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  • Web Service gets unavailable after several concurrent calls

    - by Roman
    We are testing GoDaddy Virtual Data Center and came to a very strange issue when our web site gets unavailable. GoDaddy Support keeps saying the issue is in our web server settings, but looking at the result of our tests I doubt it. TEST ENVIRONMENT Virtual DataCenter with Windows hosted at GoDaddy.com. All servers have Windows Server 2008 R2 Datacenter, IIS 7. Server One with IP address 10.1.0.4 Server Two with IP address 10.1.0.3 Both servers are in private network not visible from outside. Port Forward with IP address 50.62.13.174. Port Forward is assigned to Server One TEST DESCRIPTION JMeter is used as a Client App to simulate 30 concurrent users sending 100 SOAP requests each. Interval between requests is 1 second. Http link used for testing: http://50.62.13.174/v2/webservices.asmx TEST ONE Test is run from a computer in our office. After JMeter starts running test, almost immediately, the link above becomes unavailable in a browser. After test completion, the link is not available in a browser for about 5 more minutes. Remote Desktop is working well, so we can connect to Server One remotely. After about 5 minutes since test completion, the link becomes available in a browser again. TEST TWO Test is run from Server Two (that is part of our virtual data center). Test works very well, no visible delays in processing. The link is available in a browser all the time. TEST THREE Test is run from Server One using localhost. The result is the same as in TEST TWO - no issues. TEST FOUR We repeated TEST ONE from other computers that we have located in different countries, all with the same result as TEST ONE. CONCLUSION As the test works well from Server Two, but does not work from outside our virtual data center, we feel there are issues with the network or its capacity. The whole behaviour looks like out requests from outside get stuck somewhere before reaching our virtual data center. Has anybody had similar issues in the past? Are there chances that something is wrong with our server settings?

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  • mint linux, DVD drive keeps randomly being accessed. unsure how to find culprit

    - by juicebox
    I have a workstation with mint linux 12. It seems like the DVD drive on the machine keeps randomly "activating". By activating it makes noise, the light turns on, and it seems like it is checking if a disk is in it. At first I thought I was being hacked and someone/something was trying to check if I had media in the DVDRom drive. I ruled that out with netstat and rkhunter. I checked my logs and the only thing I can find that might help point out the problem are these repeated chunks in syslog: Mar 24 17:47:31 rich-MINT kernel: [ 9846.551422] ata2.00: cmd a0/00:00:00:08:00/00:00:00:00:00/a0 tag 0 pio 16392 in Mar 24 17:47:31 rich-MINT kernel: [ 9846.551424] res 51/40:01:00:00:00/00:00:00:00:00/a0 Emask 0x10 (ATA bus error) Mar 24 17:47:31 rich-MINT kernel: [ 9846.551427] ata2.00: status: { DRDY ERR } Mar 24 17:47:31 rich-MINT kernel: [ 9846.551433] ata2.00: hard resetting link Mar 24 17:47:32 rich-MINT kernel: [ 9846.868012] ata2.01: hard resetting link Mar 24 17:47:32 rich-MINT kernel: [ 9847.344054] ata2.00: SATA link up 1.5 Gbps (SStatus 113 SControl 310) Mar 24 17:47:32 rich-MINT kernel: [ 9847.344067] ata2.01: SATA link up 3.0 Gbps (SStatus 123 SControl 300) Mar 24 17:47:32 rich-MINT kernel: [ 9847.376118] ata2.00: configured for PIO0 Mar 24 17:47:32 rich-MINT kernel: [ 9847.393047] ata2.01: configured for UDMA/133 Mar 24 17:47:32 rich-MINT kernel: [ 9847.397046] ata2: EH complete and again Mar 24 17:55:28 rich-MINT kernel: [10323.633268] sr 1:0:0:0: ioctl_internal_command return code = 8000002 Mar 24 17:55:28 rich-MINT kernel: [10323.633270] : Sense Key : Aborted Command [current] [descriptor] Mar 24 17:55:28 rich-MINT kernel: [10323.633275] : Add. Sense: No additional sense information Mar 24 17:55:11 rich-MINT kernel: [10306.640009] ata2.00: link is slow to respond, please be patient (ready=0) Mar 24 17:55:16 rich-MINT kernel: [10310.840009] ata2.00: SRST failed (errno=-16) Mar 24 17:55:16 rich-MINT kernel: [10310.840016] ata2.00: hard resetting link Mar 24 17:55:16 rich-MINT kernel: [10311.160013] ata2.01: hard resetting link Mar 24 17:55:16 rich-MINT kernel: [10311.636061] ata2.00: SATA link up 1.5 Gbps (SStatus 113 SControl 310) Mar 24 17:55:16 rich-MINT kernel: [10311.636075] ata2.01: SATA link up 3.0 Gbps (SStatus 123 SControl 300) Mar 24 17:55:16 rich-MINT kernel: [10311.668122] ata2.00: configured for PIO0 Mar 24 17:55:16 rich-MINT kernel: [10311.684854] ata2.01: configured for UDMA/133 Mar 24 17:55:17 rich-MINT kernel: [10312.105473] ata2: EH complete (Copied from Pastebin - http://pastebin.com/YNDrnyzH) If any linux masters could take a quick look at these log outputs and help me understand what is going on , much appreciated.

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  • No Telnet login prompt when used over SSH tunnel

    - by SCO
    Hi there ! I have a device, let's call it d1, runnning a lightweight Linux. This device is NATed by my internet box/router, hence not reachable from the Internet. That device runs a telnet daemon on it, and only has root as user (no pwd). Its ip address is 192.168.0.126 on the private network. From the private network (let's say 192.168.0.x), I can do: telnet 192.168.0.126 Where 192.168.0.126 is the IP address in the private network. This works correctly. However, to allow administration, I'd need to access that device from outside of that private network. Hence, I created an SSH tunnel like this on d1 : ssh -R 4455:localhost:23 ussh@s1 s1 is a server somewhere in the private network (but this is for testing purposes only, it will endup somewhere in the Internet), running a standard Linux distro and on which I created a user called 'ussh'. s1 IP address is 192.168.0.48. When I 'telnet' with the following, let's say from c1, 192.168.0.19 : telnet -l root s1 4455 I get : Trying 192.168.0.48... Connected to 192.168.0.48. Escape character is '^]'. Connection closed by foreign host . The connection is closed after roughly 30 seconds, and I didn't log. I tried without the -l switch, without any success. I tried to 'telnet' with IP addresses instead of names to avoid reverse DNS issues (although I added to d1 /etc/hosts a line refering to s1 IP/name, just in case), no success. I tried on another port than 4455, no success. I gathered Wireshark logs from s1. I can see : s1 sends SSH data to c1, c1 ACK s1 performs an AAAA DNS request for c1, gets only the Authoritave nameservers. s1 performs an A DNS request, then gets c1's IP address s1 sends a SYN packet to c1, c1 replies with a RST/ACK s1 sends a SYN to c1, C1 RST/ACK (?) After 0.8 seconds, c1 sends a SYN to s1, s1 SYN/ACK and then c1 ACK s1 sends SSH content to d1, d1 sends an ACK back to s1 s1 retries AAAA and A DNS requests After 5 seconds, s1 retries a SYN to c1, once again it is RST/ACKed by c1. This is repeated 3 more times. The last five packets : d1 sends SSH content to s1, s1 sends ACK and FIN/ACK to c1, c1 replies with FIN/ACK, s1 sends ACK to c1. The connection seems to be closed by the telnet daemon after 22 seconds. AFAIK, there is no way to decode the SSH stream, so I'm really stuck here ... Any ideas ? Thank you !

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  • Server currently under DDOS, not sure what to do.

    - by Volex
    Hi, My web server is currently under a DDOS attack I believe, the messages log is full of these kind of messages: May 13 15:51:19 kernel: nf_conntrack: table full, dropping packet. May 13 15:51:19 last message repeated 9 times May 13 15:51:24 kernel: __ratelimit: 78 callbacks suppressed May 13 15:51:24 kernel: nf_conntrack: table full, dropping packet. May 13 15:52:06 kernel: possible SYN flooding on port 80. Sending cookies. and a netstat has a huge amount of the following: tcp 0 0 my.host.com:http bb176da0.virtua.com.br:4998 SYN_RECV tcp 0 0 my.host.com:http 187.0.43.109:2694 SYN_RECV tcp 0 0 my.host.com:http 109.229.4.145:1722 SYN_RECV tcp 0 0 my.host.com:http 189-84-163-244.sodobr:63267 SYN_RECV tcp 0 0 my.host.com:http bd66839d.virtua.com.br:3469 SYN_RECV tcp 0 0 my.host.com:http 69.101.56.190.dsl.int:52552 SYN_RECV tcp 0 0 my.host.com:http pc-62-230-47-190.cm.vt:2262 SYN_RECV tcp 0 0 my.host.com:http 189-84-163-244.sodobr:63418 SYN_RECV tcp 0 0 my.host.com:http pc-62-230-47-190.cm.vt:1741 SYN_RECV tcp 0 0 my.host.com:http zaq3d739320.zaq.ne.jp:2141 SYN_RECV tcp 0 0 my.host.com:http netacc-gpn-4-80-73.po:52676 SYN_RECV tcpdump shows: 7:11:08.564510 IP 187-4-1xx-4.xxx.ipd.brasiltelecom.net.br.54821 my.host.com.http: S 999692166:999692166(0) win 65535 17:11:08.566347 IP 114-44-171-67.dynamic.hinet.net.1129 my.host.com.http: S 605369055:605369055(0) win 65535 17:11:08.570210 IP 200-101-13-130.pvoce300.ipd.brasiltelecom.net.br.5590 my.host.com.http: S 2813379182:2813379182(0) win 16384 17:11:08.571290 IP dsl-189-143-30-99-dyn.prod-infinitum.com.mx.1615 my.host.com.http: S 281542700:281542700(0) win 65535 17:11:08.583847 IP dsl-189-143-30-99-dyn.prod-infinitum.com.mx.1617 my.host.com.http: S 499413892:499413892(0) win 65535 17:11:08.588680 IP 170.51.229.112.2569 my.host.com.http: S 2195084898:2195084898(0) win 65535 17:11:08.588773 IP gw2-1.211.ru.3180 my.host.com.http: F 2315901786:2315901786(0) ack 2620913033 win 64240 17:11:08.590656 IP 200-101-13-130.pvoce300.ipd.brasiltelecom.net.br.5614 my.host.com.http: S 2813715032:2813715032(0) win 16384 17:11:08.591212 IP 203.82.82.54.15848 my.host.com.http: S 4070423507:4070423507(0) win 16384 17:11:08.591254 IP 203.82.82.54.2545 my.host.com.http: S 1790910784:1790910784(0) win 16384 17:11:08.591289 IP 203.82.82.54.28306 my.host.com.http: S 578615626:578615626(0) win 16384 17:11:08.591591 IP gw2-1.211.ru.3191 my.host.com.http: F 2316435991:2316435991(0) ack 2634205972 win 64240 17:11:08.591790 IP 200-101-13-130.pvoce300.ipd.brasiltelecom.net.br.5593 my.host.com.http: S 2813659017:2813659017(0) win 16384 17:11:08.593691 IP gw2-1.211.ru.3203 my.host.com.http: F 2316834420:2316834420(0) ack 2629074987 win 64240 I'm not sure what I can do to limit/mitigate this, currently no webpages are being served, any help gratefully appreciated.

