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  • Does the Java Memory Model (JSR-133) imply that entering a monitor flushes the CPU data cache(s)?

    - by Durandal
    There is something that bugs me with the Java memory model (if i even understand everything correctly). If there are two threads A and B, there are no guarantees that B will ever see a value written by A, unless both A and B synchronize on the same monitor. For any system architecture that guarantees cache coherency between threads, there is no problem. But if the architecture does not support cache coherency in hardware, this essentially means that whenever a thread enters a monitor, all memory changes made before must be commited to main memory, and the cache must be invalidated. And it needs to be the entire data cache, not just a few lines, since the monitor has no information which variables in memory it guards. But that would surely impact performance of any application that needs to synchronize frequently (especially things like job queues with short running jobs). So can Java work reasonably well on architectures without hardware cache-coherency? If not, why doesn't the memory model make stronger guarantees about visibility? Wouldn't it be more efficient if the language would require information what is guarded by a monitor? As i see it the memory model gives us the worst of both worlds, the absolute need to synchronize, even if cache coherency is guaranteed in hardware, and on the other hand bad performance on incoherent architectures (full cache flushes). So shouldn't it be more strict (require information what is guarded by a monitor) or more lose and restrict potential platforms to cache-coherent architectures? As it is now, it doesn't make too much sense to me. Can somebody clear up why this specific memory model was choosen? EDIT: My use of strict and lose was a bad choice in retrospect. I used "strict" for the case where less guarantees are made and "lose" for the opposite. To avoid confusion, its probably better to speak in terms of stronger or weaker guarantees.

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  • Choosing between Facebook iframe scrollbar or page cut off halfway

    - by pg.
    I have an iframe tab in facebook. I used "overflow:hidden" in the body tag and this code at the bottom of my page: <div id="fb-root"></div> <script type="text/javascript"> window.fbAsyncInit = function() { FB.init({ appId : 'MY_APP_ID', status : true, // check login status cookie : true, // enable cookies to allow the server to access the session xfbml : true // parse XFBML }); FB.Canvas.setAutoResize(100); }; (function() { var e = document.createElement('script'); e.async = true; e.src = document.location.protocol + '//connect.facebook.net/en_US/all.js'; document.getElementById('fb-root').appendChild(e); }()); </script> This removes the scrollbars and resizes the iframe. The problem is that my page is cut off after about 800px (that leaves about 400px). I've set the height in facebook to "fluid". It works absolutely fine in every other browser but not in IE8. As a side question, why does IE still exist? It's the absolute worst thing. Anyways, I added this to the head: <!--[if IE]> <style> body{overflow-y:scroll;} </style> <![endif]--> But that just gets me back to having the scrollbars again.

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  • Using Gem Dependencies if a server is 2.0 instead of 2.1

    - by user548744
    At work for internal Rails applications, the server is running Rails 2.0.4 and Ruby 1.86. As far as I know, that's not going to change anytime soon and I have no control over it. I was going to try and test this out between a couple of computers and was curious if anyone knew what would happen. Being the server is on 2.0.4, I'd like to build Rails 2.3.5 applications for that server if at all possible. From what I understand so far, it won't be a problem if I freeze gems and upack dependancies. Does that sound right? Also, the internal work server has no gems beyond what Rails installs. What I'm wondering is, if I can successfully run a 2.3.5 application on the 2.0.4 server, can I also use extra gems and unpack those to use even though the server doesn't have them? I know that it was version 2.1 that introduced Gem Dependencies so would a 2.3.5 Rails app running on a 2.0.4 server be able to use required gems that are unpacked into an application? One of the worst things with this situation is even if the above stuff works, the server being on 1.86 would exclude me from using a lot of really cool gems that require Ruby 1.87 (like Formtastic). Thanks

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  • Is there a faster method to match an arbitrary String to month name in Java

    - by jonc
    Hello, I want to determine if a string is the name of a month and I want to do it relatively quickly. The function that is currently stuck in my brain is something like: boolean isaMonth( String str ) { String[] months = DateFormatSymbols.getInstance().getMonths(); String[] shortMonths = DateFormatSymbols.getInstance().getShortMonths(); int i; for( i = 0; i<months.length(); ++i;) { if( months[i].equals(str) ) return true; if( shortMonths[i].equals(str ) return true; } return false; } However, I will be processing lots of text, passed one string at a time to this function, and most of the time I will be getting the worst case of going through the entire loop and returning false. I saw another question that talked about a Regex to match a month name and a year which could be adapted for this situation. Would the Regex be faster? Is there any other solution that might be faster?

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  • JavaScript array random index insertion and deletion

    - by Tomi
    I'm inserting some items into array with randomly created indexes, for example like this: var myArray = new Array(); myArray[123] = "foo"; myArray[456] = "bar"; myArray[789] = "baz"; ... In other words array indexes do not start with zero and there will be "numeric gaps" between them. My questions are: Will these numeric gaps be somehow allocated (and therefore take some memory) even when they do not have assigned values? When I delete myArray[456] from upper example, would items below this item be relocated? EDIT: Regarding my question/concern about relocation of items after insertion/deletion - I want to know what happens with the memory and not indexes. More information from wikipedia article: Linked lists have several advantages over dynamic arrays. Insertion of an element at a specific point of a list is a constant-time operation, whereas insertion in a dynamic array at random locations will require moving half of the elements on average, and all the elements in the worst case. While one can "delete" an element from an array in constant time by somehow marking its slot as "vacant", this causes fragmentation that impedes the performance of iteration.

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  • What is the n in O(n) when comparing sorting algorithms?

    - by Mumfi
    The question is rather simple, but I just can't find a good enough answer. I've taken a look at the most upvoted question regarding the Big-Oh notation, namely this: Plain English explanation of Big O It says there that: For example, sorting algorithms are typically compared based on comparison operations (comparing two nodes to determine their relative ordering). Now let's consider the simple bubble sort algorithm: for (int i = arr.length - 1; i > 0 ; i--) { for (int j = 0; j<i; j++) { if (arr[j] > arr[j+1]) { switchPlaces(...) } } } I know that worst case is O(n^2) and best case is O(n), but what is n exactly? If we attempt to sort an already sorted algorithm (best case), we would end up doing nothing, so why is it still O(n)? We are looping through 2 for-loops still, so if anything it should be O(n^2). n can't be the number of comparison operations, because we still compare all the elements, right? This confuses me, and I appreciate if someone could help me.

