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• Problem using SQLDMO/Vb6 against SQL Server 2008

  - by E.J. Brennan

  I have a client, that uses SQLDMO for a portion of a custom application that was written against SQL Server 2000, and they recently upgraded to SQL Server 2008. The majority of the app still runs fine (doesn't use SQLDMO), but the admin functions which rely on SQLDMO stopped working. I installed the SQL2005 backward compatibility pack, and now SQLDMO partially works, i.e. I can run "select" type queries, but any "Update" queries fail with the error message: to connect to the server you must use SQL Server management studio or sql server management objects (SMO) Any thoughts? Should the backward compatibility pack give me ALL the functionality back, or is this a known issue? BTW: I realize SQLDMO has been deprecated and will go away next release, none-the-less I need to do what I can to solve the problem at hand.

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• Best Data Structure For Time Series Data

  - by TriParkinson

  Hi all, I wonder if someone could take a minute out of their day to give their two cents on my problem. I would like some suggestions on what would be the best data structure for representing, on disk, a large data set of time series data. The main priority is speed of insertion, with other priorities in decreasing order; speed of retrieval, size on disk, size in memory, speed of removal. I have seen that B+ trees are often used in database because of their fast search times, but how about for fast insertion times? Is a linked list really the way to go? Thanks in advance for your time, Tri

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• algorithm diagram

  - by tunl

  This is the max searching algorithm diagram: So, I wonder how can draw diagram for Recursion in HaNoi Tower program: package tunl; public class TowersApp { static int n = 3; public static void main(String[] args) { TowersApp.doTowers(3, 'A', 'B', 'C'); } public static void doTowers(int n, char from, char inter, char to) { if (n == 1) { System.out.println("disk 1 from "+ from + " to " + to); } else { doTowers(n-1, from, to, inter); System.out.println("disk " + n + " from " + from + " to " + to); doTowers(n-1, inter, from, to); } } } I can't draw it. Anyone can help me !!!

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• Partial sorting algorithm

  - by Enriquev

  Hello, Say I have 50 million features, each feature comes from disk. At the beggining of my program, I handle each feature and depending on some conditions, I apply some modifications to some. A this point in my program, I am reading a feature from disk, processing it, and writing it back, because well I don't have enough ram to open all 50 million features at once. Now say I want to sort these 50 million features, is there any optimal algorithm to do this as I can't load everyone at the same time? Like a partial sorting algorithm or something like that?

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• Somebody is storing credit card data - how are they doing it?

  - by pygorex1

  Storing credit card information securely and legally is very difficult and should not be attempted. I have no intention of storing credit card data but I'm dying to figure out the following: My credit card info is being stored on a server some where in he tworld. This data is (hopefully) not being stored on a merchant's server, but at some point it needs to be stored to verify and charge the account identified by merchant submitted data. My question is this: if you were tasked with storing credit card data what encryption strategy would you use to secure the data on-disk? From what I can tell submitted credit card info is being checked more or less in real time. I doubt that any encryption key used to secure the data is being entered manually, so decryption is being done on the fly, which implies that the keys themselves are being stored on-disk. How would you secure your data and your keys in an automated system like this?

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• what special issues are at play when loading a config file from the comand prompt with DTExec

  - by Ralph Shillington

  If I run a package from the Management Studio, and specify a configuration file, everything works as expected. However if I try and run the package from the command prompt with DTExec I get the error: Cannot load the XML configuration file. The XML configuration file may be malformed or not valid. The command I'm using to execute the package is: dtexec /conf ConfigurationDemo.dtsConfig /f Package.dtsx I am running the dtexec from the folder where these two files reside. Is there an addtional switch or something that must used to get dtexec to behave the same was at the management Stduio in launching a package?

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• read url in binary mode in java

  - by Andrew Zawok

  In java I need to read a binary file from a site and write it to a disk file. This example http://java.sun.com/docs/books/tutorial/networking/urls/readingURL.html could read webpages succesfully, but when I try to read a binary file from my localhost server and write it to a disk file the contents change, corrupting the binary file. Using fc I see that 0x90 is changed to 0x3F and other changes. How do I acess the binary files (read url and write to file) without java or anything else changing ANY characters, like doing any newline conversions or character conversions or anything else, simply reading input url and writing it out as a file.

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• Sybase IQ: How to create a DBSPACE with raw device?

  - by Martin Klier

  I try to add a dbspace to a demo database, using a raw device on Linux. I always get SQL error 1010000, file already exists: CREATE DBSPACE KLMTEST USING FILE DF1 '/dev/disk/by-id/scsi-1HITACHI_730109670008' IQ STORE; Could not execute statement. The file '/dev/disk/by-id/scsi-1HITACHI_730109670008' already exists. -- (st_database.cxx 2215) SQLCODE=-1010000, ODBC 3 State="HY000" Line 1, column 1 For my understanding, the raw device has to exist BEFORE the Db can use it. How can I specify the raw device's name in order to make the command work? Permissions of the device are 770 for the sybase user. Thanks a lot Martin

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• zend_form ViewScript decorator / passing arguments

