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• Server Performance

  - by sb12

  I know very little about performance tuning of servers etc... so i thought i'd put this up here as i start some research on it, just to get some direction. I am in the process of migrating from my old server to a new one - both are 64 bit machines. One is a few years old, the other brand new (PowerEdge R410). The old server spec is: 2 cpus, 3.4GHz Pentiums, 8G of RAM, Fedora 11 currently installed The new server spec is: 16 cpus, 3.2 GHz Xeon, 16G of RAM, CentOS 6.2 installed. Also RAID10 is on the new server - no RAID on the old one. Both servers currently have the same database (MySQL) with the same data migrated. I wrote a Perl script that simply steps through each row of a table in the database (about 18000 rows) and updates a value in that row. Every row in the table is updated. Out of curiosity i ran this perl script on both machines, just to see how the new server would perform vs. the old one, and it produced interesting results: The old server was twice as fast as the new one to complete. Looking at the database, both are configured exactly the same (the new one being a dump of the old one...)... Anyone any ideas why this would be given the hardware gap between both? As i said i'm about to start some digging, but thought i'd put this up here to maybe get some good direction.... Many thanks in advance..

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• Apache ProxyPassReverse and https

  - by joshuaball

  Hi, I would like to map all traffic on 80 and 443 from foo.com to an internal server: 192.168.1.101. I have a VirtualHost (Apache 2.2 on Ubuntu) setup as follows (note, I had to break up the hyperlinks below because I am a 'new user'): <VirtualHost *:80> ServerName foo.com ServerAlias *.foo.com ProxyRequests Off ProxyPreserveHost On <Proxy *> Order deny,allow Allow from all </Proxy> ProxyPass / http://192.168.1.101/ ProxyPassReverse / http://192.168.1.101/ </VirtualHost> And that works great for http traffic. However, I can't seem to do the same thing for https. I have tried: Changing VirtualHost *:80 to * - but that doesn't work (I need it http-http and https-https) Creating a new VirtualHost entry for *:443 that redirects to http://192.168.1.101/, but that fails as well (browser timeouts) I did some searching, here and elsewhere, and the closest question I could find was this, but that didn't quite answer it. Also, just out of curiosity, I tried mapping all ports to https (by changing the two ProxyPass lines from http to https (and removing the :80 from VH), and that didn't work either. How would you do that as well? Any thoughts? Thanks in advance.

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• Difference between accessing a website using Local host and IP address

  - by Cdeez

  I have developed an ASP.NET website and deployed into my IIS server. Now to see that my IIS is installed fine, I type local host in my address bar, and I get the welcome screen of IIS and its documentation in a separate window. Now I gave the url of my website http://localhost/mysites/site2/Default.aspx I access my site. Also giving my IP address instead of local host like: http://192.168.1.46/mysites/site2/Default.aspx also works. Just out of curiosity I wanted to see what happens when I give my IP address in addressbar. It asks me a user name and password saying:The server 192.168.1.46:80 requires a user name and password. I donot know what user name and password it is asking, and as of my knowledge I thought localhost points to my own IP address internally. But what is the difference and also what username and password do I need for it? Update: On chrome and IE just giving localhost displays the welcome screen, but on mozilla, localhost is also asking for a username and password.

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• How do I determine the cause of a sustained spike in mysql queries/activity?

  - by mattmcmanus

  So this is more of a "I'm trying to learn about how this works" question rather than "there is a serious problem I can't figure out!" question. I'm setting up a VPS and have been tweaking and changing things here and there. I recently installed munin (like two days ago) and yesterday I noticed a significant increase in mysql activity. So now my curiosity is going crazy. How do I setup/access mysql's query log? I have about 5 databases on the server so I want to see which one is getting all the action. Is there anything else I can do to keep a better eye on what's going on? Here are the graphs. As you can tell, it's not that much activity at all but I'm just curious at the change. The sites that are on the server right now do not get a lot of traffic. It's running a couple drupal sites, only one of which is live. The live one hasn't had a spike in traffic and the last spike was 250 visitors so it's barely a spike at all.

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• What determines what resolutions a laptop is willing to output over VGA?

