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• Best practices for thin-provisioning Linux servers (on VMware)

  - by nbr

  I have a setup of about 20 Linux machines, each with about 30-150 gigabytes of customer data. Probably the size of data will grow significantly faster on some machines than others. These are virtual machines on a VMware vSphere cluster. The disk images are stored on a SAN system. I'm trying to find a solution that would use disk space sparingly, while still allowing for easy growing of individual machines. In theory, I would just create big disks for each machine and use thin provisioning. Each disk would grow as needed. However, it seems that a 500 GB ext3 filesystem with only 50 GB of data and quite a low number of writes still easily grows the disk image to eg. 250 GB over time. Or maybe I'm doing something wrong here? (I was surprised how little I found on the subject with Google. BTW, there's even no thin-provisioning tag on serverfault.com.) Currently I'm planning to create big, thin-provisioned disks - but with a small LVM volume on them. For example: a 100 GB volume on a 500 GB disk. That way I could more easily grow the LVM volume and the filesystem size as needed, even online. Now for the actual question: Are there better ways to do this? (that is, to grow data size as needed without downtime.) Possible solutions include: Using a thin-provisioning friendly filesystem that tries to occupy the same spots over and over again, thus not growing the image size. Finding an easy method of reclaiming free space on the partition (re-thinning?) Something else? A bonus question: If I go with my current plan, would you recommend creating partitions on the disks (pvcreate /dev/sdX1 vs pvcreate /dev/sdX)? I think it's against conventions to use raw disks without partitions, but it would make it a bit easier to grow the disks, if that is ever needed. This is all just a matter of taste, right?

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• Core Data: Overkill for simple, static UITableView-based iPhone App?

  - by David Foster

  Hello! I have a rather simple iPhone app consisting of numerous views containing a single, grouped table view. These views are held together in navigation controllers which are grouped in a tab bar. Simple stuff. My table views do little more than list text (like "Dog", "Cat" and "Weasel") and this data is being served from a collection of plists. It's perhaps worth mentioning too that these tables are 'static' in the sense that their data is pre-determined and will only ever be amended—and if so, very rarely indeed—by the developer (in this case, moi). This rudimentary approach has reached its limits though, and I think I'm going to need something a bit more relational. I have worked a tad with Core Data in the past, but only with apps whose data is determined by user input. I have four closely related questions: Is Core Data overkill for an app consisting mainly of a selection of simple table views? Do you recommend using Core Data to manage data which is predetermine and extremely unlikely to ever change? Can one lock Core Data down so that its data can't change, thereby relinquishing my responsibility as the developer to handle the editing and saving of the managed object context? How do I go about giving Core Data my predetermined data, and in a format I know that it can work with? Thanks a bunch guys.

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• WRT54GL Tomato Router in Client wireless mode to an iPhone Personal Hotspot

  - by Gordo

  I am trying to connect a router with Tomato firmware to an iPhone 4. The goal is to connect to the Personal Hotspot in Client Wireless mode. This should allow wired and wireless users to connect to the router rather then the iPhone. In theory this should be possible but I am having difficulty. Router Linksys WRT54GL Tomato 1.28.1816 firmware iPhone iPhone 4 iOS 5.1 (9B176) Carrier Rogers Wireless Personal Hotspot works with other devices, wifi/bluetooth/usb iPhone Personal Hotspot settings Mode: B/G Security: WPA or WPA2 Personal Encryption: AES Router IP: 172.20.10.1 Subnet: 172.20.10.0 Min IP: 172.20.10.2 Max IP: 172.20.10.14 maximum number of wireless tethered hosts is 5 I have followed the directions here: http://www.wi-fiplanet.com/tutorials/article.php/3810281 Ensured that the router subnet does not 'collide' with the iPhone subnet. Here is the configuration of the Tomato 'Basic - Network - Wireless' section: http://i.stack.imgur.com/pbmTB.png I have tried several variations of this configuration, but nothing seems to work. NOTE: I have successfully connected to my own wifi network in Wireless Client mode, so I am confident that there are no bad cables or other hardware issues. I would prefer to use Tomato, but DD-WRT maybe my only other option. Thanks!