  - by timpone

  I have a form that is extend from Zend_Form. I am placing the form into a ViewScript decorator like this: $this->setDecorators(array(array('ViewScript', array('viewScript' => 'game/forms/game-management.phtml')))); I'd like to pass in a variable to this ViewScript but am not sure how this could be done. Since the partial renders out as a Zend_View (allowing $this-app_store_icon for rendering), it seems like there should be a way to pass variables to be rendered. I tried the following but to no avail. $this->setDecorators(array(array('ViewScript', array('viewScript' => 'game/forms/game-management.phtml'),array('app_store_picon'=>$current_app_store_picon)))); Any help on how to get this done would be appreciated. thanks

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• Permission Problem While Installing Module With CPAN

  - by neversaint

  I tried to following module using CPAN, but the message I get is the "I have neither the -x permission ..." . How can I resolve that? cpan[3]> install List::MoreUtils is it OK to try to connect to the Internet? [yes] Fetching with LWP: http://www.perl.org/CPAN/authors/id/V/VP/VPARSEVAL/List-MoreUtils-0.22.tar.gz CPAN: Digest::SHA loaded ok (v5.48) Fetching with LWP: http://www.perl.org/CPAN/authors/id/V/VP/VPARSEVAL/CHECKSUMS Checksum for /home/ewijaya/.cpan/sources/authors/id/V/VP/VPARSEVAL/List-MoreUtils-0.22.tar.gz ok Scanning cache /home/neversaint/.cpan/build for sizes .....I have neither the -x permission nor the permission to change the permission; cannot estimate disk usage of '/home/neversaint/.cpan/build/Module-Build-0.3607-Kvb1Vq' .I have neither the -x permission nor the permission to change the permission; cannot estimate disk usage of '/home/neversaint/.cpan/build/ExtUtils-ParseXS-2.2205-zuX4x2' ^CCaught SIGINT, trying to continue

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• Does binarywriter.flush() also flush the underlying filestream object?

  - by jacob sebastian

  I have got a code snippet as follows: Dim fstream = new filestream(some file here) dim bwriter = new binarywriter(fstream) while not end of file read from source file bwriter.write() bwriter.flush() end while The question I have is the following. When I call bwriter.flush() does it also flush the fstream object? Or should I have to explicitly call fstream.flush() such as given in the following example: while not end of file read from source file bwriter.write() bwriter.flush() fstream.flush() end while A few people suggested that I need to call fstream.flush() explicitly to make sure that the data is written to the disk (or the device). However, my testing shows that the data is written to the disk as soon as I call flush() method on the bwriter object. Can some one confirm this?

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• Lock Free Queue -- Single Producer, Multiple Consumers

  - by Shirish

  Hello, I am looking for a method to implement lock-free queue data structure that supports single producer, and multiple consumers. I have looked at the classic method by Maged Michael and Michael Scott (1996) but their version uses linked lists. I would like an implementation that makes use of bounded circular buffer. Something that uses atomic variables? On a side note, I am not sure why these classic methods are designed for linked lists that require a lot of dynamic memory management. In a multi-threaded program, all memory management routines are serialized. Aren't we defeating the benefits of lock-free methods by using them in conjunction with dynamic data structures? I am trying to code this in C/C++ using pthread library on a Intel 64-bit architecture. Thank you, Shirish

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• Slow insert speed in Postgresql memory tablespace

  - by Prashant

  Hi, I have a requirement where I need to store the records at rate of 10,000 records/sec into a database (with indexing on a few fields). Number of columns in one record is 25. I am doing a batch insert of 100,000 records in one transaction block. To improve the insertion rate, I changed the tablespace from disk to RAM.With that I am able to achieve only 5,000 inserts per second. I have also done the following tuning in the postgres config: Indexes : no fsync : false logging : disabled Other information: - Tablespace : RAM - Number of columns in one row : 25 (mostly integers) - CPU : 4 core, 2.5 GHz - RAM : 48 GB I am wondering why a single insert query is taking around 0.2 msec on average when database is not writing anything on disk (as I am using RAM based tablespace). Is there something I am doing wrong? Help appreciated. Prashant

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• How do I design the file storage issue?

  - by user102533

  I am working on an application that creates video files and stores them in a folder in the C:\ drive. I speculate that there will be a large number of these files in the future and we would run out of disk space at some point of time (on our VPS). When the time comes that we have to upgrade, we either plan to use one of the Cloud providers to store files or our existing provider can add another disk (say D:\ drive). Either way, I would want to design the app now in a way that in future, moving to different locations would not be an issue and would be transparent to the end user. The code that creates these files supports 2 ways: myObj.SetOutputToDisk(<path to store>); or myObj.SetOutputToMemoryStream(ms); If we go with the Cloud architecture, I assume we might have the following combination: Cloud Files + Existing VPS or Cloud Files + Cloud Windows Server Given the unknowns at this time, how would I go about designing this?

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• MVC Pattern Clarification

  - by Amutha

  Just I started learning MVC pattern,ofcourse i am learning it from Microsoft's website.Just i want to gather quiz information from the experts. My understanding is (correct me then and there) 1 ) MVC does not support server side events ,but supports client side events.if it supports client side events,i need html page with jQuery/Javascript (view),but most of the example i absorbed is to display the information(model) in view ,i did not see any client side event handling happens in view. 2) Except ViewState and controlState,MVC supports Sessions,Application State management,Cache management. 3) When request goes to MVC engine ,the routing module routes the request that is picked up by the controller.The controller in executes the appropriate action and return the appropriate view.