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  • AWS EC2 - How to specify an IAM role for an instance being launched via awscli

    - by Skaperen
    I am using the "aws ec2 run-instances" command (from the awscli package) to launch an instance in AWS EC2. I want to set an IAM role on the instance I am launching. The IAM role is configured and I can use it successfully when launching an instance from the AWS web UI. But when I try to do this using that command, and the "--iam-instance-profile" option, it failed. Doing "aws ec2 run-instances help" shows Arn= and Name= subfields for the value. When I try to look up the Arn using "aws iam list-instance-profiles" it gives this error message: A client error (AccessDenied) occurred: User: arn:aws:sts::xxxxxxxxxxxx:assumed-role/shell/i-15c2766d is not authorized to perform: iam:ListInstanceProfiles on resource: arn:aws:iam::xxxxxxxxxxxx:instance-profile/ (where xxxxxxxxxxxx is my AWS 12-digit account number) I looked up the Arn string via the web UI and used that via "--iam-instance-profile Arn=arn:aws:iam::xxxxxxxxxxxx:instance-profile/shell" on the run-instances command, and that failed with: A client error (UnauthorizedOperation) occurred: You are not authorized to perform this operation. If I leave off the "--iam-instance-profile" option entirely, the instance will launch but it will not have the IAM role setting I need. So the permission seems to have something to do with using "--iam-instance-profile" or accessing IAM data. I repeated several times in case of AWS glitches (they happen sometimes) and no success. I suspected that perhaps there is a restriction that an instance with an IAM role is not allowed to launch an instance with a more powerful IAM role. But in this case, the instance I am doing the command in has the same IAM role that I am trying to use. named "shell" (though I also tried using another one, no luck). Is setting an IAM role not even permitted from an instance (via its IAM role credentials)? Is there some higher IAM role permission needed to use IAM roles, than is needed for just launching a plain instance? Is "--iam-instance-profile" the appropriate way to specify an IAM role? Do I need to use a subset of the Arn string, or format it in some other way? Is it possible to set up an IAM role that can do any IAM role accesses (maybe a "Super Root IAM" ... making up this name)? FYI, everything involves Linux running on the instances. Also, I am running all this from an instance because I could not get these tools installed on my desktop. That and I do not want to put my IAM user credentials on any AWS storage as advised by AWS here. after answered: I did not mention the launching instance permission of "PowerUserAccess" (vs. "AdministratorAccess") because I did not realize additional access was needed at the time the question was asked. I assumed that the IAM role was "information" attached to the launch. But it really is more than that. It is a granting of permission.

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  • Concatenation of a 2 second silence audio with a normal audio not working

    - by user1665130
    I have a code for concatenation of files using ffmpeg.Here silence.wav is a mute audio file with 2 seconds length. I need to prepend this mut audio file to REC00096_Jun-06-2014 16.47.28.wav. I tried the folowing code. ffmpeg -i D:\vishnu\silence.wav -i D:\vishnu\REC00096_Jun-06-2014 16.47.28.wav \-filter_complex '[0:0][1:0][2:0][3:0]concat=n=2:v=0:a=1[out]' \-map '[out]' output.wav Following is the error i am getting. D:\vishnu>ffmpeg -i silence.wav -i "D:\vishnu\REC00096_Jun-06-2014 16.47.28.wav" -filter_complex '[0:0][1:0][2:0][3:0]concat=n=2:v=0:a=1[out]' -map '[out]' outp ut.wav ffmpeg version N-59036-g5d8e4f6 Copyright (c) 2000-2013 the FFmpeg developers built on Dec 12 2013 22:01:01 with gcc 4.8.2 (GCC) configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab le-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetyp e --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --ena ble-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-l ibopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libsp eex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aa cenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavp ack --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib libavutil 52. 58.100 / 52. 58.100 libavcodec 55. 45.101 / 55. 45.101 libavformat 55. 22.100 / 55. 22.100 libavdevice 55. 5.102 / 55. 5.102 libavfilter 3. 92.100 / 3. 92.100 libswscale 2. 5.101 / 2. 5.101 libswresample 0. 17.104 / 0. 17.104 libpostproc 52. 3.100 / 52. 3.100 Input #0, wav, from 'silence.wav': Metadata: encoder : Lavf55.22.100 Duration: 00:00:02.02, bitrate: 4234 kb/s Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, 5.1, s16, 4 233 kb/s Guessed Channel Layout for Input Stream #1.0 : mono Input #1, wav, from 'D:\vishnu\REC00096_Jun-06-2014 16.47.28.wav': Duration: 00:00:08.04, bitrate: 384 kb/s Stream #1:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 24000 Hz, mono, s16, 384 kb/s [wav @ 036f5e40] Invalid stream specifier: '[out]'. Last message repeated 1 times Stream map ''[out]'' matches no streams. D:\vishnu>

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  • hyperv machine guest loads slow

    - by Dani Avni
    this is by far one of the strangest things I have seen. I have a win 2008R2 cluster with a CSV. the CSV itself is on an iSCSI storage (hitachi HUS 110) basic config of the two hosts in the cluster is Dell R610 Win 2008 R2 with all patches 64GB 1 NIC for host access 2 NICs for guest access 2 NICs for iSCSI these machine work great and I can load a 2008R2 test guest machine on them in less than 90 seconds after the above config is running for over a year, I now need to add a new host. now the host is Dell R620 (Still intel but different CPU) Win 2008 R2 with all patches 64GB 1 NIC for host access 2 NICs for guest access 2 NICs for iSCSI I added this new host to the domain and to the cluster, I gave it access to the CSV and I tried loading the same guest machine that loads in 90 seconds in the other hosts. the machine loads in about 6 minutes. no matter how many times I try this the old hosts load the machine in about 90 seconds and this new host in around 6 minutes to eliminate any problems with the iSCSI connection, I added a new LUN and directly accessed it from the new host and I was working at around 300MB/s so no problem there. I also tested the connection between the other hosts and the new one and network is working fine there too. to eliminate problems in HyperV, I copied the machine to the local disk of the new host and it loaded in less than 20 seconds. now is the point were things get a lot stranger: in my tests I tried installing a fresh windows guest machine to the CSV from the new host. I noticed that while the fresh windows was installing, my test guest was loading in less than 90 seconds even on the new host (I repeated this a few times). If I paused the fresh install guest and tried loading the test guest again it loaded in 6 minutes. and again after I resumed the guest installation the test guest loaded fast. after the fresh windows was also loaded, I ran tests loading the fresh window and my test machine. each one of them loaded in about 5 minutes when I tried loading them separately. however when I started both of them in the same time they both loaded in around 2.5 minutes it seems that the iSCSI disk access is only working if it is under some load (although I never got to above 10% utilization according to the task manager) does anyone have any idea what could be the problem?

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  • Event ID 17890 (A significant part... paged out.) with SQL Server 2008

    - by Godeke
    I have a machine that has SQL Server 2008 Standard installed. Periodically (about once an hour) I am getting Event ID 17890 several times in a row. An example: 6:28:54 "A significant part of sql server process memory has been paged out. This may result in a performance degradation. Duration: 0 seconds. Working set (KB): 10652, committed (KB): 628428, memory utilization: 1%%. 6:34:27 "A significant part of sql server process memory has been paged out. This may result in a performance degradation. Duration: 332 seconds. Working set (KB): 169780, committed (KB): 546124, memory utilization: 31%%." 6:38:55 "A significant part of sql server process memory has been paged out. This may result in a performance degradation. Duration: 600 seconds. Working set (KB): 245068, committed (KB): 546124, memory utilization: 44%%." This pattern repeated at 7:26 - 7:37, 8:26 - 8:36, 9:24 - 9:35 and so with the same increasing working set and memory utilization pattern. I don't have any (known) background tasks running at this time. Backups run at 2:00 This subsided from 11:00 at night until it resumed at 4:00 in the morning and has been continuing the intermittent 10 minute glitch periods. As this server has plenty of RAM (the commit charge has peaked at 2,871,564 of 4,194,012 physical) I disabled the paging files after reading several items I dug up searching Google and not finding any of them changing the situation. This pattern I am documented is after removing the paging files, so I'm not even sure where we are paging the SQL process could be going. I also changed the SQL process memory to have a minimum of 500MB and a maximum of 2GB of RAM (as this is a light duty database server serving only a small workgroup). Has anyone encountered this? Prior to disabling the page files this error would cause 5 minutes of disk thrashing that disabled access to the databases, files, IIS webs and so on. Since disabling the page files it just logs strange things, but I'm not seeing a performance drop at least. Any suggestions would be welcome.

