complete the task, analysis of each participating task is essential. Start with the code you wrote which starts the task, analyze the code and track the path it follows through your application. What does the code do along the way, verify whether it's correct or not. Analyze whether you have implemented the right algorithms in your code for this particular area. Remember we're looking at one area at a time, which means we're ignoring all other code paths, just the code path of the current problematic area, from begin to end and back. Don't dig in and start optimizing at the code level just yet. We're just analyzing. If your analysis reveals big architectural stupidity, it's perhaps a good idea to rethink the architecture at this point. For the rest, we're analyzing which means we collect data about what could be wrong, for each participating part of the complete application. Reviewing the code you wrote is a good tool to get deeper understanding of what is going on for a given task but ultimately it lacks precision and overview what really happens: humans aren't good code interpreters, computers are. We therefore need to utilize tools to get deeper understanding about which parts contribute how much time to the total task, triggered by which other parts and for example how many times are they called. There are two different kind of tools which are necessary: .NET profilers and O/R mapper / RDBMS profilers. .NET profiling .NET profilers (e.g. dotTrace by JetBrains or Ants by Red Gate software) show exactly which pieces of code are called, how many times they're called, and the time it took to run that piece of code, at the method level and sometimes even at the line level. The .NET profilers are essential tools for understanding whether the time taken to complete a given task / area in your application is consumed by .NET code, where exactly in your code, the path to that code, how many times that code was called by other code and thus reveals where hotspots are located: the areas where a solution can be found. Importantly, they also reveal which areas can be left alone: remember our penny wise pound foolish saying: if a profiler reveals that a group of methods are fast, or don't contribute much to the total time taken for a given task, ignore them. Even if the code in them is perhaps complex and looks like a candidate for optimization: you can work all day on that, it won't matter.  As we're focusing on a single area of the application, it's best to start profiling right before you actually activate the task/area. Most .NET profilers support this by starting the application without starting the profiling procedure just yet. You navigate to the particular part which is slow, start profiling in the profiler, in your application you perform the actions which are considered slow, and afterwards you get a snapshot in the profiler. The snapshot contains the data collected by the profiler during the slow action, so most data is produced by code in the area to investigate. This is important, because it allows you to stay focused on a single area. O/R mapper and RDBMS profiling .NET profilers give you a good insight in the .NET side of things, but not in the RDBMS side of the application. As this article is about O/R mapper powered applications, we're also looking at databases, and the software making it possible to consume the database in your application: the O/R mapper. To understand which parts of the O/R mapper and database participate how much to the total time taken for task T, we need different tools. There are two kind of tools focusing on O/R mappers and database performance profiling: O/R mapper profilers and RDBMS profilers. For O/R mapper profilers, you can look at LLBLGen Prof by hibernating rhinos or the Linq to Sql/LLBLGen Pro profiler by Huagati. Hibernating rhinos also have profilers for other O/R mappers like NHibernate (NHProf) and Entity Framework (EFProf) and work the same as LLBLGen Prof. For RDBMS profilers, you have to look whether the RDBMS vendor has a profiler. For example for SQL Server, the profiler is shipped with SQL Server, for Oracle it's build into the RDBMS, however there are also 3rd party tools. Which tool you're using isn't really important, what's important is that you get insight in which queries are executed during the task / area we're currently focused on and how long they took. Here, the O/R mapper profilers have an advantage as they collect the time it took to execute the query from the application's perspective so they also collect the time it took to transport data across the network. This is important because a query which returns a massive resultset or a resultset with large blob/clob/ntext/image fields takes more time to get transported across the network than a small resultset and a database profiler doesn't take this into account most of the time. Another tool to use in this case, which is more low level and not all O/R mappers support it (though LLBLGen Pro and NHibernate as well do) is tracing: most O/R mappers offer some form of tracing or logging system which you can use to collect the SQL generated and executed and often also other activity behind the scenes. While tracing can produce a tremendous amount of data in some cases, it also gives insight in what's going on. Interpret After we've completed the analysis step it's time to look at the data we've collected. We've done code reviews to see whether we've done anything stupid and which parts actually take place and if the proper algorithms have been implemented. We've done .NET profiling to see which parts are choke points and how much time they contribute to the total time taken to complete the task we're investigating. We've performed O/R mapper profiling and RDBMS profiling to see which queries were executed during the task, how many queries were generated and executed and how long they took to complete, including network transportation. All this data reveals two things: which parts are big contributors to the total time taken and which parts are irrelevant. Both aspects are very important. The parts which are irrelevant (i.e. don't contribute significantly to the total time taken) can be ignored from now on, we won't look at them. The parts which contribute a lot to the total time taken are important to look at. We now have to first look at the .NET profiler results, to see whether the time taken is consumed in our own code, in .NET framework code, in the O/R mapper itself or somewhere else. For example if most of the time is consumed by DbCommand.ExecuteReader, the time it took to complete the task is depending on the time the data is fetched from the database. If there was just 1 query executed, according to tracing or O/R mapper profilers / RDBMS profilers, check whether that query is optimal, uses indexes or has to deal with a lot of data. Interpret means that you follow the path from begin to end through the data collected and determine where, along the path, the most time is contributed. It also means that you have to check whether this was expected or is totally unexpected. My previous example of the 10 row resultset of a query which groups millions of rows will likely reveal that a long time is spend inside the database and almost no time is spend in the .NET code, meaning the RDBMS part contributes the most to the total time taken, the rest is compared to that time, irrelevant. Considering the vastness of the source data set, it's expected this will take some time. However, does it need tweaking? Perhaps all possible tweaks are already in place. In the interpret step you then have to decide that further action in this area is necessary or not, based on what the analysis results show: if the analysis results were unexpected and in the area where the most time is contributed to the total time taken is room for improvement, action should be taken. If not, you can only accept the situation and move on. In all cases, document your decision together with the analysis you've done. If you decide that the perceived performance problem is actually expected due to the nature of the task performed, it's essential that in the future when someone else looks at the application and starts asking questions you can answer them properly and new analysis is only