  - by Joshua McKinnon

  I'm responsible for several conference rooms and have setup 1080p projectors and I provide both HDMI and VGA connectivity. HDMI for DisplayPort and Mini-DisplayPort, and VGA as a fallback, universal option. Contrary to what I expected, people seem to have much more trouble with the HDMI than VGA, so VGA gets used a lot more than you'd think (even as most workstation laptops made in the last 3-4 years have DisplayPort or Mini-DisplayPort...). Also to my surprise, VGA outputs over 1080p on a 50ft cable run with very minimal degradation on certain laptops - other laptops just don't offer 1080p as a resolution choice and top out at 1600x1200 or something else. Specific example: a ThinkPad W530 will do 1080p, a W520 won't, over VGA. (both do 1080p over displayport/mini-DP) What determines what resolutions a laptop is willing to output over VGA? I'm thinking this will come down to either a video driver that says it supports only certain resolutions for output, or limitations of the RAMDAC (which wouldn't be in play, at least DAC wise, on a digital output, but WOULD on VGA, an analog output). The basic reason for the question is that I noticed, say, a ThinkPad W520 with 1080p built in display, will output 1080p fine over DisplayPort to a 1080p projector, but will cap out at 1600x1200 (practically the same pixel count, just a little shy) on VGA. Now, this wouldn't be surprising at all except SOME laptops have no issue outputting 1080p over VGA, even with lower native resolutions. Why do I care? Well if there's some way I could enable it... for situations where my users end up using VGA anyway, it's preferable for display mirroring if they can output their laptop's native resolution, which, you guessed it, is very often 1080p on 15" models. DISCLAIMER: This is primarily a curiosity, I'm not claiming 1080p over VGA is ideal by any means, but hey, if it works. I've seen HDMI start artifacting more over same-length, same gauge cabling (up to 50' run in certain rooms). If you think this is better suited to SuperUser, please move it, but this is framed from an IT standpoint of something that affects a real pool of users in a multiple conference room, 50+ deployed laptop scenario.

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• Find out the type of an automounted device

  - by Steve Bennett

  I'm working on a system (Ubuntu Precise) with a mount defined in /etc/fstab as follows: /dev/vdb /mnt auto defaults,nobootwait,comment=cloudconfig 0 2 Originally I just wanted to find out if it's NFS (due to potential MySQL locking issues). Judging from man mount, it's not: If no -t option is given, or if the auto type is specified, mount will try to guess the desired type. Mount uses the blkid library for guessing the filesystem type; if that does not turn up anything that looks familiar, mount will try to read the file /etc/filesystems, or, if that does not exist, /proc/filesystems. All of the filesystem types listed there will be tried, except for those that are labeled "nodev" (e.g., devpts, proc and nfs). If /etc/filesystems ends in a line with a single * only, mount will read /proc/filesystems afterwards. But, out of curiosity now, how can I find out more about what type of device it actually is? (For context, this is a VM running on OpenStack. The device is a 60Gb allocation mounted from somewhere - but I don't know how.)` EDIT Including answers here: $ mount /dev/vdb on /mnt type ext3 (rw,_netdev) $ df -T /dev/vdb ext3 61927420 2936068 55845624 5% /mnt

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• How flexible is the 'indirect' function?

  - by Chuck

  My curiosity pushes me to ask this question. If I were to have a series of functions that referenced a different column in a worksheet but all ended on the same row of data is there a way to point the 'row' part of a cell reference to a blank cell and use it has a variable to show the results of the functions up to a desired row simultaneously? Example: =Average('worksheet 1'.$A$1:'worksheet 1'.$A100) =Max('worksheet 1'.$B$1:'worksheet 1'.$B100) =Min('worksheet 1'.$C$1:'worksheet 1'.$C100) =Sum('worksheet 1'.$D$1:'worksheet 1'.$D100) Pseudo formulas... =Average('worksheet 1'.$A$1:'worksheet 1'.$A*('worksheet 2'.$A$1)*) =Max('worksheet 1'.$B$1:'worksheet 1'.$B*('worksheet 2'.$A$1)*) =Min('worksheet 1'.$C$1:'worksheet 1'.$C*('worksheet 2'.$A$1)*) =Sum('worksheet 1'.$D$1:'worksheet 1'.$D*('worksheet 2'.$A$1)*) Where 'worksheet 2'.$A$1 would only contain a number corresponding to a row in 'worksheet 1'. After stumbling upon and playing with the indirect() function I have only been able to replace the entire cell reference (Column and Row) with any success. The formula so far =SUM('worksheet 1'.C3:INDIRECT(A1)) Where A1 is on 'worksheet 2' and contains a full cell reference pointing to 'worksheet 1'. Any pointers?