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  • Old CRT screen's high resolution doesn't work anymore on windows 7

    - by Mixxiphoid
    One year ago I decided to switch from Windows XP to Windows 7. I had a 17" CRT monitor with a screen resolution of 1600x1200 which worked fine on Windows XP. While installing Windows 7 everything went well until Windows 7 was going to install the video card its driver. Windows 7 puts the screen to its recommended resolution and my screen became black. I waited a few minutes to be sure the installation was finished. I turned off the computer by hand and restarted the computer on a resolution of 800x640. When windows 7 was done installing I went to screen resolutions and the resolution of 1600x1200 was on the top of the list with '(recommended)' next to it. I tried putting it on 1600x1200 but again my screen went black. I installed all windows 7 updates including the video card driver from the NVidia site (NOT from Windows 7). I tried about everything to make it work on 1600x1200 but with no succes. The highest resolution I got with the crt monitor was 1280x1024. I had a TFT screen which had 1280x1024 as max resolution and had better colors, so I used that one till today. My video card is 9600GT and my power supply is beyond sufficient. I even tried to install the driver I had on XP to see if it worked, but no results. I tried classic mode on windows 7, changed the dpi, the frequentie and the monitor settings, but nothing worked. I really like a vertical resolution of 1200, but it seems today I'm bound to all those standard monitors with a resolution of 1980x1024... Can anybody explain to me what the cause is that it worked on Windows XP but not on Windows 7? And maybe a solution to the problem (I actually gave up on getting it fixed...) Thanks a lot in advance. SOLUTION I downloaded the according monitor driver and installed it. Next I rebooted my computer on low resolution (800x640) and connected the CRT monitor. When Windows 7 booted successfully I went to computer management and 'update the driver' of my monitor. I manually selected 'Generic PnP monitor' and made that one active. I want to advanced settings at 'Screen resolution' and selected the mode '1600x1200 (32-bit) 80 Hertz (95 Hertz did not work). Now I had my resolution on 1600x1200. I repeated the earlier step to select the original monitor again instead of the Generic monitor. Quite a way to solve this problem, but it worked! Thanks a lot you all.

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  • PHP hits 100% CPU and eats RAM at the same time Monday to Friday

    - by Daniel Samuels
    We run a learning platform for primary schools here in the UK and it's all been running extremely well. However at around 4PM Monday to Friday we see the same issue arise -- 1-2 PHP threads will spike to 100% CPU and gradually start eating up RAM until the server(s) fall over. 98%+ of our requests are HTTPS, these come into our Layer 7 load balancer which then decrypts the SSL data, adds the X-HTTP-Forwarded-For header and forwards the data onto an application server (we have 2 of those at the moment) on port 80. Our application servers have Varnish on port 80 which takes in the request from the load balancer and passes the request through to Nginx on port 81. Nginx then works out which 'vhost' it needs to use and passes any PHP processing through to PHP-CGI which is listening on a socket (managed through spawn-fcgi). There's an instance of Memcached running too, MySQL runs on a separate server / slave setup. Throughout the day the load will typically go no higher than 0.8 on either of the application servers, however at around 4PM our problem arises. I've managed to run strace on a few of the actual threads when they cause the problem and I always see the same thing: stat("/usr/share/zoneinfo/Europe/London", {st_mode=S_IFREG|0644,st_size=3661, ...}) = 0 stat("/usr/share/zoneinfo/Europe/London", {st_mode=S_IFREG|0644,st_size=3661, ...}) = 0 This is repeated infinitely and never stops until you SEGKILL the process or oomkiller kills it. There are no cron jobs scheduled to run at that time and I don't have any way of seeing exactly what Nginx request is associated with the PHP process which is running. We are running PHP 5.3.14 which we upgraded to from 5.3.8 last week to rule out the older version being the problem. This issue has been going on a few months now and we have no idea what is causing it. We deploy our software very frequently, so it's difficult to track down a specific release which may have started the problem - especially as we do not know the date of the first occurrence of this issue. Varnish is version 3.0.1, Nginx is 1.0.6 (which I understand is about a year old now), our servers are running CentOS release 5.7 (Final) they have Intel i3 540s at 3.07Ghz and 8GB of RAM. There's a discussion on the Debian mailing list about something very similar, you can find that here. Has anyone seen anything like this in the past, does anyone have any ideas or suggestions? Are there a way of linking an Nginx request directly to a PHP thread? Is there a better way of seeing what the PHP process is doing? (I've seen GDB mentioned, though I'll have to recompile PHP) Thanks!

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  • VMware server 2.0 SYN/ACK repeating issues

    - by user65579
    VMWare Server 2.0.0 Build 122956 I am having some issues with connecting into a guest VM (Ubuntu linux 4.4.3-4 lucid) running under VMware 2.0 on a windows server host. All connections to and from the VM's work fine, except for FTP. I thought the issue was the FTP daemon at first but it has been ruled out that it is not the daemon or the server itself. When you try to connect to the FTP server from outside of the host OS it fails with a "421 Service not available" but when you try and connect from the local VM or from the host OS the connection goes through fine. I have ran many packet sniffs using wireshark/tcpdump from the VM, the host OS, and the client connecting, the most informative is the host OS. I have attached a PNG of the relavant packets that were captured. I viewed some other network traffic that was sniffed (WWW specifically) and it seems to do the same syn/ack repeating but the user doesnt see any issues. I have disabled the firewall and the issues persisits, I have tried with specific allow rules to ensure the data is allowed and no changes. It appears like VMware attempts to do the ICMP redirect and it works, but then it vmware repeats the packets sent so you get 3 syn/ack's for every one syn from the client. Also VMWare appears to be attempting to establish an FTP connection between the HOST OS and the GUEST OS, because I see the second SYN sent from the HOST OS to the GUEST to initiate a new connection, and it get the appropriate SYN/ACK followed by an ACK, but the client never sees any of this from its end. EG. syn from client syn/ack from host OS to client syn/ack from guest OS to client syn/ack from host OS to client The same thing happens when the connection reset is attempted, RST's start being sent and repeated, the server responds with a valid header to continue the FTP handshake but the RST acknowledgement is allready issued and things are closed. I am not 100% if this is a bug in VMware or possibly a VMNetwork missconfiguration. Does anyone have any thoughts on where exactly the issue could be, things to try to verify or rule out? I have linked to a picture of the relevant packets sniffed from the host OS. http://img18.imageshack.us/img18/7789/vmwareftpconnection.jpg

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  • GPU not powering on

    - by Lerp
    So I got home from work yesterday and went to turn my computer on as per usual to be greeted by this: The screens remained black, so I rebooted; I go as far as GRUB before my screens went black again. I rebooted again, they didn't turn on. I rebooted again, I got as far as the windows login screen. This time I unplugged it, opened it up and cleaned it but to no luck. The GPU was still being tempermental. I repeated the process of turning off and on several times until one time it work as normal. I happily played games for the rest of the night (5-6 hours?) thinking everything was jolly good now. Well I get home from work today and it is doing the SAME thing. Sometimes everything displays normally for a few seconds to minutes then the screens go black; then sometimes the screens don't come on at all. Summary and additional points Screens sometimes turn on before shortly turning off, sometimes they don't; I cannot seem to determine any pattern between when they do or do not turn off. The build has been working fine for about 8 months now so I know it's not hardware incompatibility. If I plug a monitor into the on board graphics I can use the PC normally (just in low graphics mode) I have two monitors and it's a case of they both turn on or not. So I think I can rule out the monitors being dead. I have tried replacing the GPU I have tried replacing the RAM I have tried flashing the CMOS I have tried cleaning the inside The GPU is a Radeon HD 7870 My questions Is my GPU dead? It's not very old and I would rather have a method of being certain it's the GPU before I fork out some money I can't really afford. I do not have a second PC here to test it in. If my GPU is dead why does it sometimes work and sometimes not? Update Okay, it was working again.. at least I thought it was. I left it running for 10-20minutes with the screens black. Turned it off and straight back on and it worked for all of 10minutes. I was then updating the post in joy thinking I could play some games for the rest of the night when BAM it went black again. So yeah, I don't know :C

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  • How to encrypt dual boot windows 7 and xp (bitlocker, truecrypt combo?) on sdd (recommended?)

    - by therobyouknow
    I would like to setup a dual boot Windows 7 and Windows XP laptop/notebook computer where each operation system's partition is fully encrypted. I would like to do this on a SSD - a 128Gb Crucial M4. My research Dual boot of truecrypt encrypted OSs on one drive (not possible - in Truecript 7.x at time of writing) This cannot be done on a standard Truecrypt setup - it will only support encrypting one of the operating systems. I have tried this and also read about it here on superuser.com However, I did see a solution here that uses grub4dos as the initial bootloader to chain to separate truecrypt encrypted OSs, in my case Windows 7 and Windows XP: http://yyzyyz.blogspot.co.uk/2010/06/truecrypt-how-to-encrypt-multiple.html I am not going to consider this solution as it relies upon some custom code for use in the bootloader that is provided by the author. I would prefer a solution that can be fully understood so that I can be sure that there is nothing undesirable occuring (i.e. malware or just simply bugs in the code). I would like to believe such a solution doesn't have those risks but I can't be sure. BitLocker and Truecrypt combination - possible solution? So I am now considering a combination of encryption programs: I now aim to encrypt Windows XP with Truecrypt and Windows 7 with BitLocker. Assuming Truecrypt bootloader can boot into non-Truecrypt OSs (e.g. via hitting Escape to go to another menu), then this solution may be viable. SSDs and Encryption (use fastest possible spinning hard disk instead (?)) I read on various superuser.com posts and elsewhere that current SSDs are not suited to whole drive encryption for various reasons: impact of performance algorithms that give SSDs advantage over spinning harddisks. Algorithms used in compression of data for example. Wear on the SSD, shortening its life Security issues whereby data is repeated, as indicated in some Truecrypt documentation So I am now considering not using SSD. But with the aim to have the fastest drive possible, I am considering using the Western Digital Scorpion black 2.5" 7200rpm harddisk as this appears to be top rated among spinning platter-based harddrives (don't work for Western Digital). Summary So to achieve whole drive encrypted dual boot Windows 7 and Windows XP with minimal performance impact I intend to use a combination of Truecrypt and Bitlocker on a top-rated conventional spinning platter-based harddisk. Questions Will my summary: achieve whole disk encryption of the dual-boot Windows XP, Windows 7? OR an you suggest a simpler solution, including one that only requires only Truecrypt (BitLocker not available on XP). Or another encryption tool, including paid-for? provide the highest performance. Am I correct to avoid using SDD with encryption for the reasons I discovered? Are the concerns about SSDs and encryption still very real (some articles I read go back to 2010) Thanks for your input!