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• Is it normal for a programmer with 2 years experience to take a long time to code simple programs?

  - by ajax81

  Hi all, I'm a relatively new programmer (18 months on the scene), and I'm finally getting to the point where I'm comfortable accepting projects and developing solutions under minimal supervision. Unfortunately, this also means that I've become acutely aware of my performance shortfalls, the most prevalent of which is the amount of time it takes me to develop, test, and submit algorithms for review. A great example of what I'm talking about occurred this week when I was tasked with developing a simple XML web service (asp.net 3.5) callable via client-side JavaScript, that accepts a single parameter and returns a dataset output to a modal window (please note this is the first time I've had to develop a web service and have had ZERO experience creating/consuming them...let alone calling them from JS client side). Keeping a long story short -- I worked on it for 4 days straight, all day each day, for a grand total of 36 hours, not including the time I spent dwelling on the problem in the shower, the morning commute, and laying awake in bed at night. I learned a great deal about web services and xml/json/javascript...but was called in for a management review to discuss the length of time it took me to develop the solution. In the meeting, I was praised for the quality of my work and was in fact told that my effort was commendable. However, they (senior leads and pm's) weren't impressed with the amount of time it took me to develop the solution and expressed that they would have liked to see the solution in roughly 1/3 of the time it took me. I guess what concerns me the most is that I've identified this pattern as common for myself. Between online videos, book research, and trial/error coding...if its something I haven't seen before, I can spend up to two weeks on a problem that seems to only take the pros in the videos moments to code up. And of course, knowing that management isn't happy with this pattern has shaken me up a bit. To sum up, I have some very specific questions I'd like to ask, and would greatly appreciate your objective professional feedback. Is my experience as a junior programmer common among new developers? Or is it possible that I'm just not cut out for the work? If you suspect that my experience is not common and that there may be an aptitude issue, do you have any suggestions/solutions that I could propose to management to help bring me up to speed? Do seasoned, professional programmers ever encounter knowledge barriers that considerably delay deliverables? When you started out in the industry, did you know how to "do it all"? If not, how long did it take you to be perceived as "proficient"? Was it a natural progression of trial and error, or was there a particular zen moment when you knew you had achieved super saiyen power level? Anyways, thanks for taking the time to read my question(s). I don't know if this is the right place to ask for professional career guidance, but I greatly appreciate your willingness to help me out. Cheers, Daniel

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• ESX3.5 Cluster & MD3000i -- Both servers see iSCSI Targets, Only one server can use partition.