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• Excluding files from web logs

  - by Ray

  I originally tried this question on StackOverflow, but it was suggested that serverfault was a better choice. So, here it is... Looking through my web logs, I see a lot of entries that don't interest me. Some of them are commonly used images, css files, and scripts, which I can easily exclude by un-checking the 'log visits' check box in IIS for the folder properties. I would also like to exclude log entries for certain common requests which are not in their own folders. Mostly, 'favicon.ico'. 'scriptresource.axd', and 'webresource.axd'. These (especially scriptresource.axd) make up almost a third of a typical log file on my site. So, the question is, how do I tell IIS not to log these requests? And is there any reason that this is a bad idea? The purpose of doing this is to reduce the log file size and the amount of work the server has to do, to make the log file more manageable when I need to dig in to them for troubleshooting, and for my own curiosity. I realize that log file parsers can skip the junk, but I am interested in reducing the raw files, before parsing.

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• Does MySQL log successful or attempted queries?

  - by Nathan Long

  I'm trying to track down a hit-or-miss bug in a web application. Sometimes a request completes just fine; sometimes it hangs and never finishes. I see that Apache now has several requests listed on the server-status page as "sending reply," and that doesn't change. I'm testing on localhost, so there shouldn't ever be more than one. Out of curiosity, I set MySQL to log all queries and I'm tail -fing the log file. When things go OK, I see a pattern like this: 20 Connect root@localhost on dbname 20 Query (some query #1) 20 Query (some query #2) (etc) 20 Quit 21 Connect (etc) When it hangs, I see a pattern like this: 22 Connect root@localhost on dbname 22 Query (some query #1) //nothing happens, so I try the post again 23 Connect root@localhost on dbname 23 Query (some query #1) //nothing happens; try again 24 Connect (etc) Here's my question: is MySQL logging attempted queries, or successful queries? In other words, if the last line I see is query #1, does that imply that query #1 or query #2 is hanging? My guess is that the one I don't see is the problem, because the last one I see looks fine, but maybe the one I don't see is too screwed-up for MySQL to process. Thoughts?

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• Outlook certificate error and separate send/receive error

  - by Richard

  I run a laptop with Vista 32bit and MS Office 2010. Outlook has two profiles, both configured as POP3/SMTP and neither go through an exchange server. Recently, one of the mail servers (hosted with easily) was getting full, so I changed the profile setting to delete from the server if mails are older than 60 days. Suddenly, I am now experiencing a couple of glitches. The first is that I get a certificate error when outlook tries it's first send/receive under the relevant profile - "The server you are connected to is using a security certificate that cannot be verified" This continues despite apparently successfully re-importing the certificate. The second glitch is that I get a "Sending reported error (0x8004010F): 'Outlook data file cannot be accessed'" error on send receive. Strangely, it seems to be trying to send/receive twice - once to 'mail@domain', which works, and the second to 'domain' which doesn't. I've tried deleting the profile and re-creating it, pointing to the original .pst file, but still get both errors. Does anybody know how I can resolve these errors? (As a by note, and not that important, more for curiosity, does anybody know why simply changing the delete from server setting against that profile would cause these issues?)

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• What's the piece of hardware listening on Facebook's or Wikipedia's IP address?

  - by Igor Ostrovsky

  I am trying to understand how massive sites like Facebook or Wikipedia work, for my intellectual curiosity. I read about various techniques for building scalable sites, but I am still puzzled about one particular detail. The part that confuses me is that ultimately, the DNS will map the entire domain to a single IP address, or a handful of IP addresses in the case of round-robin DNS. For example, wikipedia.org has only one type-A DNS record. So, people from all over the world visiting Wikipedia have to send a request to the one IP address specified in DNS. What is the piece of hardware that listens on the IP address for a massive site, and how can it possibly handle all the load coming from the requests for users all over the world? Edit 1: Thanks for all the responses! Anycast seems like a feasible answer... Does anyone know of a way to check whether a particular IP address is anycast-routed, so that I could verify that this really is the trick used in practice by large sites? Edit 2: After more reading on the topic, it appears that anycast is not typically used for dynamic web content. Anycast is usually used for UDP (e.g., DNS lookups), or sometimes for static content. One interesting thing to note is that Facebook uses profile.ak.fbcdn.net to host static content like style sheets and javascript libraries. Each time I ping this name, I get a response from a different IP address. However, I can't tell whether this is anycast in action, or a completely different technique. Back to my original question: as far as I can tell, even a large site will have a single expensive piece of load-balancing hardware listening on its handful of public IP addresses.