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  • I have been told to accept one error with Memtest86+

    - by DustByte
    Bought a new computer back in August with 4x4 GB RAM. Had problems with the RAM. They sent me four new sticks, which also generated errors. Singled out four sticks (from the eight I now had) that didn't generate any errors. Discovered by coincident a new RAM error last week (this time no BSOD). Contacted the company. According to them there have been issues with a bad stock from last summer so I got two tested 8 GB sticks sent to me. Been running Memtest86+ over the weekend. After 20 hours I got an error (see attached photo). The test has now been running for 37 hours but so far only this one error. I contacted the company where I bought the computer. They wrote back: I wouldn't worry about hat one fail. We have had similar situations here whereby it passes numerous times but then fails once. We think it's an issue with memtest, after all memory is faulty or it isn't so you can't really have it pass a few times, fail the next time around and then pass again! Please trust me on this and continue with the memory we sent you and if your problems continue we'll look at getting it replaced again. I gather from other forum posts that many people do not accept a single error. What could this single error signify, faulty RAM or a glitch in the MEMTEST program (or other)? Update: From the helpful comments below I conclude that an occasional (and rare) "random" error could occur and be acceptable, but repeated errors at the same address would indicate malfunction. Memtest has now run for 45 hours and I still have only one error. For everyone's information, I will keep running the test. In less than two days I am going away for a month. I will most likely leave Memtest running. As I do not have a UPS there is a risk that a power outage will ruin the experiment. The computer is a desktop so I cannot bring it with me (which would curiously have exposed it to more cosmic rays as I will be flying ;)).

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  • Weird nfs performance: 1 thread better than 8, 8 better than 2!

    - by Joe
    I'm trying to determine the cause of poor nfs performance between two Xen Virtual Machines (client & server) running on the same host. Specifically, the speed at which I can sequentially read a 1GB file on the client is much lower than what would be expected based on the measured network connection speed between the two VMs and the measured speed of reading the file directly on the server. The VMs are running Ubuntu 9.04 and the server is using the nfs-kernel-server package. According to various NFS tuning resources, changing the number of nfsd threads (in my case kernel threads) can affect performance. Usually this advice is framed in terms of increasing the number from the default of 8 on heavily-used servers. What I find in my current configuration: RPCNFSDCOUNT=8: (default): 13.5-30 seconds to cat a 1GB file on the client so 35-80MB/sec RPCNFSDCOUNT=16: 18s to cat the file 60MB/s RPCNFSDCOUNT=1: 8-9 seconds to cat the file (!!?!) 125MB/s RPCNFSDCOUNT=2: 87s to cat the file 12MB/s I should mention that the file I'm exporting is on a RevoDrive SSD mounted on the server using Xen's PCI-passthrough; on the server I can cat the file in under seconds ( 250MB/s). I am dropping caches on the client before each test. I don't really want to leave the server configured with just one thread as I'm guessing that won't work so well when there are multiple clients, but I might be misunderstanding how that works. I have repeated the tests a few times (changing the server config in between) and the results are fairly consistent. So my question is: why is the best performance with 1 thread? A few other things I have tried changing, to little or no effect: increasing the values of /proc/sys/net/ipv4/ipfrag_low_thresh and /proc/sys/net/ipv4/ipfrag_high_thresh to 512K, 1M from the default 192K,256K increasing the value of /proc/sys/net/core/rmem_default and /proc/sys/net/core/rmem_max to 1M from the default of 128K mounting with client options rsize=32768, wsize=32768 From the output of sar -d I understand that the actual read sizes going to the underlying device are rather small (<100 bytes) but this doesn't cause a problem when reading the file locally on the client. The RevoDrive actually exposes two "SATA" devices /dev/sda and /dev/sdb, then dmraid picks up a fakeRAID-0 striped across them which I have mounted to /mnt/ssd and then bind-mounted to /export/ssd. I've done local tests on my file using both locations and see the good performance mentioned above. If answers/comments ask for more details I will add them.

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  • mdadm raid1 fails to resync

    - by JuanD
    Hello, I'm trying to solve this problem I'm having with an mdadm raid1. I have an ubuntu 9.04 server running on a software 2-drive raid1 with mdadm. Yesterday, one of the drives failed, and so I replaced it with a brand new drive of the same size. I removed the faulty drive, copied the partition from the remaining good drive to the new drive and then added it to the raid. It re-synced and the system worked fine, until the drive that hadn't failed, was also labeled failed. Now I had the raid running solely on the new drive. So I purchased another drive and repeated the procedure above. So now I had 2 brand new drives and the raid was syncing. However, after a few minutes I checked /proc/mdstat and the raid was no longer syncing. mdadm --detail /dev/md1 shows: (sdb is the first new drive, and sdc is the second new drive) root@dola:/home/jjaramillo# mdadm --detail /dev/md1 /dev/md1: Version : 00.90 Creation Time : Sat Dec 20 00:42:05 2008 Raid Level : raid1 Array Size : 974711680 (929.56 GiB 998.10 GB) Used Dev Size : 974711680 (929.56 GiB 998.10 GB) Raid Devices : 2 Total Devices : 2 Preferred Minor : 1 Persistence : Superblock is persistent Update Time : Wed Jun 2 10:09:35 2010 State : clean, degraded Active Devices : 1 Working Devices : 2 Failed Devices : 0 Spare Devices : 1 UUID : bba497c6:5029ba0b:bfa4f887:c0dc8f3d Events : 0.5395594 Number Major Minor RaidDevice State 2 8 35 0 spare rebuilding /dev/sdc3 1 8 19 1 active sync /dev/sdb3 I've tried removing and re-adding the drive a few times, but the same thing happens. The raid fails to resync. I've looked at /var/log/messages, and found the following: Jun 2 07:57:36 dola kernel: [35708.917337] sd 5:0:0:0: [sdb] Unhandled sense code Jun 2 07:57:36 dola kernel: [35708.917339] sd 5:0:0:0: [sdb] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE Jun 2 07:57:36 dola kernel: [35708.917342] sd 5:0:0:0: [sdb] Sense Key : Medium Error [current] [descriptor] Jun 2 07:57:36 dola kernel: [35708.917346] Descriptor sense data with sense descriptors (in hex): Jun 2 07:57:36 dola kernel: [35708.917348] 72 03 11 04 00 00 00 0c 00 0a 80 00 00 00 00 00 Jun 2 07:57:36 dola kernel: [35708.917357] 00 43 9e 47 Jun 2 07:57:36 dola kernel: [35708.917360] sd 5:0:0:0: [sdb] Add. Sense: Unrecovered read error - auto reallocate failed So it looks like there's some kind of error on sdb (the first new drive). My question is, what would be the best approach to get the raid up and running again? I've thought about dd'ing the /dev/md1 to a blank hard drive, then re-doing the raid from scratch and loading the data back, but there could be an easier solution.. Any help would be appreciated.

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  • Bluetooth DUN Tethering fails