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  • Misaligned Pointer Performance

    - by Elite Mx
    Aren't misaligned pointers (in the BEST possible case) supposed to slow down performance and in the worst case crash your program (assuming the compiler was nice enough to compile your invalid c program). Well, the following code doesn't seem to have any performance differences between the aligned and misaligned versions. Why is that? /* brutality.c */ #ifdef BRUTALITY xs = (unsigned long *) ((unsigned char *) xs + 1); #endif ... /* main.c */ #include <stdio.h> #include <stdlib.h> #define size_t_max ((size_t)-1) #define max_count(var) (size_t_max / (sizeof var)) int main(int argc, char *argv[]) { unsigned long sum, *xs, *itr, *xs_end; size_t element_count = max_count(*xs) >> 4; xs = malloc(element_count * (sizeof *xs)); if(!xs) exit(1); xs_end = xs + element_count - 1; sum = 0; for(itr = xs; itr < xs_end; itr++) *itr = 0; #include "brutality.c" itr = xs; while(itr < xs_end) sum += *itr++; printf("%lu\n", sum); /* we could free the malloc-ed memory here */ /* but we are almost done */ exit(0); } Compiled and tested on two separate machines using gcc -pedantic -Wall -O0 -std=c99 main.c for i in {0..9}; do time ./a.out; done

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  • How can I avoid garbage collection delays in Java games? (Best Practices)

    - by Brian
    I'm performance tuning interactive games in Java for the Android platform. Once in a while there is a hiccup in drawing and interaction for garbage collection. Usually it's less than one tenth of a second, but sometimes it can be as large as 200ms on very slow devices. I am using the ddms profiler (part of the Android SDK) to search out where my memory allocations come from and excise them from my inner drawing and logic loops. The worst offender had been short loops done like, for(GameObject gob : interactiveObjects) gob.onDraw(canvas); where every single time the loop was executed there was an iterator allocated. I'm using arrays (ArrayList) for my objects now. If I ever want trees or hashes in an inner loop I know that I need to be careful or even reimplement them instead of using the Java Collections framework since I can't afford the extra garbage collection. That may come up when I'm looking at priority queues. I also have trouble where I want to display scores and progress using Canvas.drawText. This is bad, canvas.drawText("Your score is: " + Score.points, x, y, paint); because Strings, char arrays and StringBuffers will be allocated all over to make it work. If you have a few text display items and run the frame 60 times a second that begins to add up and will increase your garbage collection hiccups. I think the best choice here is to keep char[] arrays and decode your int or double manually into it and concatenate strings onto the beginning and end. I'd like to hear if there's something cleaner. I know there must be others out there dealing with this. How do you handle it and what are the pitfalls and best practices you've discovered to run interactively on Java or Android? These gc issues are enough to make me miss manual memory management, but not very much.

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  • Runtime of optimized Primehunter

    - by Setton
    Ok so I need some serious runtime help here! This method should take in an int value, check its primality, and return true if the number is indeed a prime. I understand why the loop only needs to go up to i squared, I understand that the worst case scenario is the case in which either the number is prime (or a multiple of a prime). But I don't understand how to quantify the actual runtime. I have done the loop myself by hand to try to understand the pattern or correlation of the number (n) and how many loops occur, but I literally feel like I keep falling into the same trap every time. I need a new way of thinking about this! I have a hint: "Think about the SIZE of the integer" which makes me want to quantify the literal number of integers in a number in relation to how many iterations it does in the for loop (floor log(n)) +1). BUT IT'S NOT WORKIIIING?! I KNOW it isn't square root n, obviously. I'm asking for Big O notation. public class PrimeHunter { public static boolean isPrime(int n) { boolean answer = (n > 1) ? true : false; //runtime = linear runtime for (int i = 2; i * i <= n; i++) //runtime = ????? { if (n % i == 0) //doesn't occur if it is a prime { answer = false; break; } } return answer; //runtime = linear runtime } }

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  • Unix sort keys cause performance problems

    - by KenFar
    My data: It's a 71 MB file with 1.5 million rows. It has 6 fields All six fields combine to form a unique key - so that's what I need to sort on. Sort statement: sort -t ',' -k1,1 -k2,2 -k3,3 -k4,4 -k5,5 -k6,6 -o output.csv input.csv The problem: If I sort without keys, it takes 30 seconds. If I sort with keys, it takes 660 seconds. I need to sort with keys to keep this generic and useful for other files that have non-key fields as well. The 30 second timing is fine, but the 660 is a killer. More details using unix time: sort input.csv -o output.csv = 28 seconds sort -t ',' -k1 input.csv -o output.csv = 28 seconds sort -t ',' -k1,1 input.csv -o output.csv = 64 seconds sort -t ',' -k1,1 -k2,2 input.csv -o output.csv = 194 seconds sort -t ',' -k1,1 -k2,2 -k3,3 input.csv -o output.csv = 328 seconds sort -t ',' -k1,1 -k2,2 -k3,3 -k4,4 input.csv -o output.csv = 483 seconds sort -t ',' -k1,1 -k2,2 -k3,3 -k4,4 -k5,5 input.csv -o output.csv = 561 seconds sort -t ',' -k1,1 -k2,2 -k3,3 -k4,4 -k5,5 -k6,6 input.csv -o output.csv = 660 seconds I could theoretically move the temp directory to SSD, and/or split the file into 4 parts, sort them separately (in parallel) then merge the results, etc. But I'm hoping for something simpler since looks like sort is just picking a bad algorithm. Any suggestions? Testing Improvements using buffer-size: With 2 keys I got a 5% improvement with 8, 20, 24 MB and best performance of 8% improvement with 16MB, but 6% worse with 128MB With 6 keys I got a 5% improvement with 8, 20, 24 MB and best performance of 9% improvement with 16MB. Testing improvements using dictionary order (just 1 run each): sort -d --buffer-size=8M -t ',' -k1,1 -k2,2 input.csv -o output.csv = 235 seconds (21% worse) sort -d --buffer-size=8M -t ',' -k1,1 -k2,2 input.csv -o ouput.csv = 232 seconds (21% worse) conclusion: it makes sense that this would slow the process down, not useful Testing with different file system on SSD - I can't do this on this server now. Testing with code to consolidate adjacent keys: def consolidate_keys(key_fields, key_types): """ Inputs: - key_fields - a list of numbers in quotes: ['1','2','3'] - key_types - a list of types of the key_fields: ['integer','string','integer'] Outputs: - key_fields - a consolidated list: ['1,2','3'] - key_types - a list of types of the consolidated list: ['string','integer'] """ assert(len(key_fields) == len(key_types)) def get_min(val): vals = val.split(',') assert(len(vals) <= 2) return vals[0] def get_max(val): vals = val.split(',') assert(len(vals) <= 2) return vals[len(vals)-1] i = 0 while True: try: if ( (int(get_max(key_fields[i])) + 1) == int(key_fields[i+1]) and key_types[i] == key_types[i+1]): key_fields[i] = '%s,%s' % (get_min(key_fields[i]), key_fields[i+1]) key_types[i] = key_types[i] key_fields.pop(i+1) key_types.pop(i+1) continue i = i+1 except IndexError: break # last entry return key_fields, key_types While this code is just a work-around that'll only apply to cases in which I've got a contiguous set of keys - it speeds up the code by 95% in my worst case scenario.