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• Will a 2.4Ghz WAP intefere with a 5.0Ghz WAP if placed directly next to each other

  - by Dan

  This is mostly a curiosity question to people who know more about radio and wi-fi than I. The 2.4Ghz band is massively overpopulated near my house to the point of sometimes getting 1000ms pings to the router from only a few feet away. inSSIDer finds at least 10 broadcasting SSID's within around 15 seconds of starting, so this isn't a real surprise to me! Sometimes I can get good results by changing the channel to something like 3 or 8, but it's usually temporary as the others use Auto Channel and hop around. Now, the router I have is capable of 5.0Ghz, as is the laptop I type this on. Switching to 5.0Ghz gives superb results: I can download at ~90Mbps and get consistent 1ms pings. The problem is that only this laptop supports 5.0Ghz! My question: Would I still get decent 5.0Ghz performance if I place a 2.4Ghz access point directly next to my router? And, indeed, will 2.4Ghz continue working as 'normal'? Testing would be an obvious step, but I threw all my superfluous equipment out in a recent house move. My understanding is that I should get good performance, certainly in comparison to having two devices using the same frequency range, but I do believe there will be some impact by the virtue of them being directly next to each other. (Cabling is not an option due to it being a rented house)

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• In an environment with multiple WiFi access points, do wireless clients sometimes connect to both at the same time?

  - by Bobby Burgess

  This is more of a curiosity than a problem, but in this new office I have two D-link DAP-2553's connected in a master/slave array (this just means the master keeps certain configuration options aligned with the slave). The network is set to 802.11n-only, and each AP has the same SSID and WPA2 key. The only difference is that they are on different channels (1 and 11). The WiFi network itself is working well. Users can roam around and the signal/speed is fairly consistent. However, I notice that when I look at the 802.11 client list in the web admin page for each of the 2 APs, I see that certain clients are connected to both, for extended periods of time, but I assume they are only passing data through one of them. Not every client is seen on each AP, but at any given time the same MAC address of a WiFi adapter can be associated (and remain associated) with both APs. The client list auto-refreshes every few seconds so I believe I'm looking at the most recent rather than stale information. One of the WiFi adapters that consistently associates with both APs is an Intel Centrino Wireless-N 1030 (laptop chip). Is it part of the WiFi standard that more than one association per WiFi card can be established concurrently on separate APS?

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• Legalities of freelance security consultant (SQLi) [closed]

  - by Seidr

  Over the years I've gained a large amount of experience in Programming (my main occupation) and server admin, and as a result have a fairly decent backing in security practices. I'm also pretty good at spotting security flaws in software (including but not limited to SQLi), and have built up a list of sites that could definately use some looking at. My question is, what are the legalities of me contacting these sites saying something along the lines of "I've looked at your site and it appears vulnerable - customer data could be compromoised - would you like me to fix it?". Could me finding out that the site is infact vulnerable be construed as an attack itself? If the prospective client so wished, could they take me to court over this? When I find a vulnerable site, all I do is confirm and make a note of the vulnerability. I'm not in it for personal gain (getting paid for FIXING it would be nice!), just curiosity. Is this a viable way to go about finding clients for this kind of work, or would you recommend a more 'legitimate' way? Any suggestions/advice would be greatly appreciated :)

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• Unexpected(?) high 'wasted' memory in memcached

  - by Nanne

  Looking at our memcached stats I think I have found an issue I was not aware of before. It seems that we have a strangely high amount of wasted space. I checked with phpmemcacheadmin for a change, and found this image staring at me: Now I was under the impression that the worst-case scenario would be that there is 50% waste, although I am the first to admit not knowing all the details. I have read - amongst others- this page which is indeed somewhat old, but so is our version of memcached. I think I do understand how the system works (e.g.) I believe, but I have a hard time understanding how we could get to 76% wasted space. The eviction rate that phpmemcacheadmin shows is 2 ev/s, so there is some problem here. The primary question is: what can I do to fix this. I could throw more memory at it (there is some extra available I think), maybe I should fiddle with the slab config (is that even possible with this version?), maybe there are other options? Upgrading the memcached version is not a quickly available option. The secondairy question, out of curiosity, is of course if the rate of 75% (and rising) wasted space is expected, and if so, why. System: This is currently not something I can do anything about, I know the memcached version isn't the newest, but these are the cards I've been dealt. Memcached 1.4.5 Apache 2.2.17 PHP 5.3.5

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• Why does my microwave kill the Wi-Fi?