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• Modeling complex hierarchies

  - by jdn

  To gain some experience, I am trying to make an expert system that can answer queries about the animal kingdom. However, I have run into a problem modeling the domain. I originally considered the animal kingdom hierarchy to be drawn like -animal -bird -carnivore -hawk -herbivore -bluejay -mammals -carnivores -herbivores This I figured would allow me to make queries easily like "give me all birds", but would be much more expensive to say "give me all carnivores", so I rewrote the hierarchy to look like: -animal -carnivore -birds -hawk -mammals -xyz -herbivores -birds -bluejay -mammals But now it will be much slower to query "give me all birds." This is of course a simple example, but it got me thinking that I don't really know how to model complex relationships that are not so strictly hierarchical in nature in the context of writing an expert system to answer queries as stated above. A directed, cyclic graph seems like it could mathematically solve the problem, but storing this in a relational database and maintaining it (updates) would seem like a nightmare to me. I would like to know how people typically model such things. Explanations or pointers to resources to read further would be acceptable and appreciated.

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• PC power supply & normal range for voltages reported in BIOS hardware monitor?

  - by Chris W. Rea

  I'm trying to diagnose whether my computer has an ample power supply. Sometimes when I play a video-intensive game, both monitors lose the video signal, even though the computer remains on and sound playing. A theory I have is: the video card isn't getting sufficient power. I can't imagine it's overheating because the machine is well-ventilated and the video card isn't hot to touch when this happens. Anyway, in my PC's BIOS there's a Hardware Monitor page, and among other voltages reported (such as CPU, DRAM, South Bridge, etc.) I can see the following values: 3.3V 3.152V 5V 4.944V 12V 11.872V Are those the voltages used by peripherals? What voltage should I be referencing if I want to know what my video card (PCI Express) is consuming? What is the normal range of values reported for those? My values above appear to be under by approximately 4.5%, 1.1%, and 1.1% respectively. Is that cause for concern? How else should I be determining if my power supply is "right-sized" for my PC and video card, or am I perhaps barking up the wrong tree?

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• Access 2007 and Special/Unicode Characters in SQL

  - by blockcipher

  I have a small Access 2007 database that I need to be able to import data from an existing spreadsheet and put it into our new relational model. For the most part this seems to work pretty well. Part of the process is attempting to see if a record already exists in a target table using SQL. For example, if I extract book information out of the current row in the spreadsheet, it may contain a title and abstract. I use SQL to get the ID of a matching record, if it exists. This works fine except when I have data that's in a non-English language. In this case, it seems that there is some punctuation that is causing me problems. At least I think it's punctuation as I do have some fields that do not have punctuation and are non-English that do not give me any problems. Is there a built-in function that can escape these characters? Currently I have a small function that will escape the single quote character, but that isn't enough. Or, is there a list of Unicode characters that can interfere with how SQL wants data quoted? Thanks in advance.

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• How ZFS handles online replacement in a RAID-Z (theoretical)

  - by Kevin

  This is a somewhat theoretical question about ZFS and RAID-Z. I'll use a three disk single-parity array as an example for clarity, but the problem can be extended to any number of disks and any parity. Suppose we have disks A, B, and C in the pool, and that it is clean. Suppose now that we physically add disk D with the intention of replacing disk C, and that disk C is still functioning correctly and is only being replaced out of preventive maintenance. Some admins might just yank C and install D, which is a little more organized as devices need not change IDs - however this does leave the array degraded temporarily and so for this example suppose we install D without offlining or removing C. Solaris docs indicate that we can replace a disk without first offlining it, using a command such as: zpool replace pool C D This should cause a resilvering onto D. Let us say that resilvering proceeds "downwards" along a "cursor." (I don't know the actual terminology used in the internal implementation.) Suppose now that midways through the resilvering, disk A fails. In theory, this should be recoverable, as above the cursor B and D contain sufficient parity and below the cursor B and C contain sufficient parity. However, whether or not this is actually recoverable depnds upon internal design decisions in ZFS which I am not aware of (and which the manual doesn't say in certain terms). If ZFS continues to send writes to C below the cursor, then we are fine. If, however, ZFS internally treats C as though it were gone, resilvering D only from parity between A and B and only writing A and B below the cursor, then we're toast. Some experimenting could answer this question but I was hoping maybe someone on here already knows which way ZFS handles this situation. Thank you in advance for any insight!