necessary if situations changed. Fix After interpreting the analysis results you've concluded that some areas need adjustment. This is the fix step: you're actively correcting the performance problem with proper action targeted at the real cause. In many cases related to O/R mapper powered applications it means you'll use different features of the O/R mapper to achieve the same goal, or apply optimizations at the RDBMS level. It could also mean you apply caching inside your application (compromise memory consumption over performance) to avoid unnecessary re-querying data and re-consuming the results. After applying a change, it's key you re-do the analysis and interpretation steps: compare the results and expectations with what you had before, to see whether your actions had any effect or whether it moved the problem to a different part of the application. Don't fall into the trap to do partly analysis: do the full analysis again: .NET profiling and O/R mapper / RDBMS profiling. It might very well be that the changes you've made make one part faster but another part significantly slower, in such a way that the overall problem hasn't changed at all. Performance tuning is dealing with compromises and making choices: to use one feature over the other, to accept a higher memory footprint, to go away from the strict-OO path and execute queries directly onto the RDBMS, these are choices and compromises which will cross your path if you want to fix performance problems with respect to O/R mappers or data-access and databases in general. In most cases it's not a big issue: alternatives are often good choices too and the compromises aren't that hard to deal with. What is important is that you document why you made a choice, a compromise: which analysis data, which interpretation led you to the choice made. This is key for good maintainability in the years to come. Most common performance problems with O/R mappers Below is an incomplete list of common performance problems related to data-access / O/R mappers / RDBMS code. It will help you with fixing the hotspots you found in the interpretation step. SELECT N+1: (Lazy-loading specific). Lazy loading triggered performance bottlenecks. Consider a list of Orders bound to a grid. You have a Field mapped onto a related field in Order, Customer.CompanyName. Showing this column in the grid will make the grid fetch (indirectly) for each row the Customer row. This means you'll get for the single list not 1 query (for the orders) but 1+(the number of orders shown) queries. To solve this: use eager loading using a prefetch path to fetch the customers with the orders. SELECT N+1 is easy to spot with an O/R mapper profiler or RDBMS profiler: if you see a lot of identical queries executed at once, you have this problem. Prefetch paths using many path nodes or sorting, or limiting. Eager loading problem. Prefetch paths can help with performance, but as 1 query is fetched per node, it can be the number of data fetched in a child node is bigger than you think. Also consider that data in every node is merged on the client within the parent. This is fast, but it also can take some time if you fetch massive amounts of entities. If you keep fetches small, you can use tuning parameters like the ParameterizedPrefetchPathThreshold setting to get more optimal queries. Deep inheritance hierarchies of type Target Per Entity/Type. If you use inheritance of type Target per Entity / Type (each type in the inheritance hierarchy is mapped onto its own table/view), fetches will join subtype- and supertype tables in many cases, which can lead to a lot of performance problems if the hierarchy has many types. With this problem, keep inheritance to a minimum if possible, or switch to a hierarchy of type Target Per Hierarchy, which means all entities in the inheritance hierarchy are mapped onto the same table/view. Of course this has its own set of drawbacks, but it's a compromise you might want to take. Fetching massive amounts of data by fetching large lists of entities. LLBLGen Pro supports paging (and limiting the # of rows returned), which is often key to process through large sets of data. Use paging on the RDBMS if possible (so a query is executed which returns only the rows in the page requested). When using paging in a web application, be sure that you switch server-side paging on on the datasourcecontrol used. In this case, paging on the grid alone is not enough: this can lead to fetching a lot of data which is then loaded into the grid and paged there. Keep note that analyzing queries for paging could lead to the false assumption that paging doesn't occur, e.g. when the query contains a field of type ntext/image/clob/blob and DISTINCT can't be applied while it should have (e.g. due to a join): the datareader will do DISTINCT filtering on the client. this is a little slower but it does perform paging functionality on the data-reader so it won't fetch all rows even if the query suggests it does. Fetch massive amounts of data because blob/clob/ntext/image fields aren't excluded. LLBLGen Pro supports field exclusion for queries. You can exclude fields (also in prefetch paths) per query to avoid fetching all fields of an entity, e.g. when you don't need them for the logic consuming the resultset. Excluding fields can greatly reduce the amount of time spend on data-transport across the network. Use this optimization if you see that there's a big difference between query execution time on the RDBMS and the time reported by the .NET profiler for the ExecuteReader method call. Doing client-side aggregates/scalar calculations by consuming a lot of data. If possible, try to formulate a scalar query or group by query using the projection system or GetScalar functionality of LLBLGen Pro to do data consumption on the RDBMS server. It's far more efficient to process data on the RDBMS server than to first load it all in memory, then traverse the data in-memory to calculate a value. Using .ToList() constructs inside linq queries. It might be you use .ToList() somewhere in a Linq query which makes the query be run partially in-memory. Example: var q = from c in metaData.Customers.ToList() where c.Country=="Norway" select c; This will actually fetch all customers in-memory and do an in-memory filtering, as the linq query is defined on an IEnumerable<T>, and not on the IQueryable<T>. Linq is nice, but it can often be a bit unclear where some parts of a Linq query might run. Fetching all entities to delete into memory first. To delete a set of entities it's rather inefficient to first fetch them all into memory and then delete them one by one. It's more efficient to execute a DELETE FROM ... WHERE query on the database directly to delete the entities in one go. LLBLGen Pro supports this feature, and so do some other O/R mappers. It's not always possible to do this operation in the context of an O/R mapper however: if an O/R mapper relies on a cache, these kind of operations are likely not supported because they make it impossible to track whether an entity is actually removed from the DB and thus can be removed from the cache. Fetching all entities to update with an expression into memory first. Similar to the previous point: it is more efficient to update a set of entities directly with a single UPDATE query using an expression instead of fetching the entities into memory first and then updating the entities in a loop, and afterwards saving them. It might however be a compromise you don't want to take as it is working around the idea of having an object graph in memory which is manipulated and instead makes the code fully aware there's a RDBMS somewhere. Conclusion Performance tuning is almost always about compromises and making choices. It's also about knowing where to look and how the systems in play behave and should behave. The four steps I provided should help you stay focused on the real problem and lead you towards the solution. Knowing how to optimally use the systems participating in your own code (.NET framework, O/R mapper, RDBMS, network/services) is key for success as well as knowing what's going on inside the application you built. I hope you'll find this guide useful in tracking down performance problems and dealing with them in a useful way.  