  - by GruffTech

  Alright. First and foremost, Warning. This is a bigger-then-normal question. I like to be thorough and try to eliminate all possible "easymode" answers, as well as give everyone a feel of what i've tried. I've included several images of our setup and the problem it is having.. TLDR Version: So I've followed the guides located here: ESX Deployment Guide V1 this is the guide Dell has sent me to setup two ESX3.5 servers mounting a Dell MD3000i. It doesn't work. Both servers can't use the same storage partition on the MD3000. Both servers see it, but only one server can actually use it. (that server being whatever server created the partition on the target.) Both ESX servers are members of the Host Group. Full Version I have 2 ESX3.5 Servers (10.0.7.102, also called EPI2, and 10.0.7.103, also called EPI3.) connected to a iSCSI SAN Device (Dell MD3000i). Both ESX servers can "scan" the SAN and see the LUNS. Part One: MD3000i Storage On the MD3000i, Both servers are in my host group. I have two partitions, VM1 and VM2, both 1.6TB (vmware doesn't like anything past 2tb.) And you can even see that the ESX servers are targetting the MD3000 just fine. Part Two: The ESX Servers Figure 1. So as you can see above, Both ESX Servers (10.0.7.102 and 10.0.7.103) are able to see and scan the MD3000i SAN. Figure 2. Above is the storage both servers see. I created the storage partition on EPI2 (102). I then Extended the partition to include the second LUN for a grand total of 3.27 TB of storage. When i "rescan" on 103 (the server not mounting the partition), I get the below log in log/messages. Mar 11 10:41:18 epi3 kernel: scsi1: remove-single-device 0 0 0 failed, device busy(4). being the only line that grabs my attentions. (EPI3 is the server name) Mar 11 10:41:04 epi3 vmkiscsid[5436]: Connected to Discovery Address 192.168.130.101 Mar 11 10:41:04 epi3 vmkiscsid[5437]: Connected to Discovery Address 192.168.130.102 Mar 11 10:41:04 epi3 vmkiscsid[5438]: Connected to Discovery Address 192.168.131.101 Mar 11 10:41:04 epi3 vmkiscsid[5439]: Connected to Discovery Address 192.168.131.102 Mar 11 10:41:17 epi3 kernel: scsi singledevice 2 0 0 0 Mar 11 10:41:17 epi3 kernel: Vendor: DELL Model: MD3000i Rev: 0735 Mar 11 10:41:17 epi3 kernel: Type: Direct-Access ANSI SCSI revision: 05 Mar 11 10:41:17 epi3 kernel: VMWARE SCSI Id: Supported VPD pages for sdb : 0x0 0x80 0x83 0x85 0x86 0x87 0xc0 0xc1 0xc2 0xc3 0xc4 0xc8 0xc9 0xca 0xd0 Mar 11 10:41:17 epi3 kernel: VMWARE SCSI Id: Device id info for sdb: 0x1 0x3 0x0 0x10 0x60 0x1 0xe4 0xf0 0x0 0x1a 0x1a 0xa2 0x0 0x0 0x15 0xe2 0x4d 0x75 0xf6 0x99 0x53 0x98 0x0 0x54 0x69 0x71 0x6e 0x2e 0x31 0x39 0x38 0x34 0x2d 0x30 0x35 0x2e 0x63 0x6f 0x6d 0x2e 0x64 0x65 0x6c 0x6c 0x3a 0x70 0x6f 0x77 0x65 0x72 0x76 0x61 0x75 0x6c 0x74 0x2e 0x36 0x30 0x30 0x31 0x65 0x34 0x66 0x30 0x30 0x30 0x31 0x61 0x31 0x61 0x61 0x32 0x30 0x30 0x30 0x30 0x30 0x30 0x30 0x30 0x34 0x37 0x39 0x30 0x36 0x32 0x32 0x65 0x2c 0x74 0x2c 0x30 0x78 0x30 0x30 0x30 0x31 0x30 0x30 0x30 0x30 0x30 0x30 0x30 0x32 0x0 0x0 0x0 0x51 0x94 0x0 0x4 0x0 0x0 0x80 0x1 0x53 0xa8 0x0 0x44 0x69 0x71 0x6e 0x2e 0x31 0x39 0x38 0x34 0x2d 0x30 0x35 0x2e 0x63 0x6f 0x6d 0x2e 0x64 0x65 0x6c 0x6c 0x3a 0x70 0x6f 0x77 0x65 0x72 0x76 0x61 0x75 0x6c 0x74 0x2e 0x36 0x30 0x30 0x31 0x65 0x34 0x66 0x30 0x30 0x30 0x31 0x61 0x31 0x61 0x61 0x32 0x30 0x30 0x30 0x30 0x30 0x30 0x30 0x30 0x34 0x37 0x39 0x30 0x36 0x32 0x32 0x65 0x0 0x0 0x0 0x0 Mar 11 10:41:17 epi3 kernel: VMWARE SCSI Id: Id for sdb 0x60 0x01 0xe4 0xf0 0x00 0x1a 0x1a 0xa2 0x00 0x00 0x15 0xe2 0x4d 0x75 0xf6 0x99 0x4d 0x44 0x33 0x30 0x30 0x30 Mar 11 10:41:17 epi3 kernel: VMWARE: Unique Device attached as scsi disk sdb at scsi2, channel 0, id 0, lun 0 Mar 11 10:41:17 epi3 kernel: Attached scsi disk sdb at scsi2, channel 0, id 0, lun 0 Mar 11 10:41:17 epi3 kernel: scan_scsis starting finish Mar 11 10:41:17 epi3 kernel: SCSI device sdb: 3509329920 512-byte hdwr sectors (1797751 MB) Mar 11 10:41:17 epi3 kernel: sdb: sdb1 Mar 11 10:41:17 epi3 kernel: scan_scsis done with finish Mar 11 10:41:17 epi3 kernel: scsi singledevice 2 0 0 1 Mar 11 10:41:17 epi3 kernel: Vendor: DELL Model: MD3000i Rev: 0735 Mar 11 10:41:17 epi3 kernel: Type: Direct-Access ANSI SCSI revision: 05 Mar 11 10:41:18 epi3 kernel: VMWARE SCSI Id: Supported VPD pages for sdc : 0x0 0x80 0x83 0x85 0x86 0x87 0xc0 0xc1 0xc2 0xc3 0xc4 0xc8 0xc9 0xca 0xd0 Mar 11 10:41:18 epi3 kernel: VMWARE SCSI Id: Device id info for sdc: 0x1 0x3 0x0 0x10 0x60 0x1 0xe4 0xf0 0x0 0x1a 0x1a 0x86 0x0 0x0 0xd 0xb7 0x4d 0x75 0xf2 0x77 0x53 0x98 0x0 0x54 0x69 0x71 0x6e 0x2e 0x31 0x39 0x38 0x34 0x2d 0x30 0x35 0x2e 0x63 0x6f 0x6d 0x2e 0x64 0x65 0x6c 0x6c 0x3a 0x70 0x6f 0x77 0x65 0x72 0x76 0x61 0x75 0x6c 0x74 0x2e 0x36 0x30 0x30 0x31 0x65 0x34 0x66 0x30 0x30 0x30 0x31 0x61 0x31 0x61 0x61 0x32 0x30 0x30 0x30 0x30 0x30 0x30 0x30 0x30 0x34 0x37 0x39 0x30 0x36 0x32 0x32 0x65 0x2c 0x74 0x2c 0x30 0x78 0x30 0x30 0x30 0x31 0x30 0x30 0x30 0x30 0x30 0x30 0x30 0x32 0x0 0x0 0x0 0x51 0x94 0x0 0x4 0x0 0x0 0x80 0x1 0x53 0xa8 0x0 0x44 0x69 0x71 0x6e 0x2e 0x31 0x39 0x38 0x34 0x2d 0x30 0x35 0x2e 0x63 0x6f 0x6d 0x2e 0x64 0x65 0x6c 0x6c 0x3a 0x70 0x6f 0x77 0x65 0x72 0x76 0x61 0x75 0x6c 0x74 0x2e 0x36 0x30 0x30 0x31 0x65 0x34 0x66 0x30 0x30 0x30 0x31 0x61 0x31 0x61 0x61 0x32 0x30 0x30 0x30 0x30 0x30 0x30 0x30 0x30 0x34 0x37 0x39 0x30 0x36 0x32 0x32 0x65 0x0 0x0 0x0 0x0 Mar 11 10:41:18 epi3 kernel: VMWARE SCSI Id: Id for sdc 0x60 0x01 0xe4 0xf0 0x00 0x1a 0x1a 0x86 0x00 0x00 0x0d 0xb7 0x4d 0x75 0xf2 0x77 0x4d 0x44 0x33 0x30 0x30 0x30 Mar 11 10:41:18 epi3 kernel: VMWARE: Unique Device attached as scsi disk sdc at scsi2, channel 0, id 0, lun 1 Mar 11 10:41:18 epi3 kernel: Attached scsi disk sdc at scsi2, channel 0, id 0, lun 1 Mar 11 10:41:18 epi3 kernel: scan_scsis starting finish Mar 11 10:41:18 epi3 kernel: SCSI device sdc: 3509329920 512-byte hdwr sectors (1797751 MB) Mar 11 10:41:18 epi3 kernel: sdc: sdc1 Mar 11 10:41:18 epi3 kernel: scan_scsis done with finish Mar 11 10:41:18 epi3 kernel: scsi1: remove-single-device 0 0 0 failed, device busy(4). Mar 11 10:41:18 epi3 kernel: scsi singledevice 1 0 0 0 Things I've Tried: Removing iSCSI targets from only 103, disabling iSCSI, rebooting, enabled iSCSI, re-adding targets, rescan. Same result. Removing partition on 102, Formatted partition on 103 instead. Same result, except flipped. 103 can use storage, 102 can not. Starting Over. Removing all iSCSI Targets on both ESX Boxes, disabling iSCSI, turning off the firewall for iSCSI, rebooting ESX. Then on the MD3000, Removed the Host Group, Removed the Host-to-Virtual Mappings, Restarted the SAN. Followed the Documentation again, same result. Both servers see the storage, but only one server can use it. Disabling and Re-enabling VMware DRS and HA. Same result. Flat-out turning off VMware DRS and HA, and doing the "start over" step to see if maybe that borked it. Same Result. I'm kinda loosing my mind here, Everything i read online says "just partition it and if the ESX boxes can see the targets, it just works".... well crap. Any ideas, any other things to try? Can anyone atleast point me in the right direction? I'm really tired of working from 1am til 4am (our maintenance hours)