  - by Ohlin

  Every time I start the microwave in the kitchen, our home Wi-Fi stops working and all devices lose connection with our router! The kitchen and the Wi-Fi router are in opposite ends of the apartment but devices are being used a little here and there. We've been annoyed by the instability of the Wi-Fi for some time and it wasn't until recently we realized it was correlated to microwave usage. After some testing with having the microwave on and off we could narrow down the problem to only occurring when the router is in b/g/n mode and uses a set channel. If I change to b/g mode or set channel to auto then there is no problem any more...but still! The router is a Zyxel P-661HNU ("802.11n Wireless ADSL2+ 4-port Security Gateway" with latest firmware) and the microwave is made by Neff with an effect of 1000W (if this information might be useful to anyone). There is an "internet connection" light on the router and it doesn't go out when the interruption occurs so I think this is only an internal Wi-Fi issue. Now to my questions: What parts of the Wi-Fi can possibly be affected by the microwave usage? Frequency? Disturbances in the electrical system? How can setting Auto on channels make a difference? I thought the different channels were just some kind of separation system within the same frequency spectrum? Could this be a sign that the microwave is malfunctioning and slowly roasting us all at home? Is there any need to be worried? Since we were able to find router settings that cooperate well with our microwave's demand for attention, this question is mainly out of curiosity. But as most people out there...I just can't help the fact that I need to know how it's possible :-)

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• 85 Hz on old/new driver looks the same like 75 Hz on previous one?

  - by jon

  I have old philips 107T5 CRT and Nvidia graphics card. I used old Nvidia driver (but it wasn't 'legacy' one when I installed it) for few years but recently I decided to install other Linux distribution. I used 75 Hz refresh rate and 1024x768 resolution on my previous distribution. After I installed the new distribution I had to install a Nvidia driver so I downloaded one from the Nvidia site (this time only legacy supported my card so I downloaded legacy and installed it). It wasn't automatically updating xorg.conf but I had my previous xorg.conf copy and I used it. When I run X I could only choose 85 and 75 Hz, 85 was checked as default. And now what shocks me: that default 85 Hz looks identically like 75 Hz on previous driver looked (at least to me). I tried 75 Hz out of curiosity and it's too bright, hurts, etc. But on the previous driver 75 Hz wasn't hurting my eyes. Why is it different? It's the same number after all, so it should always give the same results, right? That's my first question. Second question: Is 85 Hz OK for that monitor model? Would it break it? I tried to find the optimal refresh rate for this model but couldn't find it.

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• Intel Motherboard Lightning Victim Dies Hard

  - by Stetson RDT

  Today, I have a more hardware-related question. I have an Intel board, and I really do not know which board it is, I built the machine for a relative, but he forgot to keep the documentation. Long story short, the computer was disconnected during a lightning storm, but a lightning strike travelled in via the ethernet cable (It was directly connected to a power brick commonly seen on those long distance ISP Wireless transmitters), and the motherboard was shocked. I am attempting to get this PC going. The problem is as follows: The computer will randomly reboot, just in the middle of anything as it pleases. May load to EFI (or whatever BIOS is nowadays), may load to bootloader, may even get to the OS. But before 5 minutes is up, the system will always die. Out of curiosity, I plugged my voltmeter in to a molex connector. On the 5V side, it gets a good, consistant +5.13V. On the 12V side, it fluctuates, as follows: Upon immediate startup, it soars to 12.11-12.13V. It will now do one of two things: it will immediately jump down to 12.04-12.05V, or hover for about a minute at 12.11-12.13, then jump down. It seems the longer the voltage stays at 12.11-12.13, the shorter the machine will stay running. Also, post codes, whenever the machine locks up, but does not die hard, seem to be between "AA" and "AC". Does this make any sense to anybody? Do you all think this motherboard is salvageable? It was an expensive bugger, and I'd prefer to not replace it.

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• I (stupidly) converted a TrueCrypt encrypted disk to GPT in Disk Management: now TrueCrypt won't mount it

  - by asilentfire

  Backstory: After moving a Macrium Reflect disk image from my TrueCrypt external drive (with whole disk encryption) onto a unencrypted drive and using Windows PE with Macrium Reflect to restore my internal disk to the recovery image on the external unencrypted drive, my Windows 8 failed to boot. I then went back and also recovered the System Partition (looking now, it is currently EFI), but I still couldn't boot into my backup.. I was in a hurry to get online for something so I just did a clean install of Windows 8, without the backup.. After I installed Windows 8, I went into Disk Management out of curiosity to see if there were other partitions with Windows 8 that Macruim might have missed, and there is (by default) a Recovery Partition of 100MB. My memory of this is hazy, as I was trying to get up and running for an exam at 4 AM: Something in Disk Management prompted me to convert my encrypted external drive to GPT.. I have no idea why I did this, but I went ahead and allowed it to convert my TrueCrypt drive to GPT. Now, I can't mount the drive in TrueCrypt.. Disk Management sees it as Disk 1, Basic, and Unallocated. I tried converting it back to MBR with Disk Management, but no dice with TrueCrypt :( If I try to mount the disk in TrueCrypt I get the message: Incorrect password or not a TrueCrypt volume I should never have messed with a Truecrypt drive in Disk Management, but I did. I have important college work in that drive, and fear I have lost it forever. PLEASE HELP

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• How two completely unrelated software can affect each other in a very strange manner?