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• ISBNs are used as primary key, now I want to add non-book things to the DB - should I migrate to EAN

  - by fish2000

  I built an inventory database where ISBN numbers are the primary keys for the items. This worked great for a while as the items were books. Now I want to add non-books. some of the non-books have EANs or ISSNs, some do not. It's in PostgreSQL with django apps for the frontend and JSON api, plus a few supporting python command-line tools for management. the items in question are mostly books and artist prints, some of which are self-published. What is nice about using ISBNs as primary keys is that in on top of relational integrity, you get lots of handy utilities for validating ISBNs, automatically looking up missing or additional information on the book items, etcetera, many of which I've taken advantage. some such tools are off-the-shelf (PyISBN, PyAWS etc) and some are hand-rolled -- I tried to keep all of these parts nice and decoupled, but you know how things can get. I couldn't find anything online about 'private ISBNs' or 'self-assigned ISBNs' but that's the sort of thing I was interested in doing. I doubt that's what I'll settle on, since there is already an apparent run on ISBN numbers. should I retool everything for EAN numbers, or migrate off ISBNs as primary keys in general? if anyone has any experience with working with these systems, I'd love to hear about it, your advice is most welcome.

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• Interruptionless Uploads / Rollback in IIS

  - by NickatUship

  I'm not sure if this is the right way to ask this question, but here's basically what i'd like to do: 1.) Push a changeset to a site in IIS. 2.) Don't interrupt the users. 3.) Be able to roll back effortlessly. So, there are a few things that I know have to happen: 1.) Out of Proc session - handled 2.) Out of Proc cache - handled So the questions that remain: 1.) How do i keep from interrupting the users? If i just upload the files to bin, the app recycles and takes 10+ seconds to come back online 2.) How do i roll back effortlessly? I was thinking a possible solution would be to have two sites set up in IIS, one public and one private. Uploads go to private and get warmed up. After warmup, the sites are swapped. A rollback only entails swapping to private without an upload. This seems sound in theory, but Im not sure of the mechanics. Any ideas?

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• Linq to SQL code generator features

  - by Anders Abel

  I'm very fond of Linq to SQL and the programming model it encourages. I think that in many cases when you are in control of both the database schema and the code it is not worth the effort to have different relational and object models for the data. Working with Linq to SQL makes it simple to have type safe data access from .NET, using the partial extension methods to implement business rules. Unfortunately I do not like the dbml designer due to the lack of a schema refresh function. So far I have used SqlMetal, but that lacks the customization options of the dbml designer. Because of that I've started working on a tool which regenerates the whole code file like SqlMetal, but has the ability to do the customizations that are available in the dbml designer (and maybe more in the future). The customizations will be described in an xml file which only contains those parts that shouldn't have default values. This should keep the xml file size down as well as the maintenance burden of it. To help me focus on the right features, I would like to know: What would be your favourite feature in a linq to sql code generator?