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• iPhone - how to store documents consisting of multiple images?

  - by Joe Strout

  My iPhone (actually, iPad) app creates documents that consist of several images, plus a bit of metadata. What's the best practice for storing these sorts of documents on disk? I see two main options: Create a folder for each document, and store my images as separate PNG files within the folder (plus another little file for the metadata). Create a single file which contains all images and metadata. But I'm not sure how to easily do option 2. I think I can convert my images in PNG format to/from NSData, but then what? I'm still a newbie at Cocoa, but I believe I saw something about stuffing mixed data into some NSSomethingOrOther and having this write itself out to disk, and read itself back in later. Does this ring a bell with anyone? And, will it work with large binary blobs of data like my images? Or would you recommend I simply go with option 1?

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• LNK1106 with big binary resource

  - by E Dominique

  I have a rather huge .dat-file (896MB) included as a BIN resource in my project. Now I get a LNK1106 link error ("fatal error LNK1106: invalid file or disk full: cannot seek to 0x382A3920".) I use Visual Studio 2005 under Windows XP, and have tried on a 4GB RAM machine with high Virtual Memory settings and lots of disk space. I have tried a number of different optimization flags, but to no avail. Does anyone have a clue? EDIT: I have narrowed it down to a specific size of the compiled resource. If the .res file is 544078588 bytes (about 518.9MB) or larger, the error occurs. If it is smaller it works just fine. Still no solution, though...

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• Strange Recurrent Excessive I/O Wait