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  • OS X: Finder error -36 when using SMB shares on a Samba server bound to AD

    - by Frenchie
    We're looking at deploying SMB homes on Debian (5.0.3) for our mac clients rather than purchasing four new Xserves. We've got our test servers built and functioning properly. Windows clients behave perfectly, but we've run into an issue with OS X (10.6.x and 10.5.x). We're going this route instead of Windows file servers due to a whole bunch of other issues that arise when going that way. Specifically, when mounting a SMB share with unix extensions switched on and the remote server bound to AD, the finder cannot save files on the share, instead touching the file and then bombing out with a -36 IO error, folder creation is fine. Copying files in the terminal behaves fine and the problem seems to be limited to the finder. The issue arises (I think) as the remote UID/GID is passed across when using unix extensions. OS X uses its own winbind idmap (odsam) to work out the effective UID/GID from AD users and groups whilst we're using a rid map on the server. Consequently, there is a mismatch in ownership which the finder chooses to honour. How OS X appears to handle this is to use the remote uid and gid at the file permission level (see below) and then set an OS X acl granting the local uid/gid to have the appropriate permissions on the file. I think the finder touches the file (which the kernel allows because of the ACL) and then checks the filesystem perms and drops out with the IO error. On a Client fc-003353-d:homes2 root# ls -led test/ drwx------+ 2 135978 100513 16384 Feb 3 15:14 test/ 0: user:jfrench allow list,add_file,search,delete,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,writesecurity,chown,file_inherit,directory_inherit 1: group:ARTS\domain users allow 2: group:everyone allow 3: group:owner allow list,add_file,search,delete,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,writesecurity,chown,file_inherit,directory_inherit,only_inherit 4: group:group allow list,add_file,search,delete,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,writesecurity,chown,file_inherit,directory_inherit,only_inherit 5: group:everyone allow list,add_file,search,delete,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,writesecurity,chown,file_inherit,directory_inherit,only_inherit We've tried the following without any luck: Setting the Linux side file owner to match the OS X GID/UID Adding ACLs on the linux filesystem which grant the OS X GID/UID perms Disabling extended attributes Setting steams=no in /etc/nsmb.conf on the client We're currently running a workaround which is to just turn off unix extensions which forces the macs to just mount the share as the local user with u=rwx perms. This works for most things but is causing a few apps that expect certain perms to break in subtle ways. Worst case scenario is that we'll continue running in this way but we would like to have the unix extensions on. Regards. Relevant SMB config below: [global] workgroup = ARTS realm = *snip* security = ADS password server = *snip* unix extensions = yes panic action = /usr/share/panic-action %d idmap backend = rid:ARTS=100000-10000000 idmap uid = 100000-10000000 idmap gid = 100000-10000000 winbind enum users = Yes winbind enum groups = Yes veto files = /lost+found/aquota.*/ hide files = /desktop.ini/$RECYCLE.BIN/.*/AppData/Library/ ea support = yes store dos attributes = yes map system = no map archive = no map readonly = no

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

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

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  • Using smartctl to get vendor specific Attributes from ssd drive behind a SmartArray P410 controller

    - by Lairsdragon
    Hi! Recently I have deployed some HP server with SSD's behind a SmartArray P410 controller. While not official supported from HP the server work well sofar. Now I like to get wear level info's, error statistics etc from the drive. While the SA P410 supports a passthru of the SMART Command to a single drive in the array the output I was not able to the the interesting things from the drive. In this case especially the value the Wear level indicator is from interest for me (Attr.ID 233), but this is ony present if the drive is directly attanched to a SATA Controller. smartctl on directly connected ssd: # smartctl -A /dev/sda smartctl version 5.38 [x86_64-unknown-linux-gnu] Copyright (C) 2002-8 Bruce Allen Home page is http://smartmontools.sourceforge.net/ === START OF READ SMART DATA SECTION === SMART Attributes Data Structure revision number: 5 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 3 Spin_Up_Time 0x0000 100 000 000 Old_age Offline In_the_past 0 4 Start_Stop_Count 0x0000 100 000 000 Old_age Offline In_the_past 0 5 Reallocated_Sector_Ct 0x0002 100 100 000 Old_age Always - 0 9 Power_On_Hours 0x0002 100 100 000 Old_age Always - 8561 12 Power_Cycle_Count 0x0002 100 100 000 Old_age Always - 55 192 Power-Off_Retract_Count 0x0002 100 100 000 Old_age Always - 29 232 Unknown_Attribute 0x0003 100 100 010 Pre-fail Always - 0 233 Unknown_Attribute 0x0002 088 088 000 Old_age Always - 0 225 Load_Cycle_Count 0x0000 198 198 000 Old_age Offline - 508509 226 Load-in_Time 0x0002 255 000 000 Old_age Always In_the_past 0 227 Torq-amp_Count 0x0002 000 000 000 Old_age Always FAILING_NOW 0 228 Power-off_Retract_Count 0x0002 000 000 000 Old_age Always FAILING_NOW 0 smartctl on P410 connected ssd: # ./smartctl -A -d cciss,0 /dev/cciss/c1d0 smartctl 5.39.1 2010-01-28 r3054 [x86_64-unknown-linux-gnu] (local build) Copyright (C) 2002-10 by Bruce Allen, http://smartmontools.sourceforge.net (Right, it is complety empty) smartctl on P410 connected hdd: # ./smartctl -A -d cciss,0 /dev/cciss/c0d0 smartctl 5.39.1 2010-01-28 r3054 [x86_64-unknown-linux-gnu] (local build) Copyright (C) 2002-10 by Bruce Allen, http://smartmontools.sourceforge.net Current Drive Temperature: 27 C Drive Trip Temperature: 68 C Vendor (Seagate) cache information Blocks sent to initiator = 1871654030 Blocks received from initiator = 1360012929 Blocks read from cache and sent to initiator = 2178203797 Number of read and write commands whose size <= segment size = 46052239 Number of read and write commands whose size > segment size = 0 Vendor (Seagate/Hitachi) factory information number of hours powered up = 3363.25 number of minutes until next internal SMART test = 12 Do I hunt here a bug, or is this a limitation of the p410 SMART cmd Passthru?