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• Broad Band LAN connection through existing 6 wire phone line ( no phone connected )

  - by Paul Taylor

  I have an (up to but never achieved ) 10 mb broadband signal coming into my house along the telephone line. The modem then connects the broadband signal via a LAN connection and Wi-Fi signal to my computers and iPad. My workshop desk is 54 yards (approx. 50m) downhill from the modem (part of a separate building) – too far to give a good direct signal. The inside corner of the workshop (by a window) receives a weak signal. I have a disconnected telephone cable consisting of 6 wires going from the house to the workshop. The telephone is no longer used in the workshop - we use our mobile number for business calls. A broad band signal using the cable would not have to share with a phone. What would be the most economic price/efficient way to get the broadband signal to the workshop? I am writing in hope that since the telephone didn't need the six wires, an Ethernet connection might be similar and not need all the eight wires for a LAN connection. In theory could use the telephone wire to pull an Ethernet cable trough the underground pipe but I doubt if the cable would survive the strain. The broad band connection in the workshop does not have to have network facility. My skill level is high enough to do house wiring, plumbing and gas fitting; so given any sound advice and a wiring diagram or instructions I can probably work out the rest myself.

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• What arguments to use to explain why a SQL DB is far better then a flat file

  - by jamone

  The higher ups in my company were told by good friends that flat files are the way to go, and we should switch from MS SQL server to them for everything we do. We have over 300 servers and hundreds of different databases. From just the few I'm involved with we have 10 billion records in quite a few of them with upwards of 100k new records a day and who knows how many updates... Me and a couple others need to come up with a response saying why we shouldn't do this. Most of our stuff is ASP.NET with some legacy ASP. We thought that making a simple console app that tests/times the same interactions between a flat file (stored on the network) and SQL over the network doing large inserts, searches, updates etc along with things like network disconnects randomly. This would show them how bad flat files can be espically when you are dealing with millions of records. What things should I use in my response? What should I do with my demo code to illustrate this? My sort list so far: Security Concurent access Performance with large ammounts of data Ammount of time to do such a massive rewrite/switch Lack of transactions PITA to map relational data to flat files I fear that this will be a great post on the Daily WTF someday if I can't stop it now.

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• PHP + MYSQLI: Variable parameter/result binding with prepared statements.

  - by Brian Warshaw

  In a project that I'm about to wrap up, I've written and implemented an object-relational mapping solution for PHP. Before the doubters and dreamers cry out "how on earth?", relax -- I haven't found a way to make late static binding work -- I'm just working around it in the best way that I possibly can. Anyway, I'm not currently using prepared statements for querying, because I couldn't come up with a way to pass a variable number of arguments to the bind_params() or bind_result() methods. Why do I need to support a variable number of arguments, you ask? Because the superclass of my models (think of my solution as a hacked-up PHP ActiveRecord wannabe) is where the querying is defined, and so the find() method, for example, doesn't know how many parameters it would need to bind. Now, I've already thought of building an argument list and passing a string to eval(), but I don't like that solution very much -- I'd rather just implement my own security checks and pass on statements. Does anyone have any suggestions (or success stories) about how to get this done? If you can help me solve this first problem, perhaps we can tackle binding the result set (something I suspect will be more difficult, or at least more resource-intensive if it involves an initial query to determine table structure).

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• Relaying to tech "support" that computer is actually broken.

  - by Sion

  First some background: I have a Dell Inspiron 15R M050, it is still under the Dell limited warranty and the Best Buy Extended warranty. I am currently dual booting Debian Squeeze and Windows 7, the only reason I go into Windows is to play video games specifically steam games. Issue: When I play my games in Windows I am capable of playing for anywhere from 5 minutes to 2 hours before I suffer a hard-lock. I cannot alt-tab, ctrl-alt-delete, ctrl-shift-escape do anything for 2-3 minutes. After this hard-lock period everything runs fine, I can continue the game for probably another hour at least before I suffer another lock. Games: Borderlands, Splinter Cell: Chaos Theory, Starcraft 2, Garrys Mod What I have tried: Running the diagnostic suite in the dell bios, restoring the OEM Windows recovery partition on the HD, fresh installing Windows 7 Professional, updating BIOS, Calling tech support and having them run a software Hardware Diagnostics suite. The question: I think from the research that I have performed that it might be a lack of thermal paste on the CPU, would I be able to go to Best Buy and have them do a hardware diagnostic from the hardware level then have them be able to tell Dell that there is a hardware issue? Or would there be a different problem?

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• How do I prevent my ASP .NET site from continually prompting for user credentials?

