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  • Are there too many qualified software development engineers chasing too few jobs?

    - by T Gregory
    I am trying to write this question in a non-argumentative way, but it is quite emotionally charged for some, so please bear with me. In the U.S., we hear constantly from CEOs that they cannot find enough qualified software engineers. In fact, it is the position of the U.S. government that demand for software engineering talent outpaces supply. This position can be clearly seen in the granting of tens of thousands of H1B visas, but also in the following excerpt from the official 2010-11 Bureau of Labor Statistics Occupational Outlook Handbook: Employment of computer software engineers is expected to increase by 32 percent from 2008-2018, which is much faster than the average for all occupations. In addition, this occupation will see a large number of new jobs, with more than 295,000 created between 2008 and 2018. Demand for computer software engineers will increase as computer networking continues to grow. For example, expanding Internet technologies have spurred demand for computer software engineers who can develop Internet, intranet, and World Wide Web applications. Likewise, electronic data-processing systems in business, telecommunications, healthcare, government, and other settings continue to become more sophisticated and complex. Implementing, safeguarding, and updating computer systems and resolving problems will fuel the demand for growing numbers of systems software engineers. New growth areas will also continue to arise from rapidly evolving technologies. The increasing uses of the Internet, the proliferation of Web sites, and mobile technology such as the wireless Internet have created a demand for a wide variety of new products. As more software is offered over the Internet, and as businesses demand customized software to meet their specific needs, applications and systems software engineers will be needed in greater numbers. In addition, the growing use of handheld computers will create demand for new mobile applications and software systems. As these devices become a larger part of the business environment, it will be necessary to integrate current computer systems with this new, more mobile technology. However, from the the employee side of the equation, we often hear the opposite. Many of the stories of SDEs with graduate degrees and decades of experience on the unemployment line, or the big tech interview war stories, are anecdotal, for sure. But, there is one piece of data that is neither anecdotal nor transitory, and that is the aggregate decisions of millions of undergraduates of what degree to pursue. Here, a different picture emerges from the data, and that picture is not good for the software profession. According the most recent Taulbee Survey from Computer Research Association, undergrad degree production in CS and CE has fallen nearly 60% since 2004. (Undergrad enrollments have ticked up in the past two years, but only modestly). Here we see that a basic disconnect between what corporate CEOs and the US government are saying and what potential employees really think about job prospects in software engineering. So my questions are these. Who are we to believe? Is there an acute talent shortage, or is there a long-term structural oversupply in the SDE labor market? Can anyone provide reliable data on long-term unemployment among SDEs? How many are leaving the profession due to lack of work? Real data is most helpful. Thanks.

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  • Using Teleriks new LINQ implementation to connect to MySQL

    Last week Telerik released a new LINQ implementation that is simple to use and produces domain models very fast. Built on top of the enterprise grade OpenAccess ORM, you can connect to any database that OpenAccess can connect to such as: SQL Server, MySQL, Oracle, SQL Azure, VistaDB, etc. Today I will show you how to build a domain model using MySQL as your back end. To get started, you have to download MySQL 5.x and the MySQL Workbench and also, as my colleague Alexander Filipov at Telerik reminded me, make sure you install the MySQL .NET Connector, which is available here.  I like to use Northwind, ok it gives me the warm and fuzzies, so I ran a script to produce Northwind on my MySQL server. There are many ways you can get Northwind on your MySQL database, here is a helpful blog to get your started. I also manipulated the first record to indicate that I am in MySQL and gave a look via the MySQL Workbench. Ok, time to build our model! Start up the Domain Model wizard by right clicking on the project in Visual Studio (I have a Web project) and select Add|New Item and choose Telerik OpenAccess Domain Model from the new item list. When the wizard comes up, choose MySQL as your back end and enter in the name of your saved MySQL connection. If you dont have a saved MySQL connection set up in Visual Studio, click on New Connection and enter in the proper connection information. *Note, this is where you need to have the MySQL .NET connector installed. After you set your connection to the MySQL database server, you have to choose which tables to include in your model. Just for fun, I will choose all of them. Give your model a name, like NorthwindEntities and click finish. That is it. Now lets consume the model with ASP .net. I created a simple page that also has a GridView on it. On my page load I wrote this code, by now it should look very familiar, a simple LINQ query filtering customers by country (Germany) and binding the results to the grid.  1: protected void Page_Load(object sender, EventArgs e) 2: { 3: if (!IsPostBack) 4: { 5: //a reference to the data context 6: NorthwindEntities dat = new NorthwindEntities(); 7: //LINQ Statement 8: var result = from c in dat.Customers 9: where c.Country == "Germany" 10: select c; 11: //Databinding to the Gridview 12: GridView1.DataSource = result; 13: GridView1.DataBind(); 14: } 15: } .csharpcode, .csharpcode pre{ font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/}.csharpcode pre { margin: 0em; }.csharpcode .rem { color: #008000; }.csharpcode .kwrd { color: #0000ff; }.csharpcode .str { color: #006080; }.csharpcode .op { color: #0000c0; }.csharpcode .preproc { color: #cc6633; }.csharpcode .asp { background-color: #ffff00; }.csharpcode .html { color: #800000; }.csharpcode .attr { color: #ff0000; }.csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em;}.csharpcode .lnum { color: #606060; } F5 produces the following. Tomorrow Ill show how to take the same model and create an Astoria/OData data feed. Technorati Tags: MySQL Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Standards Corner: Preventing Pervasive Monitoring