    - by tacone
    I have an HTC Desire HD, with Android Froyo (2.2) and PDANet installed. I am using Ubuntu 10.10. I cannot tether it over Bluetooth either with Network Manager or BlueMan. (note, I installed Blueman only after failing with NetWork manager, and I even tried the last version from the PPA). With both my device is discovered, paired, setup. But connecting always fail. Network manager says it cannot get the details of my device Blueman says Connection Refused (111) Here are some relevant entries from syslog. Mar 11 22:13:00 tacone-macbook bluetoothd[2242]: Bluetooth deamon 4.69 Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: Starting SDP server Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: Starting experimental netlink support Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: Failed to find Bluetooth netlink family Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: Failed to init netlink plugin Mar 11 22:13:00 tacone-macbook kernel: [ 158.284357] Bluetooth: L2CAP ver 2.14 Mar 11 22:13:00 tacone-macbook kernel: [ 158.284361] Bluetooth: L2CAP socket layer initialized Mar 11 22:13:00 tacone-macbook kernel: [ 158.446781] Bluetooth: BNEP (Ethernet Emulation) ver 1.3 Mar 11 22:13:00 tacone-macbook kernel: [ 158.446784] Bluetooth: BNEP filters: protocol multicast Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: HCI dev 0 registered Mar 11 22:13:00 tacone-macbook kernel: [ 158.569481] Bluetooth: SCO (Voice Link) ver 0.6 Mar 11 22:13:00 tacone-macbook kernel: [ 158.569484] Bluetooth: SCO socket layer initialized Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: HCI dev 0 up Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: Starting security manager 0 Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: ioctl(HCIUNBLOCKADDR): Invalid argument (22) Mar 11 22:13:00 tacone-macbook kernel: [ 158.818600] Bluetooth: RFCOMM TTY layer initialized Mar 11 22:13:00 tacone-macbook kernel: [ 158.818607] Bluetooth: RFCOMM socket layer initialized Mar 11 22:13:00 tacone-macbook kernel: [ 158.818610] Bluetooth: RFCOMM ver 1.11 Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: probe failed with driver input-headset for device /org/bluez/2242/hci0/dev_F8_DB_7F_AF_6B_EE Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: Adapter /org/bluez/2242/hci0 has been enabled Mar 11 22:13:00 tacone-macbook pulseaudio[1757]: bluetooth-util.c: Error from ListDevices reply: org.freedesktop.DBus.Error.AccessDenied Mar 11 22:13:00 tacone-macbook NetworkManager[1247]: <warn> bluez error getting adapter properties: Rejected send message, 1 matched rules; type="method_call", sender=":1.4" (uid=0 pid=1247 comm="NetworkManager) interface="org.bluez.Adapter" member="GetProperties" error name="(unset)" requested_reply=0 destination="org.bluez" (uid=0 pid=2242 comm="/usr/sbin/bluetoothd)) Mar 11 22:13:00 tacone-macbook bluetoothd[2243]: return_link_keys (sba=00:23:6C:B5:03:6F, dba=00:23:6C:C0:F1:B0) Mar 11 22:13:00 tacone-macbook pulseaudio[1757]: bluetooth-util.c: Error from GetProperties reply: org.freedesktop.DBus.Error.AccessDenied Mar 11 22:15:02 tacone-macbook bluetoothd[2243]: Discovery session 0x2262d7c0 with :1.45 activated Mar 11 22:15:15 tacone-macbook bluetoothd[2243]: Stopping discovery Mar 11 22:15:15 tacone-macbook pulseaudio[1757]: bluetooth-util.c: Error from GetProperties reply: org.freedesktop.DBus.Error.AccessDenied Mar 11 22:15:16 tacone-macbook bluetoothd[2243]: link_key_request (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE) Mar 11 22:15:16 tacone-macbook bluetoothd[2243]: io_capa_request (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE) Mar 11 22:15:17 tacone-macbook bluetoothd[2243]: io_capa_response (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE) Mar 11 22:15:18 tacone-macbook bluetoothd[2243]: Stopping discovery Mar 11 22:15:28 tacone-macbook bluetoothd[2243]: link_key_notify (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE, type=5) Mar 11 22:15:28 tacone-macbook kernel: [ 306.585725] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:15:28 tacone-macbook kernel: [ 306.630757] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:15:28 tacone-macbook bluetoothd[2243]: Authentication requested Mar 11 22:15:28 tacone-macbook bluetoothd[2243]: link_key_request (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE) Mar 11 22:15:28 tacone-macbook kernel: [ 306.784829] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:15:28 tacone-macbook kernel: [ 306.857861] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:15:29 tacone-macbook bluetoothd[2243]: probe failed with driver input-headset for device /org/bluez/2242/hci0/dev_F8_DB_7F_AF_6B_EE Mar 11 22:15:29 tacone-macbook pulseaudio[1757]: bluetooth-util.c: Error from GetProperties reply: org.freedesktop.DBus.Error.AccessDenied Mar 11 22:15:29 tacone-macbook pulseaudio[1757]: last message repeated 8 times Mar 11 22:15:29 tacone-macbook bluetoothd[2243]: Stopping discovery Mar 11 22:15:30 tacone-macbook modem-manager: (tty/rfcomm0): could not get port's parent device Mar 11 22:15:30 tacone-macbook modem-manager: (rfcomm0) opening serial device... Mar 11 22:15:30 tacone-macbook modem-manager: (rfcomm0): probe requested by plugin 'Generic' Mar 11 22:15:43 tacone-macbook modem-manager: (rfcomm0) closing serial device... Mar 11 22:15:43 tacone-macbook modem-manager: (rfcomm0) opening serial device... Mar 11 22:15:49 tacone-macbook modem-manager: (rfcomm0) closing serial device... Mar 11 22:16:15 tacone-macbook modem-manager: (tty/rfcomm0): could not get port's parent device Mar 11 22:16:19 tacone-macbook kernel: [ 357.375108] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:16:24 tacone-macbook bluetoothd[2243]: link_key_request (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE) Mar 11 22:16:24 tacone-macbook kernel: [ 362.169506] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:16:24 tacone-macbook kernel: [ 362.215529] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:16:24 tacone-macbook bluetoothd[2243]: link_key_request (sba=00:23:6C:B5:03:6F, dba=F8:DB:7F:AF:6B:EE) Mar 11 22:16:24 tacone-macbook kernel: [ 362.281559] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:16:24 tacone-macbook kernel: [ 362.330588] l2cap_recv_acldata: Unexpected continuation frame (len 0) Mar 11 22:16:24 tacone-macbook modem-manager: (tty/rfcomm0): could not get port's parent device Any help ? PS: tethering via USB or WiFi is not an option, I need to do it over Bluetooth.

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  • Guest Post: Christian Finn: Is Facebook About to Become a Victim of its Own Success?

    - by Michael Snow
    12.00 Print 0 false false false EN-US X-NONE X-NONE /* 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:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Cambria","serif"; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Cambria; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;}  Since we have a number of new members of the WebCenter Evangelist team - I thought it would be appropriate to close the week with the newest hire and leader of the global WebCenter Evangelists, Christian Finn, who has just joined the Red team after many years with the small technology company up in Redmond, WA. He gave an intro to himself in an earlier post this morning but his post below is a great example of how customer engagement takes on a life of its own in our global online connected and social digital ecosystem. Is Facebook About to Become a Victim of its Own Success? What if I told you that your brand could advertise so successfully, you wouldn’t have to pay for the ads? A recent campaign by Ford Motor Company for the Ford Focus featuring Doug the spokespuppet (I am not making this up) did just that—and it raises some interesting issues for marketers and social media alike in the brave new world of customer engagement that is the Social Web. Allow me to elaborate. An article in the Wall Street Journal last week—“Big Brands Like Facebook, But They Don’t Like to Pay” tells the story of Ford’s recently concluded online campaign for the 2012 Ford Focus. (Ford, by the way, under the leadership of people such as Scott Monty, has been a pioneer of effective social campaigns.) The centerpiece of the campaign was the aforementioned Doug, who appeared as a character on Facebook in videos and via chat. (If you are not familiar with Doug, you can see him in action here, and read the WSJ story here.) You may be thinking puppet ads are a sign of Internet Bubble 2.0 and want to stop now, but bear with me. The Journal reported that Ford spent about $95M on its overall Ford Focus campaign, with TV accounting for over $60M of that spend. The Internet buy for the campaign was just over $10M, which included ad buys to drive traffic to Facebook for people to meet and ‘Like’ Doug and some amount on Facebook ads, too, to promote Doug and by extension, the Ford Focus. So far, a fairly straightforward consumer marketing story in the Internet Era. Yet here’s the curious thing: once Doug reached 10,000 fans on Facebook, Ford stopped paying for Facebook ads. Doug had gone viral with people sharing his videos with one another; once critical mass was reached there was no need to buy more ads on Facebook. Doug went on to be Liked by over 43,000 people, and 61% of his fans said they would be more likely to consider buying a Focus. According to the article, Ford says Focus sales are up this year—and increasing sales is every marketer’s goal. And so in effect, Ford found its Facebook campaign so successful that it could stop paying for it, instead letting its target consumers communicate its messages for fun—and for free. Not only did they get a 3X increase in fans beyond their paid campaign, they had thousands of customers sharing their messages in video form for months. Since free advertising is the Holy Grail of marketing both old and new-- and it appears social networks have an advantage in generating that buzz—it seems reasonable to ask: what would happen to brands’ advertising strategies—and the media they use to engage customers, if this success were repeated at scale? It seems logical to conclude that, at least initially, more ad dollars would be spent with social networks like Facebook as brands attempt to replicate Ford’s success. Certainly Facebook ad revenues are on the rise—eMarketer expects Facebook’s ad revenues to quintuple by 2012 compared with 2009 levels, to nearly 2.9B. That’s bad news for TV and the already battered print media and good news for Facebook. But perhaps not so over the longer run. With TV buys, you have to keep paying to generate impressions. If Doug the spokespuppet is any guide, however, that may not be true for social media campaigns. After an initial outlay, if a social campaign takes off, the audience will generate more impressions on its own. Thus a social medium like Facebook could be the victim of its own success when it comes to ad revenue. It may be there is an inherent limiting factor in the ad spend they can capture, as exemplified by Ford’s experience with Dough and the Focus. And brands may spend much less overall on advertising, with as good or better results, than they ever have in the past. How will these trends evolve? Can brands create social campaigns that repeat Ford’s formula for the Focus with effective results? Can social networks find ways to capture more spend and overcome their potential tendency to make further spend unnecessary? And will consumers become tired and insulated from social campaigns, much as they have to traditional advertising channels? These are the questions CMOs and Facebook execs alike will be asking themselves in the brave new world of customer engagement. As always, your thoughts and comments are most welcome.

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  • Handling Trailing Delimiters in HL7 Messages

    - by Thomas Canter
    Applies to: BizTalk Server 2006 with the HL7 1.3 Accelerator Outline of the problem Trailing Delimiters are empty values at the end of an object in a HL7 ER7 formatted message. Examples: Empty Field NTE|P| NTE|P|| Empty component ORC|1|725^ Empty Subcomponent ORC|1|||||27& Empty repeat OBR|1||||||||027~ Trailing delimiters indicate the following object exists and is empty, which is quite different from null, null is an explicit value indicated by a pair of double quotes -> "". The BizTalk HL7 Accelerator by default does not allow trailing delimiters. There are three methods to allow trailing delimiters. NOTE: All Schemas always allow trailing delimiters in the MSH Segment Using party identifiers MSH3.1 – Receive/inbound processing, using this value as a party allows you to configure the system to allow inbound trailing delimiters. MSH5.1 – Send/outbound processing, using this value as a party allows you to configure the system to allow outbound trailing delimiters. Generally, if you allow inbound trailing delimiters, unless you are willing to programmatically remove all trailing delimiters, then you need to configure the send to allow trailing delimiters. Add the appropriate parties to the BizTalk Parties list from these two fields in your message stream. Open the BizTalk HL7 Configuration tool and for each party check the "Allow trailing delimiters (separators)" check box on the Validation tab. Disadvantage – Each MSH3.1 and MSH5.1 value must be represented in the parties list and configured. Advantage – granular control over system behavior for each inbound/outbound system. Using instance properties of a pipeline used in a send port or receive location. Open the BizTalk Server Administration console locate the send port or receive location that contains the BTAHL72XReceivePipeline or BTAHL72XSendPipeline pipeline. Open the properties To the right of the pipeline selected locate the […] ellipses button In the property list, locate the "TrailingDelimiterAllowed" property and set it to True. Advantage – All messages through a particular Send Port or Receive Location will allow trailing delimiters. Disadvantage – Must configure each Send Port or Receive Location. No granular control over which remote parties will send or receive messages with trailing delimiters. Using a custom pipeline that uses a pre-configured BTA HL7 Pipeline component. Use Visual Studio to construct a custom receive and send pipeline using the appropriate assembler or dissasembler. Set the component property to "TrailingDelimitersAllowed" to True Compile and deploy the custom pipeline Use the custom pipeline instead of the standard pipeline for all HL7 message processing Advantage – All messages using the custom pipeline will automatically allow trailing delimiters. Disadvantage – Requires custom coding and development to create and deploy the custom pipeline. No granular control over which remote parties will send or receive messages with trailing delimiters. What does a Trailing Delimiter do to the XML Schema? Allowing trailing delimiters does not have the impact often expected in the actual XML Schema.The Schema reproduces the message with no data loss.Thus, the message when represented in XML must contain the extra fields, in order to reproduce the outbound message.Thus, a trialing delimiter results in an empty XML field.Trailing Delmiters are not stripped from the inbound message. Example:<PID_21>44172</PID_21><PID_21>9257</PID_21> -> the original maximum number of repeats<PID_21></PID_21> -> The empty repeated field Allowing trailing delimiters not remove the trailing delimiters from the message, it simply suppresses the check that will cause the message to fail parse with trailing delimiters. When can you not fix the problem by enabling trailing delimiters Each object in a message must have a location in the target BTAHL7 schema for its content to reside.If you have more objects in the message than are contained at that location, then enabling trailing delimiters will not resolve the problem. The schema must be extended to accommodate the empty message content.Examples: Extra Field NTE|P||||Only 4 fields in NTE Segment, the 4th field exists, but is empty. Extra component PID|1|1523|47^^^^^^^Only 5 components in a CX data type, the 5th component exists, but is empty Extra subcomponent ORC|1|||||27&&Only 2 subcomponents in a CQ data type, the 3rd subcomponent is empty, but exists. Extra Repeat PID|1||||||||||||||||||||4419~5217~Only 2 repeats allowed for the field "Mother's identifier", the repeat is empty, but exists. In each of these cases, you must locate the failing object and extend the type to allow an additional object of that type. FieldAdd a field of ST to the end of the segment with a suitable name in the segments_nnn.xsd Component Create a new Custom CX data type (i.e. CX_XtraComp) in the datatypes_nnn.xsd and add a new component to the custom CX data type. Update the field in the segments_nnn.xsd file to use the custom data type instead of the standard datatype. Subcomponent Create a new Custom CQ data type that accepts an additional TS value at the end of the data type. Create a custom TQ data type that uses the new custom CQ data type as the first subcomponent. Modify the ORC segment to use the new CQ data type at ORC.7 instead of the standard CQ data type. RepeatModify the Field definition for PID.21 in the segments_nnn.xsd to allow more repeats in the field.