  - by gilles27

  I'm trying to get an ASP .NET website up and running on IIS6. The site will run in its own application pool, and uses Windows authentication, with anonymous access turned off. When I run the app pool under NETWORK SERVICE, everything works fine. However we need the app pool to run under a different account, because this account needs some extra privileges (we are printing Word documents). This new account is a member of the local users group, and the IIS_WPG group. It has also been granted the "Log on as a service right". When I browse to the site I am prompted for credentials, not once, but several times. When the page finally loads it looks wrong because the style sheets have not been applied. My suspicion is that I am being prompted once for each file (e.g. all the images, styles and script files) the browser requests, and that for some reason the website is unable to validate those credentials in order to serve the files back. If I allow anonymous access the page loads fine - we don't want to allow it but I mention it in case it offers any further clues. My theory is that perhaps the account the app pool runs under needs permissions to validate domain credentials? If that is so, how do I enable this?

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• Links break in IE9 when using Wordpress plugins in non Wordpress Page

  - by mouli

  I have a site that uses SEF URLs and htaccess RewriteRules to serve up the pages. This has worked fine for several years until the arrival of IE9. Now it appears that the links are not being rewritten and the site is dead in the water. I have tried different compatabilty modes, to no avail, and I've played with the Rewrite Rules over and over, tried different doctypes and a few other browser settings. I agree that it cannot in theory be a browser specific problem if the problem is with the htaccess file but this site works in IE8, firefox and chrome. I have run the rewriterule through a validator and it looks fine. Any ideas would be appreciated as I am running out of ideas. The site is www.marlboroughsounds.co.nz a sample link is http://www.marlboroughsounds.co.nz/walking/freedom-walk-queen-charlotte-track/4dfw and the rewrite rule thats not working looks like this: RewriteRule ^walking/.*/([a-z0-9_]*)/?$ /walking.php?act_code=$1 [L] The link fails and it serves up a browser 404 page, not even the custom 404 I have for the site. Any ideas would be much appreciated as I am stumped.

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• What arguments to use to explain why SQL Server is far better then a flat file

  - by jamone

  The higher ups in my company were told by good friends that flat files are the way to go, and we should switch from SQL Server to them for everything we do. We have over 300 servers and hundreds of different databases. From just the few I'm involved with we have 10 billion records in quite a few of them with upwards of 100k new records a day and who knows how many updates... Me and a couple others need to come up with a response saying why we shouldn't do this. Most of our stuff is ASP.NET with some legacy ASP. We thought that making a simple console app that tests/times the same interactions between a flat file (stored on the network) and SQL over the network doing large inserts, searches, updates etc along with things like network disconnects randomly. This would show them how bad flat files can be especially when you are dealing with millions of records. What things should I use in my response? What should I do with my demo code to illustrate this? My sort list so far: Security Concurrent access Performance with large amounts of data Amount of time to do such a massive rewrite/switch Lack of transactions PITA to map relational data to flat files NTFS doesn't support tons of files in a directory well I fear that this will be a great post on the Daily WTF someday if I can't stop it now.

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• CentOS 6.3 Virtual under OpenVZ cannot ping, host lookups, outbound connections while postfix running