  - by user40602

  I installed an old game on my old PC and it doesn't work; its process/exe file was listed in task manager but nothing appeared on the screen. then some time later i discovered that when some specific program was running an my pc, that game could be executed without that problem! although i am myself a power user and also a programmer, i couldn't find the reason, and don't have any good guesses about it. i just know that when i want to run that game i should have another specific and unrelated program running. i ask if anyone has any idea/guess about the possible reasons for this rare phenomenon! oh and if u ask about the details/names of those programs, i am afraid of telling that, because others may think i am kidding, but i am not (please believe me!), that game is NFS2 and the other program is mysqld.exe (i said before that i am a programmer!). I don't know how mysqld.exe (yes it is the windows version of the famous MySQL DBMS server) can affect NFS2 in such an strange manner, and my curiosity and profession don't let me to forget seeking for the answer, so i decided to take the help of others to see if someone has had a similar experience or a reasonable idea about it.

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• How to access a field's value in an object using reflection

  - by kentcdodds

  My Question: How to overcome an IllegalAccessException to access the value of a an object's field using reflection. Expansion: I'm trying to learn about reflection to make some of my projects more generic. I'm running into an IllegalAccessException when trying to call field.getValue(object) to get the value of that field in that object. I can get the name and type just fine. If I change the declaration from private to public then this works fine. But in an effort to follow the "rules" of encapsulation I don't want to do this. Any help would be greatly appreciated! Thanks! My Code: package main; import java.lang.reflect.Field; public class Tester { public static void main(String args[]) throws Exception { new Tester().reflectionTest(); } public void reflectionTest() throws Exception { Person person = new Person("John Doe", "555-123-4567", "Rover"); Field[] fields = person.getClass().getDeclaredFields(); for (Field field : fields) { System.out.println("Field Name: " + field.getName()); System.out.println("Field Type: " + field.getType()); System.out.println("Field Value: " + field.get(person)); //The line above throws: Exception in thread "main" java.lang.IllegalAccessException: Class main.Tester can not access a member of class main.Tester$Person with modifiers "private final" } } public class Person { private final String name; private final String phoneNumber; private final String dogsName; public Person(String name, String phoneNumber, String dogsName) { this.name = name; this.phoneNumber = phoneNumber; this.dogsName = dogsName; } } } The Output: run: Field Name: name Field Type: class java.lang.String Exception in thread "main" java.lang.IllegalAccessException: Class main.Tester can not access a member of class main.Tester$Person with modifiers "private final" at sun.reflect.Reflection.ensureMemberAccess(Reflection.java:95) at java.lang.reflect.AccessibleObject.slowCheckMemberAccess(AccessibleObject.java:261) at java.lang.reflect.AccessibleObject.checkAccess(AccessibleObject.java:253) at java.lang.reflect.Field.doSecurityCheck(Field.java:983) at java.lang.reflect.Field.getFieldAccessor(Field.java:927) at java.lang.reflect.Field.get(Field.java:372) at main.Tester.reflectionTest(Tester.java:17) at main.Tester.main(Tester.java:8) Java Result: 1 BUILD SUCCESSFUL (total time: 0 seconds)

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• Big Data – How to become a Data Scientist and Learn Data Science? – Day 19 of 21