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  • Windows 7 laptop constantly dropping internet connection

    - by Corbin Holbert
    I have scoured the web for an answer and failed to find one. I am using a Toshiba Satellite laptop running Windows 7 64-Bit. I have the computer connected via Wifi. Now, I am no beginner with the Internet, or anything related to computers, as I have grown up teaching everyone around me how to use computers, and went to college for IT. Everything on my network works flawlessly at all times, except for this evil laptop. The worst part is that I fixed this once before a few years back and recently had to replace the hard drive and re-install the OS, but cannot for the life of me remember what I did to make this problem go away. I am in my browser, connected to the Internet. I click a link. Suddenly no internet access. All I do is click down on the WiFi connection in the task bar, disconnect and reconnect immediately. Internet is back the moment I hit "connect." I have read many people had the same issues as I am having, but they all had triggers or other network issues. I have no trigger (this happens literally five to six times per minute no matter what I am doing) and I have no problems with my router, modem, or any other devices or computers on said network. As I am a web designer, and like to test my work live at every turn- this is going to result in this laptop being in pieces if I can't get it fixed soon. If more info is needed, let me know and I will provide. Thanks for any help offered! EDIT: Network Card: Realtek RTL8188CE Wireless LAN 802.11n PCI-E NIC Network state reads as "No Internet Access" when the problem first occurs, then magically I have Internet access for about ten seconds once I disconnect and reconnect. I have turned off IPV6, I have turned off power saving options for the network adapter, no viruses. Any new ideas? Also, I had to disconnect and reconnect four times just to get to this edit screen- and will likely have to do the same just to post it- it's that bad.

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  • Areca 1280ml RAID6 volume set failed

    - by Richard
    Today we hit some kind of worst case scenario and are open to any kind of good ideas. Here is our problem: We are using several dedicated storage servers to host our virtual machines. Before I continue, here are the specs: Dedicated Server Machine Areca 1280ml RAID controller, Firmware 1.49 12x Samsung 1TB HDDs We configured one RAID6-set with 10 discs that contains one logical volume. We have two hot spares in the system. Today one HDD failed. This happens from time to time, so we replaced it. Upon rebuilding a second disc failed. Normally this is no fun. We stopped heavy IO-operations to ensure a stable RAID rebuild. Sadly the hot-spare disc failed while rebuilding and the whole thing stopped. Now we have the following situation: The controller says that the raid set is rebuilding The controller says that the volume failed It is a RAID 6 system and two discs failed, so the data has to be intact, but we cannot bring the volume online again to access the data. While searching we found the following leads. I don't know whether they are good or bad: Mirroring all the discs to a second set of drives. So we would have the possibility to try different things without loosing more than we already have. Trying to rebuild the array in R-Studio. But we have no real experience with the software. Pulling all drives, rebooting the system, changing into the areca controller bios, reinserting the HDDs one-by-one. Some people are saying that the brought the system online by this. Some are saying that the effect is zero. Some say, that they blew the whole thing. Using undocumented areca commands like "rescue" or "LeVel2ReScUe". Contacting a computer forensics service. But whoa... primary estimates by phone exceeded 20.000€. That's why we would kindly ask for help. Maybe we are missing the obvious? And yes of course, we have backups. But some systems lost one week of data, thats why we'd like to get the system up and running again. Any help, suggestions and questions are more than welcome.

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  • Backing Up vs. Redundancy

    - by TK Kocheran
    I'm currently in stage 2 of 3 of building my home workstation. What this means is that my RAID-0 array of solid state disks will be backed up nightly to a RAID-5 or RAID-6 array of traditional spinning hard disks. However, it recently dawned on me that redundancy is not backup. The main reason for setting up a RAID array with redundancy was to protect myself in the event of a drive failure to serve as an effective backup solution. Wait. What if a bolt of lightning finds a way to travel into my house, through my surge-protector, into my power supply and physically destroys all of my hard disks and SSDs? Well, in that case, I guess I'd be fine because I generally keep most important files (music, pictures, videos) stored in multiple places like on my laptop, my wife's laptop, and an encrypted USB hard drive. Wait. What if a giant hedgehog meteor attacks my house from space traveling at mach 3 and all machines and hard disks are blown to smithereens. Well, I guess I could find a way to do ridiculously slow and cumbersome rsyncs or backups to Amazon's Glacier. Wait. What if there's a nuclear apocalypse... and at this point I start laughing hysterically. At what point does backing up become irrelevant? I completely understand situation one (mechanical drive failure), situation two (workstation compromised or destroyed somehow), possibly even situation three (all machines and disks destroyed), but situation four? There's no questioning the need for backups. None. However, there are three questions I'd really like addressed: To what level should one backup? I definitely understand the merits of physical disk redundancy. I also believe in keeping important files on multiple machines and thinning out the possibility of losing all of my files. Online backups make sense, but they beg the following question. What should I be backing up remotely and how often? It's no problem storage-wise to back up important files (music, pictures, videos) and even configuration and temporal data for all of the machines in my network (all Linux based)... albeit locally. Transferring to the cloud is another story. Worst-case scenario, if I lost all of my configuration for my individual computers, the reality is that I probably lost the machines too. The cloud is a long way away from here; I can run backups over CAT-6 here and see 100MB/s easily, but I'm afraid that I'm only going to see 2MB/s at best when transferring up to the cloud.