  - by Paul Cravey

  My best theory is that some kernel limit is being hit preventing outbound connections. We have tried basically everything from tcpdumps to provisioning an entirely new virtual server (we do not have this problem on any other virtuals), however the problem somehow carried over, even with new postfix build (working). Emails work, and outbound connections work, so long as postfix does not have too much going on. /proc/user_beancounters shows no limits being hit (show below). Nevertheless, pings fail even to IP addresses. TCP stack appears healthy. Load is low. No iowait. Flushed iptables already. Has anyone experienced anything like this? uid resource held maxheld barrier limit failcnt 3: kmemsize 166216365 170262528 9223372036854775807 9223372036854775807 0 lockedpages 0 0 9223372036854775807 9223372036854775807 0 privvmpages 285727 351885 9223372036854775807 9223372036854775807 0 shmpages 16933 17605 9223372036854775807 9223372036854775807 0 dummy 0 0 0 0 0 numproc 150 303 9223372036854775807 9223372036854775807 0 physpages 314156 326191 0 1280000 0 vmguarpages 0 0 9223372036854775807 9223372036854775807 0 oomguarpages 165355 165355 9223372036854775807 9223372036854775807 0 numtcpsock 89 172 9223372036854775807 9223372036854775807 0 numflock 22 76 9223372036854775807 9223372036854775807 0 numpty 1 2 9223372036854775807 9223372036854775807 0 numsiginfo 0 75 9223372036854775807 9223372036854775807 0 tcpsndbuf 2733472 4371752 9223372036854775807 9223372036854775807 0 tcprcvbuf 1798336 5427296 9223372036854775807 9223372036854775807 0 othersockbuf 491120 1000760 9223372036854775807 9223372036854775807 0 dgramrcvbuf 0 238728 9223372036854775807 9223372036854775807 0 numothersock 361 505 9223372036854775807 9223372036854775807 0 dcachesize 135941831 136114679 9223372036854775807 9223372036854775807 0 numfile 2905 4990 9223372036854775807 9223372036854775807 0 dummy 0 0 0 0 0 dummy 0 0 0 0 0 dummy 0 0 0 0 0 numiptent 8 9 9223372036854775807 9223372036854775807 0 [root@bni /]# ping 4.2.2.1 PING 4.2.2.1 (4.2.2.1) 56(84) bytes of data. --- 4.2.2.1 ping statistics --- 9 packets transmitted, 0 received, 100% packet loss, time 8493ms [root@bni /]# service postfix stop [root@bni /]# ping 4.2.2.1 PING 4.2.2.1 (4.2.2.1) 56(84) bytes of data. 64 bytes from 4.2.2.1: icmp_seq=1 ttl=53 time=8.63 ms 64 bytes from 4.2.2.1: icmp_seq=2 ttl=53 time=8.62 ms 64 bytes from 4.2.2.1: icmp_seq=3 ttl=53 time=8.63 ms 64 bytes from 4.2.2.1: icmp_seq=4 ttl=53 time=8.66 ms Outbound connections of all sorts fail when postfix is running.

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• How to create XSD schema from XML with this kind of structure (in .net)?

  - by Mr. Brownstone

  Here's the problem: my input is XML file that looks something like: <BaseEntityClassInfo> <item> <key>BaseEntityClassInfo.SomeField</key> <value>valueData1</value> </item> <item> <key>BaseEntityClassInfo.AdditionalDataClass.SomeOtherField</key> <value>valueData2</value> </item> <item> <key>BaseEntityClassInfo.AdditionalDataClass.AnotherClassInfo.DisplayedText</key> <value>valueData3</value> </item> ... ... </BaseEntityClassInfo> The <key> element somehow describes entity classes fields and relationships (used in some other app that I don't have access to) and the <value> stores the actual data that I need. My goal is to programatically generate a typed Dataset from this XML that could then be used for creating reports. I thought of building some XSD schema from input XML file first and then use this schema to generate Dataset but I'm not sure how to do that. The problem is that I don't want all data in one table, I need several tables with relationships based on the <key> value so I guess I need to infer relational structure from XML <key> data in some way. So what do you think? How could this be done and what would be the best approach? Any advice, ideas, suggestions would be appreciated!

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• Completed downloads freeze Windows