  - by Pinal Dave

  In yesterday’s blog post we learned the importance of the analytics in Big Data Story. In this article we will understand how to become a Data Scientist for Big Data Story. Data Scientist is a new buzz word, everyone seems to be wanting to become Data Scientist. Let us go over a few key topics related to Data Scientist in this blog post. First of all we will understand what is a Data Scientist. In the new world of Big Data, I see pretty much everyone wants to become Data Scientist and there are lots of people I have already met who claims that they are Data Scientist. When I ask what is their role, I have got a wide variety of answers. What is Data Scientist? Data scientists are the experts who understand various aspects of the business and know how to strategies data to achieve the business goals. They should have a solid foundation of various data algorithms, modeling and statistics methodology. What do Data Scientists do? Data scientists understand the data very well. They just go beyond the regular data algorithms and builds interesting trends from available data. They innovate and resurrect the entire new meaning from the existing data. They are artists in disguise of computer analyst. They look at the data traditionally as well as explore various new ways to look at the data. Data Scientists do not wait to build their solutions from existing data. They think creatively, they think before the data has entered into the system. Data Scientists are visionary experts who understands the business needs and plan ahead of the time, this tremendously help to build solutions at rapid speed. Besides being data expert, the major quality of Data Scientists is “curiosity”. They always wonder about what more they can get from their existing data and how to get maximum out of future incoming data. Data Scientists do wonders with the data, which goes beyond the job descriptions of Data Analysist or Business Analysist. Skills Required for Data Scientists Here are few of the skills a Data Scientist must have. Expert level skills with statistical tools like SAS, Excel, R etc. Understanding Mathematical Models Hands-on with Visualization Tools like Tableau, PowerPivots, D3. j’s etc. Analytical skills to understand business needs Communication skills On the technology front any Data Scientists should know underlying technologies like (Hadoop, Cloudera) as well as their entire ecosystem (programming language, analysis and visualization tools etc.) . Remember that for becoming a successful Data Scientist one require have par excellent skills, just having a degree in a relevant education field will not suffice. Final Note Data Scientists is indeed very exciting job profile. As per research there are not enough Data Scientists in the world to handle the current data explosion. In near future Data is going to expand exponentially, and the need of the Data Scientists will increase along with it. It is indeed the job one should focus if you like data and science of statistics. Courtesy: emc Tomorrow In tomorrow’s blog post we will discuss about various Big Data Learning resources. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• Changes in Language Punctuation [closed]

  - by Wes Miller

  More social curiosity than actual programming question... (I got shot for posting this on Stack Overflow. They sent me here. At least i hope here is where they meant.) Based on the few responses I got before the content police ran me off Stack Overflow, I should note that I am legally blind and neatness and consistency in programming are my best friends. A thousand years ago when I took my first programming class (Fortran 66) and a mere 500 years ago when I tokk my first C and C++ classes, there were some pretty standard punctuation practices across languages. I saw them in Basic (shudder), PL/1, PL/AS, Rexx even Pascal. Ok, APL2 is not part of this discussion. Each language has its own peculiar punctuation. Pascal's periods, Fortran's comma separated do loops, almost everybody else's semicolons. As I learned it, each language also has KEYWORDS (if, for, do, while, until, etc.) which are set off by whitespace (or the left margin) if, etc. Each language has function, subroutines of whatever they're called. Some built-in some user coded. They were set off by function_name( parameters );. As in sqrt( x ) or rand( y ); Lately, there seems to be a new set of punctuation rules. Especially in c++ where initializers get glued onto the end of variable declarations int x(0); or auto_ptr p(new gizmo); This usually, briefly fools me into thinking someone is declaring a function prototype or using a function as a integer. Then "if" and 'for' seems to have grown parens; if(true) for(;;), etc. Since when did keywords become functions. I realize some people think they ARE functions with iterators as parameters. But if "for" is a function, where did the arg separating commas go? And finally, functions seem to have shed their parens; sqrt (2) select (...) I know, I koow, loosening whitespace rules is good. Keep reading. Question: when did the old ways disappear and this new way come into vogue? Does anyone besides me find it irritating to read and that the information that the placement of punctuation used to convey is gone? I know full well that K&R put the { at the end of the "if" or "for" to save a byte here and there. Can't use that excuse here. Space as an excuse for loss of readability died as HDD space soared past 100 MiB. Your thoughts are solicited. If there is a good reason to do this, I'll gladly learn it and maybe in another 50 years I'll get used to it. Of course it's good that compilers recognize these (IMHO) typos and keep right on going, but just because you CAN code it that way doesn't mean you HAVE to, right?

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• Tuple - .NET 4.0 new feature