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  • Effecient organization of spare cables and hardware

    - by Jake Wharton
    As many of you also likely do, I have a growing collection of cables, hardware, and spare parts (screws, connectors, etc.). I'm looking to find a good system of organization so that everything isn't a tangled mess, mismatched, and potentially able to be damaged. Since the the three things listed above are all have varying sizes and degrees of delicacy this poises an interesting problem. Presently I have those cheap plastic storage bins you find at Wal-mart for everything. Cables that were once wrapped neatly have become tangled due to numerous "I know I have a cable for this" moments. Hardware is mixed in other bins with odds and ends with no protection from each other. NICs, CPUs, and HDDs are all interacting and likely causing damage. Finally there are stray parts sprinkled amongst these two both in plastic bags and loose. I'm looking to unify this storage into a controlled chaos. Here are my thoughts: Odds and ends are the easiest. Screws, connectors, and small electronic parts lend themselves perfectly to tackle boxes and jewelry boxes. Since these are usually dynamically compartmentalized I can adjust for the contents and label them on the outside or inside of the lid. Cables are easily wrangled with short velcro strips but that doesn't stop them from being all mixed in together. Hardware is the worst offender. Size, shape, and degree of delicacy changes with nearly every piece. I'm willing to sacrifice a bit of organization for a somewhat efficient manner. What are all your thoughts? What is the best type of tackle or jewelry box to use? Most of them are cheap and flimsy. Is there a better alternative? How can I organize cables to know exactly (within reason) where one is? What about associating cables with hardware (Wall adapter to router, etc.)? What kind of storage unit lends itself to all shapes of hardware? Do I need to separate by size or degree of delicacy for better organization?

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  • System Requirements of a write-heavy applications serving hundreds of requests per second

    - by Rolando Cruz
    NOTE: I am a self-taught PHP developer who has little to none experience managing web and database servers. I am about to write a web-based attendance system for a very large userbase. I expect around 1000 to 1500 users logged-in at the same time making at least 1 request every 10 seconds or so for a span of 30 minutes a day, 3 times a week. So it's more or less 100 requests per second, or at the very worst 1000 requests in a second (average of 16 concurrent requests? But it could be higher given the short timeframe that users will make these requests. crosses fingers to avoid 100 concurrent requests). I expect two types of transactions, a local (not referring to a local network) and a foreign transaction. local transactions basically download userdata in their locality and cache it for 1 - 2 weeks. Attendance equests will probably be two numeric strings only: userid and eventid. foreign transactions are for attendance of those do not belong in the current locality. This will pass in the following data instead: (numeric) locality_id, (string) full_name. Both requests are done in Ajax so no HTML data included, only JSON. Both type of requests expect at the very least a single numeric response from the server. I think there will be a 50-50 split on the frequency of local and foreign transactions, but there's only a few bytes of difference anyways in the sizes of these transactions. As of this moment the userid may only reach 6 digits and eventid are 4 to 5-digit integers too. I expect my users table to have at least 400k rows, and the event table to have as many as 10k rows, a locality table with at least 1500 rows, and my main attendance table to increase by 400k rows (based on the number of users in the users table) a day for 3 days a week (1.2M rows a week). For me, this sounds big. But is this really that big? Or can this be handled by a single server (not sure about the server specs yet since I'll probably avail of a VPS from ServInt or others)? I tried to read on multiple server setups Heatbeat, DRBD, master-slave setups. But I wonder if they're really necessary. the users table will add around 500 1k rows a week. If this can't be handled by a single server, then if I am to choose a MySQL replication topology, what would be the best setup for this case? Sorry, if I sound vague or the question is too wide. I just don't know what to ask or what do you want to know at this point.

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  • Radeon HD4850 serious issues when using DirectX 10

    - by ricsmania
    Hello, I have a problem with my video card. Whenever I run a DirectX 10 game, it works for a few seconds (10 or so) and then starts displaying nothing but big polygons. I have tested this with Crysis and Resident Evil 5, both have the same problems. The same games running under DirectX 9 work fine, except for some small black squares once in a while. I have the following specs: Asus P7P55D LE Intel Core i5 750 Sapphire Radeon HD4850 1GB 2x2GB Patriot Viper II Sector 5, DDR3 1600 MHz OCZ Stealth X Stream 500SXS 500W At first I thought it could be the video card overheating (it has stock cooling), but the game crashes even when it's running at 50 degrees C, and it's never been higher than 70. I also thought it could be the PSU, but as far as I know 500W is enough for this computer, especially because I haven't overclocked anything. My OS is Windows 7 X64 and I am using Catalyst 10.10, but I have also tried many older versions with no success. I don't think there is a problem with the card itself, or else it wouldn't run DirectX 9 games I believe. I have spent many hours searching for a solution but I couldn't, so any help is appreciated. Thank you. EDIT: I did some further investigation about the problem, and it seems taspeotis was right, it might be related to memory. I slightly underclocked the memory from 993 to 965 MHz and the problem went away completely. Both the black squares using DirectX 9 and the weird polygons using DirectX 10. I was using RE DirectX 10 Benchmark, as it consistently crashed around the same point, and now I can play the full benchmark with no artifacts at all. Unfortunately, the underclock has an obvious hit in performance. Although it's not critical, it's definitely noticeable. So, if the video memory test software showed no erros, but the card needs an underclock to work, what might be the problem? Temperature? Voltage? By the way, I couldn't find what the default voltage for this card is. And what is a good software to try and increase it? I tried Ati Tray Tools but it has a bug that increases the clock speed dramatically whenever I change something in the Overclock tab, so I'm afraid it might fry my card. Worst case scenario, if I don't find I solution I will try to slightly increase the GPU clock to compensate for the memory clock. Thank you again.

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  • Echo 404 directly from nginx to improve performance

    - by user64204
    I am in charge of production servers serving static content for a website. Those servers are constantly being crawled by bots looking for potential exploits (which isn't that much of a problem security-wise because no application can be reached behind the web server) but generates thousands of 404 per day, sometimes per hour. I am looking into ways of blocking those requests but it's tricky (you want to make sure you don't block legitimate traffic and these bots are becoming more and more clever at looking like they're legit) and is going to take me a while to find an acceptable solution. In the meantime I would like to reduce the performance impact of serving those 404 pages. Indeed we're using nginx which by default is configured to serve it's 404 page from the disk (This can be changed using the error_page directive but in the end the 404 will either have to be served from disk or from another external source (e.g. upstream application which would be worst)) which isn't ideal. I ran a test with ab on my local machine with a basic configuration: in one case I echo a message directly from nginx so the disk isn't touched at all, in the other case I hit a missing page and nginx serves its 404 from disk. server { # [...] the default nginx stuff location / { } location /this_page_exists { echo "this page was found"; } } Here are the test results (my laptop has Intel(R) Core(TM) i7-2670QM + SSD in case you're wondering why they are so high): $ ab -n 500000 -c 1000 http://localhost/this_page_exists Requests per second: 25609.16 [#/sec] (mean) $ ab -n 500000 -c 1000 http://localhost/this_page_doesnt_exists Requests per second: 22905.72 [#/sec] (mean) As you can see, returning a value with echo is 11% ((25609-22905)÷22905×100) faster than serving the 404 page from disk. Accordingly I would like to echo a simple 404 Page not Found string from nginx. I tried many things so far but they all failed, essentially the idea was this: location / { try_files $uri @not_found; } location @not_found { echo "404 - Page not found"; } The problem is that as soon as the echo directive is used, the http response code is set to 200. I tried changing that by doing error_page 200 = 400 but that breaks the configuration. How can I serve a 404 page directly from nginx? (without hacking the source which may be might next step)