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  • Connection Pooling is Busted

    - by MightyZot
    A few weeks ago we started getting complaints about performance in an application that has performed very well for many years.  The application is a n-tier application that uses ADODB with the SQLOLEDB provider to talk to a SQL Server database.  Our object model is written in such a way that each public method validates security before performing requested actions, so there is a significant number of queries executed to get information about file cabinets, retrieve images, create workflows, etc.  (PaperWise is a document management and workflow system.)  A common factor for these customers is that they have remote offices connected via MPLS networks. Naturally, the first thing we looked at was the query performance in SQL Profiler.  All of the queries were executing within expected timeframes, most of them were so fast that the duration in SQL Profiler was zero.  After getting nowhere with SQL Profiler, the situation was escalated to me.  I decided to take a peek with Process Monitor.  Procmon revealed some “gaps” in the TCP/IP traffic.  There were notable delays between send and receive pairs.  The send and receive pairs themselves were quite snappy, but quite often there was a notable delay between a receive and the next send.  You might expect some delay because, presumably, the application is doing some thinking in-between the pairs.  But, comparing the procmon data at the remote locations with the procmon data for workstations on the local network showed that the remote workstations were significantly delayed.  Procmon also showed a high number of disconnects. Wireshark traces showed that connections to the database were taking between 75ms and 150ms.  Not only that, but connections to a file share containing images were taking 2 seconds!  So, I asked about a trust.  Sure enough there was a trust between two domains and the file share was on the second domain.  Joining a remote workstation to the domain hosting the share containing images alleviated the time delay in accessing the file share.  Removing the trust had no affect on the connections to the database. Microsoft Network Monitor includes filters that parse TDS packets.  TDS is the protocol that SQL Server uses to communicate.  There is a certificate exchange and some SSL that occurs during authentication.  All of this was evident in the network traffic.  After staring at the network traffic for a while, and examining packets, I decided to call it a night.  On the way home that night, something about the traffic kept nagging at me.  Then it dawned on me…at the beginning of the dance of packets between the client and the server all was well.  Connection pooling was working and I could see multiple queries getting executed on the same connection and ethereal port.  After a particular query, connecting to two different servers, I noticed that ADODB and SQLOLEDB started making repeated connections to the database on different ethereal ports.  SQL Server would execute a single query and respond on a port, then open a new port and execute the next query.  Connection pooling appeared to be broken. The next morning I wrote a test to confirm my hypothesis.  Turns out that the sequence causing the connection nastiness goes something like this: Make a connection to the database. Open a result set that returns enough records to require multiple roundtrips to the server. For each result, query for some other data in the database (this will open a new implicit connection.) Close the inner result set and repeat for every item in the original result set. Close the original connection. Provided that the first result set returns enough data to require multiple roundtrips to the server, ADODB and SQLOLEDB will start making new connections to the database for each query executed in the loop.  Originally, I thought this might be due to Microsoft’s denial of service (ddos) attack protection.  After turning those features off to no avail, I eventually thought to switch my queries to client-side cursors instead of server-side cursors.  Server-side cursors are the default, by the way.  Voila!  After switching to client-side cursors, the disconnects were gone and the above sequence yielded two connections as expected. While the real problem is the amount of time it takes to make connections over these MPLS networks (100ms on average), switching to client-side cursors made the problem go away.  Believe it or not, this is actually documented by Microsoft, and rather difficult to find.  (At least it was while we were trying to troubleshoot the problem!)  So, if you’re noticing performance issues on slower networks, or networks with slower switching, take a look at the traffic in a tool like Microsoft Network Monitor.  If you notice a high number of disconnects, and you’re using fire-hose or server-side cursors, then try switching to client-side cursors and you may see the problem go away. Most likely, Microsoft believes this to be appropriate behavior, because ADODB can’t guarantee that all of the data has been retrieved when you execute the inner queries.  I’m not convinced, though, because the problem remains even after replacing all of the implicit connections with explicit connections and closing those connections in-between each of the inner queries.  In that case, there doesn’t seem to be a reason why ADODB can’t use a single connection from the connection pool to make the additional queries, bringing the total number of connections to two.  Instead ADO appears to make an assumption about the state of the connection. I’ve reported the behavior to Microsoft and am awaiting to hear from the appropriate team, so that I can demonstrate the problem.  Maybe they can explain to us why this is appropriate behavior.  :)

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  • PASS Summit 2010 Recap

    - by AjarnMark
    Last week I attended my eighth PASS Summit in nine years, and every year it is a fantastic event!  I was fortunate my first year to have a contact (Bill Graziano (blog | Twitter) from SQLTeam) that I was expecting to meet, and who got me started on a good track of making new contacts.  Each year I have made a few more, and renewed friendships from years past.  Many of the attendees agree that the pure networking opportunities are one of the best benefits of attending the Summit.  And there’s a lot of great technical stuff, too, some of the things that stick out for me this year include… Pre-Con Monday: PowerShell with Allen White (blog | Twitter).  This was the first time that I attended a pre-con.  For those not familiar with the concept, the regular sessions for the conference are 75-90 minutes long.  For an extra fee, you can attend a full-day session on a single topic during a pre- or post-conference training day.  I had been meaning for several months to dive in and learn PowerShell, but just never seemed to find (or make) the time for it, so when I saw this was one of the all-day sessions, and I was planning to be there on Monday anyway, I decided to go for it.  And it was well worth it!  I definitely came out of there with a good foundation to build my own PowerShell scripts, plus several sample scripts that he showed which already cover the first four or five things I was planning to do with PowerShell anyway.  This looks like the right tool for me to build an automated version of our software deployment process, which right now contains many repeated steps.  Thanks Allen! Service Broker with Denny Cherry (blog | Twitter).  I remembered reading Denny’s blog post on Using Service Broker instead of Replication, and ever since then I have been thinking about using this to populate a new reporting-focused Data Repository that we will be building in the near future.  When I saw he was doing this session, I thought it would be great to get more information and be able to ask the author questions.  When I brought this idea back to my boss, he really liked it, as we had previously been discussing doing nightly data loads, with an option to manually trigger a mid-day load if up-to-the-minute data was needed for something.  If we go the Service Broker route, we can keep the Repository current in near real-time.  Hooray! DBA Mythbusters with Paul Randal (blog | Twitter).  Even though I read every one of the posts in Paul’s blog series of the same name, I had to go see the legend in person.  It was great, and I still learned something new! How to Conduct Effective Meetings with Joe Webb (blog | Twitter).  I always like to sit in on a session that Joe does.  I met Joe several years ago when both he and Bill Graziano were on the PASS Board of Directors together, and we have kept in touch.  Joe is very well-spoken and has great experience with both SQL Server and business.  And we could certainly use some pointers at my work (probably yours, too) on making our meetings more effective and to run on-time.  Of course, now that I’m the Chapter Leader for the Professional Development virtual chapter, I also had to sit in on this ProfDev session and recruit Joe to do a presentation or two for the chapter next year. Query Optimization with David DeWitt.  Anyone who has seen Dr. David DeWitt present the 3rd keynote at a PASS Summit over the last three years knows what a great time it is to sit and listen to him make some really complicated and advanced topic easy to understand (although it still makes your head hurt).  It still amazes me that the simple two-table join query from pubs that he used in his example can possibly have 22 million possible physical query plans.  Ouch! Exhibit Hall:  This year I spent more serious time in the exhibit hall than any year past.  I have talked my boss into making a significant (for us) investment in monitoring tools next year, and this was a great opportunity to talk with all the big-hitters.  Readers of mine may recall that I fell in love with the SQL Sentry Power Suite several months ago and wrote a blog entry about it just from the trial version.  Well as things turned out, short-term budget priorities shifted, and we weren’t able to make the purchase then.  I have it in the budget for next year, but since I was going to the Summit, my boss wanted me to look at the other options to see if this was really the one that we wanted.  I spent a couple of hours talking with representatives from Red-Gate, Idera, Confio, and Quest about their offerings, and giving them each the same 3 scenarios that I wanted to be able to accomplish based on the questions and issues that arise in our company.  It was interesting to discover the different approaches or “world view” that each vendor takes to the subject of performance monitoring and troubleshooting.  I may write a separate article that goes into this in more depth, but the product that best aligned with our point of view, and met the current needs we have is still the SQL Sentry Power Suite.  I’m not saying that the others are bad or wrong or anything like that, just that the way they tackled the issue did not align as well with our particular needs as does SQL Sentry’s product.  And that was something I learned too, when you go shopping for these products, you really need to know what you want to get from them.  It’s best if you have a few example scenarios from work that you can use to test out how well each tool fits your particular needs. Overall, another GREAT event.  I can’t wait to get the DVDs so I can sit in on a bunch of other sessions that I couldn’t get to because I was in one of the ones above.  And I can hardly wait until next year!