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• OpenVPN slow with Firewall enabled on Zyxel ZyWall USG-100

  - by aleroot

  I have an OpenVPN server on a Linux machine, after installing a ZyWall USG-100 I'm experiencing extremely slowness navigating web servers on my remote LAN through the VPN connection, while accessing the web interface of the ZyWall is fast. I have configured everything : the Virtual Server for the OpenVPN Server, the static route as with the replaced router that I had before installing the ZyWall Today. I even added a rule to the firewall that allows connection to the OpenVPN Server machine : but navigation on the LAN through the VPN still slow, it seems that the Firewall is blocking packages, since if I disable the firewall on the USG-100 everything works fast as usual, while with the firewall enabled it is extremely slow. Why ? Do I need to add some other rule to the firewall to speed up ?

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• many partitions on a single filegroup?¿ does it make sense?

  - by river0

  Hi, I'm designing a datawarehouse solution and I'm a newbie in disk configuration issues, let me explain you. Our storage is spread over 6 storage enlosures having each of them 5 raid-1 disk arrays, and having 2 LUNS defined per each disk array, which makes a total 48 LUNS (this is following Microsoft fast track recommendations for datawarehouse architectures). I would like to partition my data, on other projects I have worked before, we always followed a 1 partition - 1 filegroup rule. On the microsoft fast track recomendations it is advised to create a filegroup and then for that filegroup a data file per each lun... but I pretend to have a week level partitioning... if I apply that rule I think that I'll get too many files and a complex layout. I'm thinking of just creating just one filegroup (with the 48 lun data files), but still create the partitions since I want to keep soem of the benefits of partitions like partition switching... Is this scenario not recommended? What would you suggest?