    - by independentid
     Phil Hunt is an active member of multiple industry standards groups and committees and has spearheaded discussions, creation and ratifications of industry standards including the Kantara Identity Governance Framework, among others. Being an active voice in the industry standards development world, we have invited him to share his discussions, thoughts, news & updates, and discuss use cases, implementation success stories (and even failures) around industry standards on this monthly column. Author: Phil Hunt On Wednesday night, I watched NBC’s interview of Edward Snowden. The past year has been tumultuous one in the IT security industry. There has been some amazing revelations about the activities of governments around the world; and, we have had several instances of major security bugs in key security libraries: Apple's ‘gotofail’ bug  the OpenSSL Heartbleed bug, not to mention Java’s zero day bug, and others. Snowden’s information showed the IT industry has been underestimating the need for security, and highlighted a general trend of lax use of TLS and poorly implemented security on the Internet. This did not go unnoticed in the standards community and in particular the IETF. Last November, the IETF (Internet Engineering Task Force) met in Vancouver Canada, where the issue of “Internet Hardening” was discussed in a plenary session. Presentations were given by Bruce Schneier, Brian Carpenter,  and Stephen Farrell describing the problem, the work done so far, and potential IETF activities to address the problem pervasive monitoring. At the end of the presentation, the IETF called for consensus on the issue. If you know engineers, you know that it takes a while for a large group to arrive at a consensus and this group numbered approximately 3000. When asked if the IETF should respond to pervasive surveillance attacks? There was an overwhelming response for ‘Yes'. When it came to 'No', the room echoed in silence. This was just the first of several consensus questions that were each overwhelmingly in favour of response. This is the equivalent of a unanimous opinion for the IETF. Since the meeting, the IETF has followed through with the recent publication of a new “best practices” document on Pervasive Monitoring (RFC 7258). This document is extremely sensitive in its approach and separates the politics of monitoring from the technical ones. Pervasive Monitoring (PM) is widespread (and often covert) surveillance through intrusive gathering of protocol artefacts, including application content, or protocol metadata such as headers. Active or passive wiretaps and traffic analysis, (e.g., correlation, timing or measuring packet sizes), or subverting the cryptographic keys used to secure protocols can also be used as part of pervasive monitoring. PM is distinguished by being indiscriminate and very large scale, rather than by introducing new types of technical compromise. The IETF community's technical assessment is that PM is an attack on the privacy of Internet users and organisations. The IETF community has expressed strong agreement that PM is an attack that needs to be mitigated where possible, via the design of protocols that make PM significantly more expensive or infeasible. Pervasive monitoring was discussed at the technical plenary of the November 2013 IETF meeting [IETF88Plenary] and then through extensive exchanges on IETF mailing lists. This document records the IETF community's consensus and establishes the technical nature of PM. The draft goes on to further qualify what it means by “attack”, clarifying that  The term is used here to refer to behavior that subverts the intent of communicating parties without the agreement of those parties. An attack may change the content of the communication, record the content or external characteristics of the communication, or through correlation with other communication events, reveal information the parties did not intend to be revealed. It may also have other effects that similarly subvert the intent of a communicator.  The past year has shown that Internet specification authors need to put more emphasis into information security and integrity. The year also showed that specifications are not good enough. The implementations of security and protocol specifications have to be of high quality and superior testing. I’m proud to say Oracle has been a strong proponent of this, having already established its own secure coding practices. 

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  • Can't connect to certain HTTPS sites