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  • OpenWorld: Spotlight on Fusion CRM

    - by Tony Berk
    Oracle OpenWorld is less than 2 weeks away, so you need to start figuring out how you are going to maximize your week. I don't want to discourage you, but I'm pretty sure it is impossible to attend all 2000+ sessions. So you need to focus on what's important to you. Many of our CRM customers will be interested in Fusion CRM, since they have already started Fusion implementations or determining when to start. If that's you, or you are just looking for an overview of Fusion CRM, we've got you covered! Let's start at the top! For an overview of what is in Fusion CRM and where it is going, you should attend the general session and roadmap session: General Session: Oracle Fusion CRM—Improving Sales Effectiveness, Efficiency, and Ease of Use (Session ID: GEN9674) - Oct 2, 11:45 AM. Anthony Lye, Senior VP, Oracle leads this general session focused on Oracle Fusion CRM. Oracle Fusion CRM optimizes territories, combines quota management and incentive compensation, integrates sales and marketing, and cleanses and enriches data—all within a single application platform. Oracle Fusion can be configured, changed, and extended at runtime by end users, business managers, IT, and developers. Oracle Fusion CRM can be used from the Web, from a smartphone, from Microsoft Outlook, or from an iPad. Deloitte, sponsor of the CRM Track, will also present key concepts on CRM implementations. Oracle Fusion Customer Relationship Management: Overview/Strategy/Customer Experiences/Roadmap (CON9407) - Oct 1, 3:15PM. In this session, learn how Oracle Fusion CRM enables companies to create better sales plans, generate more quality leads, and achieve higher win rates and find out why customers are adopting Oracle Fusion CRM. Gain a deeper understanding of the unique capabilities only Oracle Fusion CRM provides, and learn how Oracle’s commitment to CRM innovation is driving a wide range of future enhancements. There is also a General Session for all Fusion Applications providing insight into the current strategy of the full product line and a high-level roadmap for each product area: Oracle Fusion Applications—Overview, Strategy, and Roadmap (GEN9433) - Oct 1, 10:45AM. This session will be repeated on Oct 3, 10:15AM. Now, if you want to drill down into some more detail, there are a lot more sessions with Oracle product management and customers. I'll highlight a few, but suggest you review the Fusion CRM Focus On document, or the search in the Content Catalog or Session Builder.  Driving Sales Performance with Oracle Fusion CRM (CON9744) - Oct 3, 10:15AM. Demonstrates how sales executives can gain instant visibility into their business, deliver pervasive coaching to their reps, maximize their sales pipeline, and drive team alignment. The result is increased sales performance that enables sales executives to deliver more revenue without increasing their resources or expenses. Maximize Your Revenue Potential with Oracle Fusion CRM Sales Planning (CON9751) - Oct 2, 1:15PM. Learn how Oracle Fusion CRM helps companies intelligently optimize sales planning and manage sales performance including the ability to predict their future sales opportunities and use those predictions in conjunction with past sales data to optimally define their sales territories, sales quotas, and incentive compensation plans. Boost Marketing’s Contribution to Revenue with Oracle Fusion CRM Marketing (CON9746) - Oct 3, 11:45AM. Learn how Oracle Fusion CRM can help your organization integrate sales and marketing, using one CRM platform. See how Oracle Fusion CRM can help your organization learn where to invest its precious marketing dollars; drive more revenue with cross-channel marketing and prospecting capabilities, including and not limited to e-mail, Web, and social media; improve lead conversion with integrated lead management functionality; and do more with less by automating many manual tasks. Oracle Fusion CRM: Social Marketing (CON11559) - Oct 1, 3:15PM. Learn how Oracle’s acquisition of Collective Intellect, Vitrue, and Involver extends Oracle Fusion Marketing as a world-class social marketing solution. Oracle Fusion Social CRM Strategy and Roadmap: Future of Collaboration and Social Engagement (CON9750) - Oct 4, 11:15AM. Hear how Oracle can help you know your customers better, encourage brand affinity, and improve collaboration within your ecosystem. This session reviews Oracle's social media solution and shows how you can discover hidden insights buried in your enterprise and social data. Also learn how Oracle Social Network revolutionizes how enterprise users work, collaborate, and share to achieve successful outcomes. Of course, we recommend you hear from the current Fusion CRM customers too. So, don't miss Oracle Fusion Customer Relationship Management: Customer Adoption and Experiences (CON9415) on Oct 3 at 10:15AM for panel of customers discussing implementation experiences, best practices and benefits.  After listening to all of this great information, you are probably going to have questions. Well, the experts will be on hand to help answer your questions and plan how your organization can get going with Fusion CRM. Be sure to head down to the DEMOgrounds and CRM Pavilion in the Moscone West Exhibit Hall. And finally, there is the always popular Meet the Experts session focused on Fusion CRM (MTE9658) on Oct 2 at 5PM (pre-registration via Schedule Builder is recommended.) In addition, there are more sessions on Mobility, Extensibility, Incentive Compensation, Fusion Customer Hub and other key components of the Fusion Applications infrastructure, Oracle Cloud and much, much more! For a full list, utilize the Fusion CRM Focus On document and Content Catalog. Enjoy!

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  • Why is my external USB hard drive sometimes completely inaccessible?

    - by Eliah Kagan
    I have an external USB hard drive, consisting of an 1 TB SATA drive in a Rosewill RX35-AT-SU SLV Aluminum 3.5" Silver USB 2.0 External Enclosure, plugged into my SONY VAIO VGN-NS310F laptop. It is plugged directly into the computer (not through a hub). The drive inside the enclosure is a 7200 rpm Western Digital, but I don't remember the exact model. I can remove the drive from the enclosure (again), if people think it's necessary to know that detail. The drive is formatted ext4. I mount it dynamically with udisks on my Lubuntu 11.10 system, usually automatically via PCManFM. (I have had Lubuntu 12.04 on this machine, and experienced all this same behavior with that too.) Every once in a while--once or twice a day--it becomes inaccessible, and difficult to unmount. Attempting to unmount it with sudo umount ... gives an error message saying the drive is in use and suggesting fuser and lsof to find out what is using it. Killing processes found to be using the drive with fuser and lsof is sometimes sufficient to let me unmount it, but usually isn't. Once the drive is unmounted or the machine is rebooted, the drive will not mount. Plugging in the drive and turning it on registers nothing on the computer. dmesg is unchanged. The drive's access light usually blinks vigorously, as though the drive is being accessed constantly. Then eventually, after I keep the drive off for a while (half an hour), I am able to mount it again. While the drive doesn't work on this machine for a while, it will work immediately on another machine running the same version of Ubuntu. Sometimes bringing it back over from the other machine seems to "fix" it. Sometimes it doesn't. The drive doesn't always stop being accessible while mounted, before becoming unmountable. Sometimes it works fine, I turn off the computer, I turn the computer back on, and I cannot mount the drive. Currently this is the only drive with which I have this problem, but I've had problems that I think are the same as this, with different drives, on different Ubuntu machines. This laptop has another external USB drive plugged into it regularly, which doesn't have this problem. Unplugging that drive before plugging in the "problem" drive doesn't fix the problem. I've opened the drive up and made sure the connections were tight in the past, and that didn't seem to help (any more than waiting the same amount of time that it took to open and close the drive, before attempting to remount it). Does anyone have any ideas about what could be causing this, what troubleshooting steps I should perform, and/or how I could fix this problem altogether? Update: I tried replacing the USB data cable (from the enclosure to the laptop), as Merlin suggested. I should've tried that long ago, since it fits the symptoms perfectly (the drive works on another machine, which would make sense because the cable would be bent at a different angle, possibly completing a circuit of frayed wires). Unfortunately, though, this did not help--I have the same problem with the new cable. I'll try to provide additional detailed information about the drive inside the enclosure, next time I'm able to get the drive working. (At the moment I don't have another machine available to attach it.) Major Update (28 June 2012) The drive seems to have deteriorated considerably. I think this is so, because I've attached it to another machine and gotten lots of errors about invalid characters, when copying files from it. I am less interested in recovering data from the drive than I am in figuring out what is wrong with it. I specifically want to figure out if the problem is the drive or the enclosure. Now, when I plug the drive into the original machine where I was having the problems, it still doesn't appear (including with sudo fdisk -l), but it is recognized by the kernel and messages are added to dmesg. Most of the message consist of errors like this, repeated many times: [ 7.707593] sd 5:0:0:0: [sdc] Unhandled sense code [ 7.707599] sd 5:0:0:0: [sdc] Result: hostbyte=invalid driverbyte=DRIVER_SENSE [ 7.707606] sd 5:0:0:0: [sdc] Sense Key : Medium Error [current] [ 7.707614] sd 5:0:0:0: [sdc] Add. Sense: Unrecovered read error [ 7.707621] sd 5:0:0:0: [sdc] CDB: Read(10): 28 00 00 00 00 00 00 00 08 00 [ 7.707636] end_request: critical target error, dev sdc, sector 0 [ 7.707641] Buffer I/O error on device sdc, logical block 0 Here are all the lines from dmesg starting with when the drive is recognized. Please note that: I'm back to running Lubuntu 12.04 on this machine (and perhaps that's a factor in better error messages). Now that the drive has been plugged into another machine and back into this one, and also now that this machine is back to running 12.04, the drive's access light doesn't blink as I had described. Looking at the drive, it would appear as though it is working normally, with low or no access. This behavior (the errors) occurs when rebooting the machine with the drive plugged in, and also when manually plugging in the drive. A few of the messages are about /dev/sdb. That drive is working fine. The bad drive is /dev/sdc. I just didn't want to edit anything out from the middle.