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• Parallel prologue and epilogue in Grid Engine

  - by ajdecon

  We have a cluster being used to run MPI jobs for a customer. Previously this cluster used Torque as the scheduler, but we are transitioning to Grid Engine 6.2u5 (for some other features). Unfortunately, we are having trouble duplicating some of our maintenance scripts in the Grid Engine environment. In Torque, we have a prologue.parallel script which is used to carry out an automated health-check on the node. If this script returns a fail condition, Torque will helpfully offline the node and re-queue the job to use a different group of nodes. In Grid Engine, however, the queue "prolog" only runs on the head node of the job. We can manually run our prologue script from the startmpi.sh initialization script, for the mpi parallel environment; but I can't figure out how to detect a fail condition and carry out the same "mark offline and requeue" procedure. Any suggestions?

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• WD1000FYPS harddrive is marked 0 mb in 3ware (and no SMART)

  - by osgx

  After reboot my SATA 1TB WD1000FYPS (previously is was "Drive error") is marked 0 mb in 3ware web gui. Complete message: Available Drives (Controller ID 0) Port 1 WDC WD1000FYPS-01ZKB0 0.00 MB NOT SUPPORTED [Remove Drive] SMART gives me only Device Model and ATA protocol version 1 (not 7-8 as it must be for SATA) What does it mean? Just before reboot, when is was marked only with "Device Error", smart was: Device Model: WDC WD1000FYPS-01ZKB0 Serial Number: WD-WCASJ1130*** Firmware Version: 02.01B01 User Capacity: 1,000,204,886,016 bytes Device is: Not in smartctl database [for details use: -P showall] ATA Version is: 8 ATA Standard is: Exact ATA specification draft version not indicated Local Time is: Sun Mar 7 18:47:35 2010 MSK SMART support is: Available - device has SMART capability. SMART support is: Enabled SMART overall-health self-assessment test result: PASSED SMART Attributes Data Structure revision number: 16 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x000f 200 200 051 Pre-fail Always - 0 3 Spin_Up_Time 0x0003 188 186 021 Pre-fail Always - 7591 4 Start_Stop_Count 0x0032 100 100 000 Old_age Always - 229 5 Reallocated_Sector_Ct 0x0033 199 199 140 Pre-fail Always - 3 7 Seek_Error_Rate 0x000e 193 193 000 Old_age Always - 125 9 Power_On_Hours 0x0032 078 078 000 Old_age Always - 16615 10 Spin_Retry_Count 0x0012 100 100 000 Old_age Always - 0 11 Calibration_Retry_Count 0x0012 100 253 000 Old_age Always - 0 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 77 192 Power-Off_Retract_Count 0x0032 198 198 000 Old_age Always - 1564 193 Load_Cycle_Count 0x0032 146 146 000 Old_age Always - 164824 194 Temperature_Celsius 0x0022 117 100 000 Old_age Always - 35 196 Reallocated_Event_Count 0x0032 199 199 000 Old_age Always - 1 197 Current_Pending_Sector 0x0012 200 200 000 Old_age Always - 0 198 Offline_Uncorrectable 0x0010 200 200 000 Old_age Offline - 0 199 UDMA_CRC_Error_Count 0x003e 200 200 000 Old_age Always - 0 200 Multi_Zone_Error_Rate 0x0008 200 200 000 Old_age Offline - 0 What can be wrong with he? Can it be restored? PS new smart is === START OF INFORMATION SECTION === Device Model: WDC WD1000FYPS-01ZKB0 Serial Number: [No Information Found] Firmware Version: [No Information Found] Device is: Not in smartctl database [for details use: -P showall] ATA Version is: 1 ATA Standard is: Exact ATA specification draft version not indicated Local Time is: Mon Mar 8 00:29:44 2010 MSK SMART is only available in ATA Version 3 Revision 3 or greater. We will try to proceed in spite of this. SMART support is: Ambiguous - ATA IDENTIFY DEVICE words 82-83 don't show if SMART supported. Checking for SMART support by trying SMART ENABLE command. Command failed, ata.status=(0x00), ata.command=(0x51), ata.flags=(0x01) Error SMART Enable failed: Input/output error SMART ENABLE failed - this establishes that this device lacks SMART functionality. A mandatory SMART command failed: exiting. To continue, add one or more '-T permissive' options. PPS There was a rapid grow of " 192 Power-Off_Retract_Count " before dying. The hard was used in raid, with several hards from the same fabric packaging box (close id's). The hard drives were placed identically. Rapid means almost linear grow from 300 to 1700 in 6-7 hours. Maximal temperature was 41C. (thanks to munin's smart monitoring)

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