  - by Chris

  I know quite well that I/O wait has been discussed multiple times on this site, but all the other topics seem to cover constant I/O latency, while the I/O problem we need to solve on our server occurs at irregular (short) intervals, but is ever-present with massive spikes of up to 20k ms a-wait and service times of 2 seconds. The disk affected is /dev/sdb (Seagate Barracuda, for details see below). A typical iostat -x output would at times look like this, which is an extreme sample but by no means rare: iostat (Oct 6, 2013) tps rd_sec/s wr_sec/s avgrq-sz avgqu-sz await svctm %util 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 16.00 0.00 156.00 9.75 21.89 288.12 36.00 57.60 5.50 0.00 44.00 8.00 48.79 2194.18 181.82 100.00 2.00 0.00 16.00 8.00 46.49 3397.00 500.00 100.00 4.50 0.00 40.00 8.89 43.73 5581.78 222.22 100.00 14.50 0.00 148.00 10.21 13.76 5909.24 68.97 100.00 1.50 0.00 12.00 8.00 8.57 7150.67 666.67 100.00 0.50 0.00 4.00 8.00 6.31 10168.00 2000.00 100.00 2.00 0.00 16.00 8.00 5.27 11001.00 500.00 100.00 0.50 0.00 4.00 8.00 2.96 17080.00 2000.00 100.00 34.00 0.00 1324.00 9.88 1.32 137.84 4.45 59.60 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 22.00 44.00 204.00 11.27 0.01 0.27 0.27 0.60 Let me provide you with some more information regarding the hardware. It's a Dell 1950 III box with Debian as OS where uname -a reports the following: Linux xx 2.6.32-5-amd64 #1 SMP Fri Feb 15 15:39:52 UTC 2013 x86_64 GNU/Linux The machine is a dedicated server that hosts an online game without any databases or I/O heavy applications running. The core application consumes about 0.8 of the 8 GBytes RAM, and the average CPU load is relatively low. The game itself, however, reacts rather sensitive towards I/O latency and thus our players experience massive ingame lag, which we would like to address as soon as possible. iostat: avg-cpu: %user %nice %system %iowait %steal %idle 1.77 0.01 1.05 1.59 0.00 95.58 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sdb 13.16 25.42 135.12 504701011 2682640656 sda 1.52 0.74 20.63 14644533 409684488 Uptime is: 19:26:26 up 229 days, 17:26, 4 users, load average: 0.36, 0.37, 0.32 Harddisk controller: 01:00.0 RAID bus controller: LSI Logic / Symbios Logic MegaRAID SAS 1078 (rev 04) Harddisks: Array 1, RAID-1, 2x Seagate Cheetah 15K.5 73 GB SAS Array 2, RAID-1, 2x Seagate ST3500620SS Barracuda ES.2 500GB 16MB 7200RPM SAS Partition information from df: Filesystem 1K-blocks Used Available Use% Mounted on /dev/sdb1 480191156 30715200 425083668 7% /home /dev/sda2 7692908 437436 6864692 6% / /dev/sda5 15377820 1398916 13197748 10% /usr /dev/sda6 39159724 19158340 18012140 52% /var Some more data samples generated with iostat -dx sdb 1 (Oct 11, 2013) Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sdb 0.00 15.00 0.00 70.00 0.00 656.00 9.37 4.50 1.83 4.80 33.60 sdb 0.00 0.00 0.00 2.00 0.00 16.00 8.00 12.00 836.00 500.00 100.00 sdb 0.00 0.00 0.00 3.00 0.00 32.00 10.67 9.96 1990.67 333.33 100.00 sdb 0.00 0.00 0.00 4.00 0.00 40.00 10.00 6.96 3075.00 250.00 100.00 sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 4.00 0.00 0.00 100.00 sdb 0.00 0.00 0.00 2.00 0.00 16.00 8.00 2.62 4648.00 500.00 100.00 sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2.00 0.00 0.00 100.00 sdb 0.00 0.00 0.00 1.00 0.00 16.00 16.00 1.69 7024.00 1000.00 100.00 sdb 0.00 74.00 0.00 124.00 0.00 1584.00 12.77 1.09 67.94 6.94 86.00 Characteristic charts generated with rrdtool can be found here: iostat plot 1, 24 min interval: http://imageshack.us/photo/my-images/600/yqm3.png/ iostat plot 2, 120 min interval: http://imageshack.us/photo/my-images/407/griw.png/ As we have a rather large cache of 5.5 GBytes, we thought it might be a good idea to test if the I/O wait spikes would perhaps be caused by cache miss events. Therefore, we did a sync and then this to flush the cache and buffers: echo 3 > /proc/sys/vm/drop_caches and directly afterwards the I/O wait and service times virtually went through the roof, and everything on the machine felt like slow motion. During the next few hours the latency recovered and everything was as before - small to medium lags in short, unpredictable intervals. Now my question is: does anybody have any idea what might cause this annoying behaviour? Is it the first indication of the disk array or the raid controller dying, or something that can be easily mended by rebooting? (At the moment we're very reluctant to do this, however, because we're afraid that the disks might not come back up again.) Any help is greatly appreciated. Thanks in advance, Chris. Edited to add: we do see one or two processes go to 'D' state in top, one of which seems to be kjournald rather frequently. If I'm not mistaken, however, this does not indicate the processes causing the latency, but rather those affected by it - correct me if I'm wrong. Does the information about uninterruptibly sleeping processes help us in any way to address the problem? @Andy Shinn requested smartctl data, here it is: smartctl -a -d megaraid,2 /dev/sdb yields: smartctl 5.40 2010-07-12 r3124 [x86_64-unknown-linux-gnu] (local build) Copyright (C) 2002-10 by Bruce Allen, http://smartmontools.sourceforge.net Device: SEAGATE ST3500620SS Version: MS05 Serial number: Device type: disk Transport protocol: SAS Local Time is: Mon Oct 14 20:37:13 2013 CEST Device supports SMART and is Enabled Temperature Warning Disabled or Not Supported SMART Health Status: OK Current Drive Temperature: 20 C Drive Trip Temperature: 68 C Elements in grown defect list: 0 Vendor (Seagate) cache information Blocks sent to initiator = 1236631092 Blocks received from initiator = 1097862364 Blocks read from cache and sent to initiator = 1383620256 Number of read and write commands whose size <= segment size = 531295338 Number of read and write commands whose size > segment size = 51986460 Vendor (Seagate/Hitachi) factory information number of hours powered up = 36556.93 number of minutes until next internal SMART test = 32 Error counter log: Errors Corrected by Total Correction Gigabytes Total ECC rereads/ errors algorithm processed uncorrected fast | delayed rewrites corrected invocations [10^9 bytes] errors read: 509271032 47 0 509271079 509271079 20981.423 0 write: 0 0 0 0 0 5022.039 0 verify: 1870931090 196 0 1870931286 1870931286 100558.708 0 Non-medium error count: 0 SMART Self-test log Num Test Status segment LifeTime LBA_first_err [SK ASC ASQ] Description number (hours) # 1 Background short Completed 16 36538 - [- - -] # 2 Background short Completed 16 36514 - [- - -] # 3 Background short Completed 16 36490 - [- - -] # 4 Background short Completed 16 36466 - [- - -] # 5 Background short Completed 16 36442 - [- - -] # 6 Background long Completed 16 36420 - [- - -] # 7 Background short Completed 16 36394 - [- - -] # 8 Background short Completed 16 36370 - [- - -] # 9 Background long Completed 16 36364 - [- - -] #10 Background short Completed 16 36361 - [- - -] #11 Background long Completed 16 2 - [- - -] #12 Background short Completed 16 0 - [- - -] Long (extended) Self Test duration: 6798 seconds [113.3 minutes] smartctl -a -d megaraid,3 /dev/sdb yields: smartctl 5.40 2010-07-12 r3124 [x86_64-unknown-linux-gnu] (local build) Copyright (C) 2002-10 by Bruce Allen, http://smartmontools.sourceforge.net Device: SEAGATE ST3500620SS Version: MS05 Serial number: Device type: disk Transport protocol: SAS Local Time is: Mon Oct 14 20:37:26 2013 CEST Device supports SMART and is Enabled Temperature Warning Disabled or Not Supported SMART Health Status: OK Current Drive Temperature: 19 C Drive Trip Temperature: 68 C Elements in grown defect list: 0 Vendor (Seagate) cache information Blocks sent to initiator = 288745640 Blocks received from initiator = 1097848399 Blocks read from cache and sent to initiator = 1304149705 Number of read and write commands whose size <= segment size = 527414694 Number of read and write commands whose size > segment size = 51986460 Vendor (Seagate/Hitachi) factory information number of hours powered up = 36596.83 number of minutes until next internal SMART test = 28 Error counter log: Errors Corrected by Total Correction Gigabytes Total ECC rereads/ errors algorithm processed uncorrected fast | delayed rewrites corrected invocations [10^9 bytes] errors read: 610862490 44 0 610862534 610862534 20470.133 0 write: 0 0 0 0 0 5022.480 0 verify: 2861227413 203 0 2861227616 2861227616 100872.443 0 Non-medium error count: 1 SMART Self-test log Num Test Status segment LifeTime LBA_first_err [SK ASC ASQ] Description number (hours) # 1 Background short Completed 16 36580 - [- - -] # 2 Background short Completed 16 36556 - [- - -] # 3 Background short Completed 16 36532 - [- - -] # 4 Background short Completed 16 36508 - [- - -] # 5 Background short Completed 16 36484 - [- - -] # 6 Background long Completed 16 36462 - [- - -] # 7 Background short Completed 16 36436 - [- - -] # 8 Background short Completed 16 36412 - [- - -] # 9 Background long Completed 16 36404 - [- - -] #10 Background short Completed 16 36401 - [- - -] #11 Background long Completed 16 2 - [- - -] #12 Background short Completed 16 0 - [- - -] Long (extended) Self Test duration: 6798 seconds [113.3 minutes]