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  • cd Command Linux and Mystery Flags

    - by Jason R. Mick
    Platform: CentOS 6.2 Shell:tcsh I'm playing around with cd for a BASH script, and noticed the wondrous cd - option, but was left with many questions... Why the cd -? Isn't this redundant with cd ..? EDIT [As FatalError points out, these two commands don't do the same things... so the answer is "no"] Can you delve farther back into your history with - flag, a la in a browser? e.g. When I type cd -, it takes me to my previous directory, but then if I enter that command again, it takes me to the directory I just came from, creating a sort of loop. Is a shorthand for going back multiple levels supported?EDITI realize I can go back with cd .., but was hoping this could be a gateway to a less verbose deep back, e.g. cd -3 vs. cd ../../../ ... hopefully that clarifies what I'm asking....EDIT2As to the current feedback, while .. is a special directory, I don't see a reason why the built-in cd to the terminal couldn't use a shorthand for ../../ ... ../ e.g. cd ..5 or why the built-in also couldn't have a history (a la auto pushd/popd) that could be turned on and used like cd -3. I get that this could be somewhat of security/privacy risk, but I don't see how it's any worst than storing a command history, which most shells/terminals do. The manpage for cd, accessible via man cd and help cd (it's the same for either command), only lists -L and -P flags. However when I type in cd --help it outputs Usage: cd [-plvn][-|<dir>].. Am I right in assuming the other flags and the - (back) option are nonstandard? What are the -n and -v flags for? Both seem to take me back to my home directory, that's all I've been able to figure out via experimentation. A quick read on web resources [1][2] offered just the same sort of info that the man page did and didn't answer my questions. Note: The second Linux-centric resource above claimed cd only had two options (obviously not true in current CentOS) hence my assumption that this functionality could be non-standard.

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  • Why is my concurrency capacity so low for my web app on a LAMP EC2 instance?

    - by AMF
    I come from a web developer background and have been humming along building my PHP app, using the CakePHP framework. The problem arose when I began the ab (Apache Bench) testing on the Amazon EC2 instance in which the app resides. I'm getting pretty horrendous average page load times, even though I'm running a c1.medium instance (2 cores, 2GB RAM), and I think I'm doing everything right. I would run: ab -n 200 -c 20 http://localhost/heavy-but-view-cached-page.php Here are the results: Concurrency Level: 20 Time taken for tests: 48.197 seconds Complete requests: 200 Failed requests: 0 Write errors: 0 Total transferred: 392111200 bytes HTML transferred: 392047600 bytes Requests per second: 4.15 [#/sec] (mean) Time per request: 4819.723 [ms] (mean) Time per request: 240.986 [ms] (mean, across all concurrent requests) Transfer rate: 7944.88 [Kbytes/sec] received While the ab test is running, I run VMStat, which shows that Swap stays at 0, CPU is constantly at 80-100% (although I'm not sure I can trust this on a VM), RAM utilization ramps up to about 1.6G (leaving 400M free). Load goes up to about 8 and site slows to a crawl. Here's what I think I'm doing right on the code side: In Chrome browser uncached pages typically load in 800-1000ms, and cached pages load in 300-500ms. Not stunning, but not terrible either. Thanks to view caching, there might be at most one DB query per page-load to write session data. So we can rule out a DB bottleneck. I have APC on. I am using Memcached to serve the view cache and other site caches. xhprof code profiler shows that cached pages take up 10MB-40MB in memory and 100ms - 1000ms in wall time. Pages that would be the worst offenders would look something like this in xhprof: Total Incl. Wall Time (microsec): 330,143 microsecs Total Incl. CPU (microsecs): 320,019 microsecs Total Incl. MemUse (bytes): 36,786,192 bytes Total Incl. PeakMemUse (bytes): 46,667,008 bytes Number of Function Calls: 5,195 My Apache config: KeepAlive On MaxKeepAliveRequests 100 KeepAliveTimeout 3 <IfModule mpm_prefork_module> StartServers 5 MinSpareServers 5 MaxSpareServers 10 MaxClients 120 MaxRequestsPerChild 1000 </IfModule> Is there something wrong with the server? Some gotcha with the EC2? Or is it my code? Some obvious setting I should look into? Too many DNS lookups? What am I missing? I really want to get to 1,000 concurrency capacity, but at this rate, it ain't gonna happen.

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  • Need help troubleshooting highly variable ping times

    - by Elliot.Bradshaw
    I'm at work using Citrix (think Remote Desktop) to connect to client sites. With my job I have to write a fair bit of code while I'm connected remotely via Citrix, so the latency of my internet connection is important. If I'm getting ping times above 250ms, then it becomes almost impossible to scroll, click or type with accuracy. Recently my Comcast business internet has been exhibiting highly variable ping times. If I ping google.com, I'll get pings that range from 9ms all the way up to 1300ms. The problem seems to be at its worst during the hours of 1PM to 4:30PM. Outside of those hours and the variance in pings settles down, mostly between 9ms and 50ms. The signal to noise ratio and upstream power are both fine on my modem--the values are here: http://pastebin.com/D4hWGPXf I ran a trace route from my computer to google.com (the results of which are here: http://pastebin.com/GcdjYvMh) and did another test ping to the IP of the first hop outside of our local network (73.98.44.1)--the variance in ping times existed in exactly the same manner as if I were pinging Google. Connecting directly to the cable modem by CAT5 makes no difference. Here is a screenshot demonstrating the variance of the ping times: http://postimage.org/image/haocdeauv/full/ -- as you can see it can get pretty bad. Three Comcast techs have been out (two of them were here when the problem wasn't happening) and they as well as the regional tier 2 Comcast support were unable to diagnose the problem. I now have a ticket open with tier 3 support, but have yet to hear back from them. Does anyone know what could cause these sorts of problems or have any idea from the traceroute above where it could be originating? The regional tier 2 guy tried to tell me that what I'm seeing is normal--are highly variable ping times like that ever acceptable? Anything I should ask Comcast to do or look at to get this problem fixed? Any tips/advice much appreciated! Edit: This is Comcast cable internet at a small start-up, we've ruled out congestion in our private LAN as a cause (i.e., no one's watching YouTube when the pings become variable). Update: Tier 3 Comcast support advised swapping out the modem, a tech came here today and did that--same problem persists.