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  • The illusion of Competence

    - by tony_lombardo
    Working as a contractor opened my eyes to the developer food chain.  Even though I had similar experiences earlier in my career, the challenges seemed much more vivid this time through.  I thought I’d share a couple of experiences with you, and the lessons that can be taken from them. Lesson 1: Beware of the “funnel” guy.  The funnel guy is the one who wants you to funnel all thoughts, ideas and code changes through him.  He may say it’s because he wants to avoid conflicts in source control, but the real reason is likely that he wants to hide your contributions.  Here’s an example.  When I finally got access to the code on one of my projects, I was told by the developer that I had to funnel all of my changes through him.  There were 4 of us coding on the project, but only 2 of us working on the UI.  The other 2 were working on a separate application, but part of the overall project.  So I figured, I’ll check it into SVN, he reviews and accepts then merges in.  Not even close.  I didn’t even have checkin rights to SVN, I had to email my changes to the developer so he could check those changes in.  Lesson 2: If you point out flaws in code to someone supposedly ‘higher’ than you in the developer chain, they’re going to get defensive.  My first task on this project was to review the code, familiarize myself with it.  So of course, that’s what I did.  And in familiarizing myself with it, I saw so many bad practices and code smells that I immediately started coming up with solutions to fix it.  Of course, when I reviewed these changes with the developer (guy who originally wrote the code), he smiled and nodded and said, we can’t make those changes now, it’s too destabilizing.  I recommended we create a new branch and start working on refactoring, but branching was a new concept for this guy and he was worried we would somehow break SVN. How about some concrete examples? I started out by recommending we remove NUnit dependency and tests from the application project, and create a separate Unit testing project.  This was met with a little bit of resistance because - “How do I access the private methods?”  As it turned out there weren’t really any private methods that weren’t exposed by public methods, so I quickly calmed this fear. Win 1 Loss 0 Next, I recommended that all of the File IO access be wrapped in Using clauses, or at least properly wrapped in try catch finally.  This recommendation was accepted.. but never implemented. Win 2  Loss 1 Next recommendation was to refactor the command pattern implementation.  The command pattern was implemented, but it wasn’t really necessary for the application.  More over, the fact that we had 100 different command classes, each with it’s own specific command parameters class, made maintenance a huge hassle.  The same code repeated over and over and over.  This recommendation was declined, the code was too fragile and this change would destabilize it.  I couldn’t disagree, though it was the commands themselves in many cases that were fragile. Win 2 Loss 2 Next recommendation was to aid performance (and responsiveness) of the application by using asynchronous service calls.  This on was accepted. Win 2 Loss 3 If you’re paying any attention, you’re wondering why the async service calls was scored as a loss.. Let me explain.  The service call was made using the async pattern.  Followed by a thread.sleep  <facepalm>. Now it’s easy to be harsh on this kind of code, especially if you’re an experienced developer.  But I understood how most of this happened.  One junior guy, working as hard as he can to build his first real world application, with little or no guidance from anyone else.  He had his pattern book and theory of programming to help him, but no real world experience.  He didn’t know how difficult it would be to trace the crashes to the coding issues above, but he will one day.  The part that amazed me was the management position that “this guy should be a team lead, because he’s worked so hard”.  I’m all for rewarding hard work, but when you reward someone by promoting them past the point of their competence, you’re setting yourself and them up for failure.  And that’s lesson 3.  Just because you’ve got a hard worker, doesn’t mean he should be leading a development project.  If you’re a junior guy busting your ass, keep at it.  I encourage you to try new things, but most importantly to learn from your mistakes.  And correct your mistakes.  And if someone else looks at your code and shows you a laundry list of things that should be done differently, don’t take it personally – they’re really trying to help you.  And if you’re a senior guy, working with a junior guy, it’s your duty to point out the flaws in the code.  Even if it does make you the bad guy.  And while I’ve used “guy” above, I mean both men and women.  And in some cases mutant dinosaurs. 

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  • Extreme Optimization – Numerical Algorithm Support

    - by JoshReuben
    Function Delegates Many calculations involve the repeated evaluation of one or more user-supplied functions eg Numerical integration. The EO MathLib provides delegate types for common function signatures and the FunctionFactory class can generate new delegates from existing ones. RealFunction delegate - takes one Double parameter – can encapsulate most of the static methods of the System.Math class, as well as the classes in the Extreme.Mathematics.SpecialFunctions namespace: var sin = new RealFunction(Math.Sin); var result = sin(1); BivariateRealFunction delegate - takes two Double parameters: var atan2 = new BivariateRealFunction (Math.Atan2); var result = atan2(1, 2); TrivariateRealFunction delegate – represents a function takes three Double arguments ParameterizedRealFunction delegate - represents a function taking one Integer and one Double argument that returns a real number. The Pow method implements such a function, but the arguments need order re-arrangement: static double Power(int exponent, double x) { return ElementaryFunctions.Pow(x, exponent); } ... var power = new ParameterizedRealFunction(Power); var result = power(6, 3.2); A ComplexFunction delegate - represents a function that takes an Extreme.Mathematics.DoubleComplex argument and also returns a complex number. MultivariateRealFunction delegate - represents a function that takes an Extreme.Mathematics.LinearAlgebra.Vector argument and returns a real number. MultivariateVectorFunction delegate - represents a function that takes a Vector argument and returns a Vector. FastMultivariateVectorFunction delegate - represents a function that takes an input Vector argument and an output Matrix argument – avoiding object construction  The FunctionFactory class RealFromBivariateRealFunction and RealFromParameterizedRealFunction helper methods - transform BivariateRealFunction or a ParameterizedRealFunction into a RealFunction delegate by fixing one of the arguments, and treating this as a new function of a single argument. var tenthPower = FunctionFactory.RealFromParameterizedRealFunction(power, 10); var result = tenthPower(x); Note: There is no direct way to do this programmatically in C# - in F# you have partial value functions where you supply a subset of the arguments (as a travelling closure) that the function expects. When you omit arguments, F# generates a new function that holds onto/remembers the arguments you passed in and "waits" for the other parameters to be supplied. let sumVals x y = x + y     let sumX = sumVals 10     // Note: no 2nd param supplied.     // sumX is a new function generated from partially applied sumVals.     // ie "sumX is a partial application of sumVals." let sum = sumX 20     // Invokes sumX, passing in expected int (parameter y from original)  val sumVals : int -> int -> int val sumX : (int -> int) val sum : int = 30 RealFunctionsToVectorFunction and RealFunctionsToFastVectorFunction helper methods - combines an array of delegates returning a real number or a vector into vector or matrix functions. The resulting vector function returns a vector whose components are the function values of the delegates in the array. var funcVector = FunctionFactory.RealFunctionsToVectorFunction(     new MultivariateRealFunction(myFunc1),     new MultivariateRealFunction(myFunc2));  The IterativeAlgorithm<T> abstract base class Iterative algorithms are common in numerical computing - a method is executed repeatedly until a certain condition is reached, approximating the result of a calculation with increasing accuracy until a certain threshold is reached. If the desired accuracy is achieved, the algorithm is said to converge. This base class is derived by many classes in the Extreme.Mathematics.EquationSolvers and Extreme.Mathematics.Optimization namespaces, as well as the ManagedIterativeAlgorithm class which contains a driver method that manages the iteration process.  The ConvergenceTest abstract base class This class is used to specify algorithm Termination , convergence and results - calculates an estimate for the error, and signals termination of the algorithm when the error is below a specified tolerance. Termination Criteria - specify the success condition as the difference between some quantity and its actual value is within a certain tolerance – 2 ways: absolute error - difference between the result and the actual value. relative error is the difference between the result and the actual value relative to the size of the result. Tolerance property - specify trade-off between accuracy and execution time. The lower the tolerance, the longer it will take for the algorithm to obtain a result within that tolerance. Most algorithms in the EO NumLib have a default value of MachineConstants.SqrtEpsilon - gives slightly less than 8 digits of accuracy. ConvergenceCriterion property - specify under what condition the algorithm is assumed to converge. Using the ConvergenceCriterion enum: WithinAbsoluteTolerance / WithinRelativeTolerance / WithinAnyTolerance / NumberOfIterations Active property - selectively ignore certain convergence tests Error property - returns the estimated error after a run MaxIterations / MaxEvaluations properties - Other Termination Criteria - If the algorithm cannot achieve the desired accuracy, the algorithm still has to end – according to an absolute boundary. Status property - indicates how the algorithm terminated - the AlgorithmStatus enum values:NoResult / Busy / Converged (ended normally - The desired accuracy has been achieved) / IterationLimitExceeded / EvaluationLimitExceeded / RoundOffError / BadFunction / Divergent / ConvergedToFalseSolution. After the iteration terminates, the Status should be inspected to verify that the algorithm terminated normally. Alternatively, you can set the ThrowExceptionOnFailure to true. Result property - returns the result of the algorithm. This property contains the best available estimate, even if the desired accuracy was not obtained. IterationsNeeded / EvaluationsNeeded properties - returns the number of iterations required to obtain the result, number of function evaluations.  Concrete Types of Convergence Test classes SimpleConvergenceTest class - test if a value is close to zero or very small compared to another value. VectorConvergenceTest class - test convergence of vectors. This class has two additional properties. The Norm property specifies which norm is to be used when calculating the size of the vector - the VectorConvergenceNorm enum values: EuclidianNorm / Maximum / SumOfAbsoluteValues. The ErrorMeasure property specifies how the error is to be measured – VectorConvergenceErrorMeasure enum values: Norm / Componentwise ConvergenceTestCollection class - represent a combination of tests. The Quantifier property is a ConvergenceTestQuantifier enum that specifies how the tests in the collection are to be combined: Any / All  The AlgorithmHelper Class inherits from IterativeAlgorithm<T> and exposes two methods for convergence testing. IsValueWithinTolerance<T> method - determines whether a value is close to another value to within an algorithm's requested tolerance. IsIntervalWithinTolerance<T> method - determines whether an interval is within an algorithm's requested tolerance.

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