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• memcpy segmentation fault on linux but not os x

  - by Andre

  I'm working on implementing a log based file system for a file as a class project. I have a good amount of it working on my 64 bit OS X laptop, but when I try to run the code on the CS department's 32 bit linux machines, I get a seg fault. The API we're given allows writing DISK_SECTOR_SIZE (512) bytes at a time. Our log record consists of the 512 bytes the user wants to write as well as some metadata (which sector he wants to write to, the type of operation, etc). All in all, the size of the "record" object is 528 bytes, which means each log record spans 2 sectors on the disk. The first record writes 0-512 on sector 0, and 0-15 on sector 1. The second record writes 16-512 on sector 1, and 0-31 on sector 2. The third record writes 32-512 on sector 2, and 0-47 on sector 3. ETC. So what I do is read the two sectors I'll be modifying into 2 freshly allocated buffers, copy starting at record into buf1+the calculated offset for 512-offset bytes. This works correctly on both machines. However, the second memcpy fails. Specifically, "record+DISK_SECTOR_SIZE-offset" in the below code segfaults, but only on the linux machine. Running some random tests, it gets more curious. The linux machine reports sizeof(Record) to be 528. Therefore, if I tried to memcpy from record+500 into buf for 1 byte, it shouldn't have a problem. In fact, the biggest offset I can get from record is 254. That is, memcpy(buf1, record+254, 1) works, but memcpy(buf1, record+255, 1) segfaults. Does anyone know what I'm missing? Record *record = malloc(sizeof(Record)); record->tid = tid; record->opType = OP_WRITE; record->opArg = sector; int i; for (i = 0; i < DISK_SECTOR_SIZE; i++) { record->data[i] = buf[i]; // *buf is passed into this function } char* buf1 = malloc(DISK_SECTOR_SIZE); char* buf2 = malloc(DISK_SECTOR_SIZE); d_read(ad->disk, ad->curLogSector, buf1); d_read(ad->disk, ad->curLogSector+1, buf2); memcpy(buf1+offset, record, DISK_SECTOR_SIZE-offset); memcpy(buf2, record+DISK_SECTOR_SIZE-offset, offset+sizeof(Record)-sizeof(record->data));