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  • Xml failing to deserialise

    - by Carnotaurus
    I call a method to get my pages [see GetPages(String xmlFullFilePath)]. The FromXElement method is supposed to deserialise the LitePropertyData elements to strongly type LitePropertyData objects. Instead it fails on the following line: return (T)xmlSerializer.Deserialize(memoryStream); and gives the following error: <LitePropertyData xmlns=''> was not expected. What am I doing wrong? I have included the methods that I call and the xml data: public static T FromXElement<T>(this XElement xElement) { using (var memoryStream = new MemoryStream(Encoding.ASCII.GetBytes(xElement.ToString()))) { var xmlSerializer = new XmlSerializer(typeof(T)); return (T)xmlSerializer.Deserialize(memoryStream); } } public static List<LitePageData> GetPages(String xmlFullFilePath) { XDocument document = XDocument.Load(xmlFullFilePath); List<LitePageData> results = (from record in document.Descendants("row") select new LitePageData { Guid = IsValid(record, "Guid") ? record.Element("Guid").Value : null, ParentID = IsValid(record, "ParentID") ? Convert.ToInt32(record.Element("ParentID").Value) : (Int32?)null, Created = Convert.ToDateTime(record.Element("Created").Value), Changed = Convert.ToDateTime(record.Element("Changed").Value), Name = record.Element("Name").Value, ID = Convert.ToInt32(record.Element("ID").Value), LitePageTypeID = IsValid(record, "ParentID") ? Convert.ToInt32(record.Element("ParentID").Value) : (Int32?)null, Html = record.Element("Html").Value, FriendlyName = record.Element("FriendlyName").Value, Properties = record.Element("Properties") != null ? record.Element("Properties").Element("LitePropertyData").FromXElement<List<LitePropertyData>>() : new List<LitePropertyData>() }).ToList(); return results; } Here is the xml: <?xml version="1.0" encoding="utf-8"?> <root> <rows> <row> <ID>1</ID> <ImageUrl></ImageUrl> <Html>Home page</Html> <Created>01-01-2012</Created> <Changed>01-01-2012</Changed> <Name>Home page</Name> <FriendlyName>home-page</FriendlyName> </row> <row xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Guid>edeaf468-f490-4271-bf4d-be145bc6a1fd</Guid> <ID>8</ID> <Name>Unused</Name> <ParentID>1</ParentID> <Created>2006-03-25T10:57:17</Created> <Changed>2012-07-17T12:24:30.0984747+01:00</Changed> <ChangedBy /> <LitePageTypeID xsi:nil="true" /> <Html> What is the purpose of this option? This option checks the current document for accessibility issues. It uses Bobby to provide details of whether the current web page conforms to W3C's WCAG criteria for web content accessibility. Issues with Bobby and Cynthia Bobby and Cynthia are free services that supposedly allow a user to expose web page accessibility barriers. It is something of a guide but perhaps a blunt instrument. I tested a few of the webpages that I have designed. Sure enough, my pages fall short and for good reason. I am not about to claim that Bobby and Cynthia are useless. Although it is useful and commendable tool, it project appears to be overly ambitious. Nevertheless, let me explain my issues with Bobby and Cynthia: First, certain W3C standards for designing web documents are often too strict and unworkable. For instance, in some versions W3C standards for HTML, certain tags should not include a particular attribute, whereas in others they are requisite if the document is to be ???well-formed???. The standard that a designer chooses is determined usually by the requirements specification document. This specifies which browsers and versions of those browsers that the web page is expected to correctly display. Forcing a hypertext document to conform strictly to a specific W3C standard for HTML is often no simple task. In the worst case, it cannot conform without losing some aesthetics or accessibility functionality. Second, the case of HTML documents is not an isolated case. Standards for XML, XSL, JavaScript, VBScript, are analogous. Therefore, you might imagine the problems when you begin to combine these languages and formats in an HTML document. Third, there is always more than one way to skin a cat. For example, Bobby and Cynthia may flag those IMG tags that do not contain a TITLE attribute. There might be good reason that a web developer chooses not to include the title attribute. The title attribute has a limited numbers of characters and does not support carriage returns. This is a major defect in the design of this tag. In fact, before the TITLE attribute was supported, there was the ALT attribute. Most browsers support both, yet they both perform a similar function. However, both attributes share the same deficiencies. In practice, there are instances where neither attribute would be used. Instead, for example, the developer would write some JavaScript or VBScript to circumvent these deficiencies. The concern is that Bobby and Cynthia would not notice this because it does not ???understand??? what the JavaScript does. </Html> <FriendlyName>unused</FriendlyName> <IsDeleted>false</IsDeleted> <Properties> <LitePropertyData> <Description>Image for the page</Description> <DisplayEditUI>true</DisplayEditUI> <OwnerTab>1</OwnerTab> <DisplayName>Image Url</DisplayName> <FieldOrder>1</FieldOrder> <IsRequired>false</IsRequired> <Name>ImageUrl</Name> <IsModified>false</IsModified> <ParentPageID>3</ParentPageID> <Type>String</Type> <Value xsi:type="xsd:string">smarter.jpg</Value> </LitePropertyData> <LitePropertyData> <Description>WebItemApplicationEnum</Description> <DisplayEditUI>true</DisplayEditUI> <OwnerTab>1</OwnerTab> <DisplayName>WebItemApplicationEnum</DisplayName> <FieldOrder>1</FieldOrder> <IsRequired>false</IsRequired> <Name>WebItemApplicationEnum</Name> <IsModified>false</IsModified> <ParentPageID>3</ParentPageID> <Type>Number</Type> <Value xsi:type="xsd:string">1</Value> </LitePropertyData> </Properties> <Seo> <Author>Phil Carney</Author> <Classification /> <Copyright>Carnotaurus</Copyright> <Description> What is the purpose of this option? This option checks the current document for accessibility issues. It uses Bobby to provide details of whether the current web page conforms to W3C's WCAG criteria for web content accessibility. Issues with Bobby and Cynthia Bobby and Cynthia are free services that supposedly allow a user to expose web page accessibility barriers. It is something of a guide but perhaps a blunt instrument. I tested a few of the webpages that I have designed. Sure enough, my pages fall short and for good reason. I am not about to claim that Bobby and Cynthia are useless. Although it is useful and commendable tool, it project appears to be overly ambitious. Nevertheless, let me explain my issues with Bobby and Cynthia: First, certain W3C standards for designing web documents are often too strict and unworkable. For instance, in some versions W3C standards for HTML, certain tags should not include a particular attribute, whereas in others they are requisite if the document is to be ???well-formed???. The standard that a designer chooses is determined usually by the requirements specification document. This specifies which browsers and versions of those browsers that the web page is expected to correctly display. Forcing a hypertext document to conform strictly to a specific W3C standard for HTML is often no simple task. In the worst case, it cannot conform without losing some aesthetics or accessibility functionality. Second, the case of HTML documents is not an isolated case. Standards for XML, XSL, JavaScript, VBScript, are analogous. Therefore, you might imagine the problems when you begin to combine these languages and formats in an HTML document. Third, there is always more than one way to skin a cat. For example, Bobby and Cynthia may flag those IMG tags that do not contain a TITLE attribute. There might be good reason that a web developer chooses not to include the title attribute. The title attribute has a limited numbers of characters and does not support carriage returns. This is a major defect in the design of this tag. In fact, before the TITLE attribute was supported, there was the ALT attribute. Most browsers support both, yet they both perform a similar function. However, both attributes share the same deficiencies. In practice, there are instances where neither attribute would be used. Instead, for example, the developer would write some JavaScript or VBScript to circumvent these deficiencies. The concern is that Bobby and Cynthia would not notice this because it does not ???understand??? what the JavaScript does. </Description> <Keywords>unused</Keywords> <Title>unused</Title> </Seo> </row> </rows> </root> EDIT Here are my entities: public class LitePropertyData { public virtual string Description { get; set; } public virtual bool DisplayEditUI { get; set; } public int OwnerTab { get; set; } public virtual string DisplayName { get; set; } public int FieldOrder { get; set; } public bool IsRequired { get; set; } public string Name { get; set; } public virtual bool IsModified { get; set; } public virtual int ParentPageID { get; set; } public LiteDataType Type { get; set; } public object Value { get; set; } } [Serializable] public class LitePageData { public String Guid { get; set; } public Int32 ID { get; set; } public String Name { get; set; } public Int32? ParentID { get; set; } public DateTime Created { get; set; } public String CreatedBy { get; set; } public DateTime Changed { get; set; } public String ChangedBy { get; set; } public Int32? LitePageTypeID { get; set; } public String Html { get; set; } public String FriendlyName { get; set; } public Boolean IsDeleted { get; set; } public List<LitePropertyData> Properties { get; set; } public LiteSeoPageData Seo { get; set; } /// <summary> /// Saves the specified XML full file path. /// </summary> /// <param name="xmlFullFilePath">The XML full file path.</param> public void Save(String xmlFullFilePath) { XDocument doc = XDocument.Load(xmlFullFilePath); XElement demoNode = this.ToXElement<LitePageData>(); demoNode.Name = "row"; doc.Descendants("rows").Single().Add(demoNode); doc.Save(xmlFullFilePath); } }