  - by Ben Hooper

  The Issue Shortly after a file download via Google Chrome for Windows completes, the download will get stuck on "0 seconds left" and all other programs (except Google Chrome, for some reason, but browsing will not work) completely freezes into Windows' infamous "Not Responding" state, affecting Explorer particularly badly. Eventually, the programs will recover themselves but they will recover significantly faster if you cancel the file download, relative to how quickly you react. Performing the exact same operation immediately after cancelling the download usually works without issue. This issue occurs when with any file type (.ZIP, .MSI, .MSG, .PNG, .URL, etc) of any size from any source (Dropbox, SourceForge, Imgur, even tiny and locally-generated BLObs created by my own Chrome extension, etc) to any location.   Potential Causes As this issue is so inconsistent, I haven't been able to prove whether the issue is Chrome-specific or being caused by my system or my Chrome configuration but it's happening on both my work and home PCs. I originally suspected that this issue was being caused by security software scanning completed downloads for threats but I'm not as confident in that theory anymore as the issue persisted even after changing my security software from ESET NOD32 and Malwarebytes Anti-Malware Pro to ESET Endpoint to Microsoft Security Essentials.   System Information (of both PCs) Windows version: 7 Service Pack 1 64-bit Google Chrome version: 30.0.1599.101 (but has been happening for a long time)   Screenshots

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• Bulletin board - Database optimisation

  - by andrew

  This question is a follow on from this Question The project and problem The project I am currently working on is a bulletin board for a large non-profit organisation. The bulletin board will be used to allow inter-office communication within the organisation. I am building the application and have been having trouble extracting the results that I need from my database because I don't think it is properly normalized and because of limitations in my knowledge of relational database theory and mysql. I would appreciate input into the design of the board in general and in particular, ways that the database structure can be improved to facilitate efficient queries and help me develop this application and future application faster Business Logic The bulletin board will be used in the following way Posting bulletins and responses to bulletins Employees or 'users' in offices around the country will be able to post messages to the bulletin board.Bulletins must be posted to a location and categorised- i'll call these "bulletins". Users will be able to post any number of replies to any one bulletin and users will be able to reply to their own bulletin - i'll call these 'replies'. Rating bulletins and replies Users will be able to either 'like' or 'dislike' a bulletin or a reply and the total number of likes or dislikes will be shown for each bulletin or reply. Viewing the bulletin board and responses Bulletins can be displayed chronologically. Users can sort bulletins chronologically or chronologically by the latest reply to that bulletin(let me know if you need more explanation) When a particular bulletin is selected, replies to that bulletin will be displayed chronologically @PerformanceDBA - edited 10:34 est 28/12/10I have begun implementing the data model. I assume that the 6th data model is the physical model because it contains the associative tables. I am going to post any questions that I have below. I will put up a database dump once I am done. I will then put up a list of all the queries that I need to run on the database and begin writing them. I hope you had a good Christmas. I'm in Canada and there's snow! Implementation of Physical model

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• Auto increment with a Unit Of Work

  - by Derick

  Context I'm building a persistence layer to abstract different types of databases that I'll be needing. On the relational part I have mySQL, Oracle and PostgreSQL. Let's take the following simplified MySQL tables: CREATE TABLE Contact ( ID varchar(15), NAME varchar(30) ); CREATE TABLE Address ( ID varchar(15), CONTACT_ID varchar(15), NAME varchar(50) ); I use code to generate system specific alpha numeric unique ID's fitting 15 chars in this case. Thus, if I insert a Contact record with it's Addresses I have my generated Contact.ID and Address.CONTACT_IDs before committing. I've created a Unit of Work (amongst others) as per Martin Fowler's patterns to add transaction support. I'm using a key based Identity Map in the UoW to track the changed records in memory. It works like a charm for the scenario above, all pretty standard stuff so far. The question scenario comes in when I have a database that is not under my control and the ID fields are auto-increment (or in Oracle sequences). In this case I do not have the db generated Contact.ID beforehand, so when I create my Address I do not have a value for Address.CONTACT_ID. The transaction has not been started on the DB session since all is kept in the Identity Map in memory. Question: What is a good approach to address this? (Avoiding unnecessary db round trips) Some ideas: Retrieve the last ID: I can do a call to the database to retrieve the last Id like: SELECT Auto_increment FROM information_schema.tables WHERE table_name='Contact'; But this is MySQL specific and probably something similar can be done for the other databases. If do this then would need to do the 1st insert, get the ID and then update the children (Address.CONTACT_IDs) – all in the current transaction context.