  - by nmarun

  Something I hit while playing with .net 4.0 – Tuple. MSDN says ‘Provides static methods for creating tuple objects.’ and the example below is: 1: var primes = Tuple.Create(2, 3, 5, 7, 11, 13, 17, 19); Honestly, I’m still not sure with what intention MS provided us with this feature, but the moment I saw this, I said to myself – I could use it instead of anonymous types. In order to put this to test, I created an XML file: 1: <Activities> 2: <Activity id="1" name="Learn Tuples" eventDate="4/1/2010" /> 3: <Activity id="2" name="Finish Project" eventDate="4/29/2010" /> 4: <Activity id="3" name="Attend Birthday" eventDate="4/17/2010" /> 5: <Activity id="4" name="Pay bills" eventDate="4/12/2010" /> 6: </Activities> In my console application, I read this file and let’s say I want to pull all the attributes of the node with id value of 1. Now, I have two ways – either define a class/struct that has these three properties and use in the LINQ query or create an anonymous type on the fly. But if we go the .NET 4.0 way, we can do this using Tuples as well. Let’s see the code I’ve written below: 1: var myActivity = (from activity in loaded.Descendants("Activity") 2:       where (int)activity.Attribute("id") == 1 3:       select Tuple.Create( 4: int.Parse(activity.Attribute("id").Value), 5: activity.Attribute("name").Value, 6: DateTime.Parse(activity.Attribute("eventDate").Value))).FirstOrDefault(); Line 3 is where I’m using a Tuple.Create to define my return type. There are three ‘items’ (that’s what the elements are called) in ‘myActivity’ type.. aptly declared as Item1, Item2, Item3. So there you go, you have another way of creating anonymous types. Just out of curiosity, wanted to see what the type actually looked like. So I did a: 1: Console.WriteLine(myActivity.GetType().FullName); and the return was (formatted for better readability): "System.Tuple`3[                            [System.Int32, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089],                            [System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089],                            [System.DateTime, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]                           ]" The `3 specifies the number of items in the tuple. The other interesting thing about the tuple is that it knows the data type of the elements it’s holding. This is shown in the above snippet and also when you hover over myActivity.Item1, it shows the type as an int, Item2 as string and Item3 as DateTime. So you can safely do: 1: int id = myActivity.Item1; 2: string name = myActivity.Item2; 3: DateTime eventDate = myActivity.Item3; Wow.. all I can say is: HAIL 4.0.. HAIL 4.0.. HAIL 4.0

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• Passed: Exam 70-480: Programming in HTML5 with JavaScript and CSS3

  First off: Mission accomplished successfully. And it was fun! Using the resources listed in my previous article about Learning Content, I'd like to thank Microsoft Technical Evangelists Jeremy Foster and Michael Palermo for their excellent jump start videos on Channel 9, and the various authors at Pluralsight. Local Prometric testing centre Back in November I chose a local testing centre which was the easiest to access from my office despite the horrible traffic you might experience here on the island. Actually, it was not the closest one. But due to their website, their awards as Microsoft Learning Center, and my general curiosity about the premises, I gave FRCI my priority. Boy, how should I regret this decision this morning... The official Prometric exam guide asks any attendee to show up at least 30 minutes prior to the scheduled time of the test. Well, this should have been the easier part but unfortunately due to heavier traffic than usual I arrived only 20 minutes before time. Not too bad but more to come. The building called 'le Hub' is nicely renovated and provides the right environment for an IT group of companies like FRCI. I think they have currently 5 independent IT departments over there. Even the handling at the reception was straight forward, welcoming and at my ease. But then... first shock: "We don't have any exam registration for today." - Hm, that's nice... Here's my mail confirmation from Prometric. First attack successfully handled and the lady went off again to check their records. Next shock: A couple of minutes later, another guy tries to explain me that "the staff of the testing centre is already on vacation and the centre is officially closed." - Are you kidding me? Here's the official confirmation by Prometric, and I don't find it funny that I take a day off today only to hear this kind of blubbering nonsense. I thought that I'll be on the safe side choosing a company with a good reputation here on the island. Another 40 (!) minutes later, they finally come back to the waiting area with a pre-filled form about the test appointment. And finally, after an hour of waiting, discussing, restarting the testing PC, and lots of talk, I am allowed to sit down and take the exam. Exam details Well, you know the rules. Signing an NDA doesn't allow me to provide you any details about the questions or topics that have been covered. Please check out the official exam description, and you're on the right way. Sorry, guys... ;-) The result "Congratulations! You have passed this Microsoft Certification exam." - In general, I have to admit that the parts on HTML5 and CSS3 were the easiest after all, and that I have to get myself a little bit more familiar with certain Javascript features like class definitions, inheritance and data security. Anyway, exam passed - who cares about the details? Next goal Of course, the journey to Microsoft Certifications continues and my next goal is to pass exams 70-481 - Essentials of Developing Windows Store Apps using HTML5 and JavaScript and 70-482 - Advanced Windows Store App Development using HTML5 and JavaScript. This would allow me to achieve the certification of MCSD: Windows Store Apps using HTML5. I guess, during 2013 I'll be busy with various learning and teaching lessons.

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