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• global scope of variable

  - by shantanuo

  The following shell scrip will check the disk space and change the variable "diskfull" to 1 if the usage is more than 10% The last echo always shows 0 I tried the global diskfull=1 in the if clause but it did not work. How do I change the variable to 1 if the disk consumed is more than 10% #!/bin/sh diskfull=0 ALERT=10 df -HP | grep -vE '^Filesystem|tmpfs|cdrom' | awk '{ print $5 " " $1 }' | while read output; do #echo $output usep=$(echo $output | awk '{ print $1}' | cut -d'%' -f1 ) partition=$(echo $output | awk '{ print $2 }' ) if [ $usep -ge $ALERT ]; then diskfull=1 exit fi done echo $diskfull

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• Any good Open Source or Cheap ASP.NET Catalog Applications

  - by Zhaph - Ben Duguid

  We're looking for a cheap-to-free "off the shelf" ASP.NET catalogue application, that will meet the following requirements: Support two kinds of listings: Suppliers of Services Suppliers of Products, and their Products Suppliers can be categorised by: Area of specialisation - including sub-categories Location Other data, e.g. where listing came from Versioning of supplier/product details Easy to use management interface Use masterpages so we can drop it into our existing site layout Run on a Windows 2003 server, with .NET 3.5 installed In an ideal world, the following additional requirements might be met: Suppliers can manage their own listings Other products that are available to us (that will obviously need some additional development to meet these requirements) are: Content Management System (MS) Commerce Server - bear in mind we're not selling the products/suppliers, just listing them Simple DB application. I'm happy to knock something up in MCMS/simple DB, I'm just looking to see if anyone's had any experience with off the shelf apps that could save us some time. I'm also happy to receive "Don't use this because" type answers. Thanks.

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• A couple questions using fwrite/fread with data structures

  - by Nazgulled

  Hi, I'm using fwrite() and fread() for the first time to write some data structures to disk and I have a couple of questions about best practices and proper ways of doing things. What I'm writing to disk (so I can later read it back) is all user profiles inserted in a Graph structure. Each graph vertex is of the following type: typedef struct sUserProfile { char name[NAME_SZ]; char address[ADDRESS_SZ]; int socialNumber; char password[PASSWORD_SZ]; HashTable *mailbox; short msgCount; } UserProfile; And this is how I'm currently writing all the profiles to disk: void ioWriteNetworkState(SocialNetwork *social) { Vertex *currPtr = social->usersNetwork->vertices; UserProfile *user; FILE *fp = fopen("save/profiles.dat", "w"); if(!fp) { perror("fopen"); exit(EXIT_FAILURE); } fwrite(&(social->usersCount), sizeof(int), 1, fp); while(currPtr) { user = (UserProfile*)currPtr->value; fwrite(&(user->socialNumber), sizeof(int), 1, fp); fwrite(user->name, sizeof(char)*strlen(user->name), 1, fp); fwrite(user->address, sizeof(char)*strlen(user->address), 1, fp); fwrite(user->password, sizeof(char)*strlen(user->password), 1, fp); fwrite(&(user->msgCount), sizeof(short), 1, fp); break; currPtr = currPtr->next; } fclose(fp); } Notes: The first fwrite() you see will write the total user count in the graph so I know how much data I need to read back. The break is there for testing purposes. There's thousands of users and I'm still experimenting with the code. My questions: After reading this I decided to use fwrite() on each element instead of writing the whole structure. I also avoid writing the pointer to to the mailbox as I don't need to save that pointer. So, is this the way to go? Multiple fwrite()'s instead of a global one for the whole structure? Isn't that slower? How do I read back this content? I know I have to use fread() but I don't know the size of the strings, cause I used strlen() to write them. I could write the output of strlen() before writing the string, but is there any better way without extra writes?

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• Error in unzipping a file from a python script running as daemon

  - by Fedrick

  I am getting an error whenever i try to run following unzip command from a python script which is running as a daemon Command : unzip abcd.zip /dev/null Error End-of-central-directory signature not found$ a zip file, or it constitutes one disk of a multi-part archive. In the latter case the central directory and zipfile comment will be found on the last disk(s) of this archive unzip: cannot find zipfile directory in one of abcd.zip$ abcd.zip.zip, and cannot find abcd.zip.ZIP, period. Could anyone help me in this regard? Thanks in advance.

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