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  • Google Rules for Retail

    - by David Dorf
    In the book What Would Google Do?, Jeff Jarvis outlines ten "Google Rules" that define how Google acts.  These rules help define how Web 2.0 businesses operate today and into the future.  While there's a chapter in the book on applying these rules to the retail industry, it wasn't very in-depth.  So I've decided to more directly apply the rules to retail, along with some notable examples of success.  The table below shows Jeff's Google Rule, some Industry Examples, and New Retailer Rules that I created. Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} table.MsoTableGrid {mso-style-name:"Table Grid"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-priority:59; mso-style-unhide:no; border:solid black 1.0pt; mso-border-themecolor:text1; mso-border-alt:solid black .5pt; mso-border-themecolor:text1; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-border-insideh:.5pt solid black; mso-border-insideh-themecolor:text1; mso-border-insidev:.5pt solid black; mso-border-insidev-themecolor:text1; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} Google Rule Industry Examples New Retailer Rule New Relationship Your worst customer is your friend; you best customer is your partner Newegg.com lets manufacturers respond to customer comments that are critical of the product, and their EggXpert site lets customers help other customers. Listen to what your customers are saying about you.  Convert the critics to fans and the fans to influencers. New Architecture Join a network; be a platform Tesco and BestBuy released APIs for their product catalogs so third-parties could create new applications. Become a destination for information. New Publicness Life is public, so is business Zappos and WholeFoods founders are prolific tweeters/bloggers, sharing their opinions and connecting to customers.  It's not always pretty, but it's genuine. Be transparent.  Share both your successes and failures with your customers. New Society Elegant organization Wet Seal helps their customers assemble outfits and show them off to each other.  Barnes & Noble has a community site that includes a bookclub. Communities of your customers already exist, so help them organize better. New Economy Mass market is dead; long live the mass of niches lululemon found a niche for yoga inspired athletic wear.  Threadless uses crowd-sourcing to design short-runs of T-shirts. Serve small markets with niche products. New Business Reality Decide what business you're in When Lowes realized catering to women brought the men along, their sales increased. Customers want experiences to go with the products they buy. New Attitude Trust the people and listen In 2008 Starbucks launched MyStartbucksIdea to solicit ideas from their customers. Use social networks as additional data points for making better merchandising decisions. New Ethic Be honest and transparent; don't be evil Target is giving away reusable shopping bags for Earth Day.  Kohl's has outfitted 67 stores with solar arrays. Being green earns customers' respect and lowers costs too. New Speed Life is live H&M and Zara keep up with fashion trends. Be prepared to pounce on you customers' fickle interests. New Imperatives Encourage, enable and protect innovation 1-800-Flowers was the first do sales in Facebook and an early adopter of mobile commerce.  The Sears Personal Shopper mobile app finds products based on a photo. Give your staff permission to fail so innovation won't be stifled. Jeff will be a keynote speaker at Crosstalk, our upcoming annual user conference, so I'm looking forward to hearing more of his perspective on retail and the new economy.

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