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• Windows Server 08 R2 file share File locking, OSX clients

  - by Keith Loughnane

  I've spent the last two weeks banging my head against this wall. I think I'm starting to understand the problem though. I manage a design company and they have 5 macs (OSX 10.5/.6/.7) connected over SMB to a Windows 2008 R2 file server, another machine functions as Domain Controller (that might not matter). All the macs can connect ok, no issues finding the server or logging in. For the most part things are ok. The problem is files locking up. I thought it was a permissions issue at first but it seems to be file locking. The users open a file; .ind, .pdf etc the file opens, the software reads it and closes it. That's fine, but the folder above the folder locks, it can't be moved and it can't be renamed. Eg: /Working/Project01/Imagefiles/image.pdf /Finished/ The user opens image.pdf, closes it and wants to move the whole Project01 folder into Finished. It gives a username/pass dialogue and then does nothing, no error, or just does nothing. Trying to rename gives a dialogue that says you don't have permission. It looks like it's looking for permission locally, which is why I spent about a week looking at that. Eventually I found that Finder on the macs seems to be keeping the folders open. I can work around it by Killing finder, remounting the shared drive or closing the file through the server manager but this just proves the theory it's not a solution. Has anyone dealt with this problem?

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• ldapsearch against Active Directory fails

  - by Guacamole

  I am using ldapsearch from OpenLDAP tools to search our corporate Active Directory for my email and phone number. This query is a test to ensure that I can authenticate against the domain so I can set up a linux wiki with NTLM authentication. My theory is that if I can successfully query the AD for information, then I am a step closer to getting my wiki to authenticate against AD (I have instructions to set up moin wiki under ActiveDirectory). The problem is that I can't seem to get the ldapsearch query right. I have seen many tutorials on the net that indicate that -D should be something like -D "Americas\John_Marsharll"; however, I keep getting ldap_bind: Invalid credentials (49) error messages when I use Americas\John_Marshall. The only time I get sensical results is when I query with the parameters below. However, even then, I can't figure out how to get email and phone number. [John_Marsharll@WN7-BG3YSM1 ~]$ ldapsearch -x -h 10.1.1.1 \ -b "cn=Users,dc=Americas" mail telephonenumber -D "cn=John_Marshall,dc=Americas" # extended LDIF # # LDAPv3 # base <cn=Users,dc=Americas> with scope subtree # filter: (objectclass=*) # requesting: mail telephonenumber -D cn=John_Marshall,dc=Americas # # search result search: 2 result: 32 No such object # numResponses: 1 [John_Marshall@WN7-BG3YSM1 ~]$ Can someone give me pointers on what I'm doing wrong with the ldapsearch query above? Our AD ldap server is 10.1.1.1 and the AD domain is "Americas".

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• Upstart Script on Centos 6

  - by MarcusMaximus

  I'm trying to create an upstart script to run a python script on startup. In theory it looks simple enough but I just can't seem to get it to work. I'm using a skeleton script I found here and altered. description "Used to start python script as a service" author "Me <[email protected]>" # Stanzas # # Stanzas control when and how a process is started and stopped # See a list of stanzas here: http://upstart.ubuntu.com/wiki/Stanzas#respawn # When to start the service start on runlevel [2345] # When to stop the service stop on runlevel [016] # Automatically restart process if crashed respawn # Essentially lets upstart know the process will detach itself to the background expect fork # Start the process script exec su nonrootuser -c "python /usr/local/scripts/script.py" end script The test script I want it to run is currently a simple python script that runs without any issue when run from a terminal. #!/usr/bin/python2 import os, sys, time if __name__ == "__main__": for i in range (10000): message = "shotgunUpstartTest " , i , time.asctime() , " - Username: " , os.getenv("USERNAME") #print message time.sleep(60) out = open("/var/log/scripts/scriptlogfile", "a") print >> out, message out.close() The location/var/log/scripts has permissions 777 The file /usr/local/scripts/script.py has permissions 775 The upstart script /etc/init.d/pythonupstart.conf has permissions 755

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