    - by mind.blank
    I've just moved to a new apartment and with internet connection via a router and I'm finding that I can't connect to quite a few sites that use SSL. For example trying to connect to PayPal: curl -v https://paypal.com * About to connect() to paypal.com port 443 (#0) * Trying 66.211.169.3... connected * successfully set certificate verify locations: * CAfile: none CApath: /etc/ssl/certs * SSLv3, TLS handshake, Client hello (1): * Unknown SSL protocol error in connection to paypal.com:443 * Closing connection #0 curl: (35) Unknown SSL protocol error in connection to paypal.com:443 curl -v -ssl https://paypal.com gives the same output. For some sites it works: curl -v https://www.google.com * About to connect() to www.google.com port 443 (#0) * Trying 74.125.235.112... connected * successfully set certificate verify locations: * CAfile: none CApath: /etc/ssl/certs * SSLv3, TLS handshake, Client hello (1): * SSLv3, TLS handshake, Server hello (2): * SSLv3, TLS handshake, CERT (11): * SSLv3, TLS handshake, Server key exchange (12): * SSLv3, TLS handshake, Server finished (14): * SSLv3, TLS handshake, Client key exchange (16): * SSLv3, TLS change cipher, Client hello (1): * SSLv3, TLS handshake, Finished (20): * SSLv3, TLS change cipher, Client hello (1): * SSLv3, TLS handshake, Finished (20): * SSL connection using ECDHE-RSA-RC4-SHA * Server certificate: * subject: C=US; ST=California; L=Mountain View; O=Google Inc; CN=www.google.com * start date: 2011-10-26 00:00:00 GMT * expire date: 2013-09-30 23:59:59 GMT * common name: www.google.com (matched) * issuer: C=ZA; O=Thawte Consulting (Pty) Ltd.; CN=Thawte SGC CA * SSL certificate verify ok. > GET / HTTP/1.1 > User-Agent: curl/7.22.0 (x86_64-pc-linux-gnu) libcurl/7.22.0 OpenSSL/1.0.1 zlib/1.2.3.4 libidn/1.23 librtmp/2.3 > Host: www.google.com > Accept: */* > < HTTP/1.1 302 Found < Location: https://www.google.co.jp/ . . . I'm using Ubuntu 12.04, with Windows 7 installed as well. These sites work on Windows :( Not sure if this information helps but I ran ifconfig and got the following: eth0 Link encap:Ethernet HWaddr 1c:c1:de:bc:e2:4f inet6 addr: 2408:c3:7fff:991:686b:8d18:81b3:8dd1/64 Scope:Global inet6 addr: 2408:c3:7fff:991:1ec1:deff:febc:e24f/64 Scope:Global inet6 addr: fe80::1ec1:deff:febc:e24f/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:87075 errors:0 dropped:0 overruns:0 frame:0 TX packets:54522 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:78167937 (78.1 MB) TX bytes:10016891 (10.0 MB) Interrupt:46 Base address:0x4000 eth1 Link encap:Ethernet HWaddr ac:81:12:0d:93:80 inet6 addr: fe80::ae81:12ff:fe0d:9380/64 Scope:Link UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:498 TX packets:0 errors:26 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) Interrupt:17 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:630 errors:0 dropped:0 overruns:0 frame:0 TX packets:630 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:39592 (39.5 KB) TX bytes:39592 (39.5 KB) ppp0 Link encap:Point-to-Point Protocol inet addr:180.57.228.200 P-t-P:118.23.8.175 Mask:255.255.255.255 UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1492 Metric:1 RX packets:39631 errors:0 dropped:0 overruns:0 frame:0 TX packets:22391 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:3 RX bytes:43462054 (43.4 MB) TX bytes:2834628 (2.8 MB)

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  • Exploring TCP throughput with DTrace

    - by user12820842
    One key measure to use when assessing TCP throughput is assessing the amount of unacknowledged data in the pipe. This is sometimes termed the Bandwidth Delay Product (BDP) (note that BDP is often used more generally as the product of the link capacity and the end-to-end delay). In DTrace terms, the amount of unacknowledged data in bytes for the connection is the different between the next sequence number to send and the lowest unacknoweldged sequence number (tcps_snxt - tcps_suna). According to the theory, when the number of unacknowledged bytes for the connection is less than the receive window of the peer, the path bandwidth is the limiting factor for throughput. In other words, if we can fill the pipe without the peer TCP complaining (by virtue of its window size reaching 0), we are purely bandwidth-limited. If the peer's receive window is too small however, the sending TCP has to wait for acknowledgements before it can send more data. In this case the round-trip time (RTT) limits throughput. In such cases the effective throughput limit is the window size divided by the RTT, e.g. if the window size is 64K and the RTT is 0.5sec, the throughput is 128K/s. So a neat way to visually determine if the receive window of clients may be too small should be to compare the distribution of BDP values for the server versus the client's advertised receive window. If the BDP distribution overlaps the send window distribution such that it is to the right (or lower down in DTrace since quantizations are displayed vertically), it indicates that the amount of unacknowledged data regularly exceeds the client's receive window, so that it is possible that the sender may have more data to send but is blocked by a zero-window on the client side. In the following example, we compare the distribution of BDP values to the receive window advertised by the receiver (10.175.96.92) for a large file download via http. # dtrace -s tcp_tput.d ^C BDP(bytes) 10.175.96.92 80 value ------------- Distribution ------------- count -1 | 0 0 | 6 1 | 0 2 | 0 4 | 0 8 | 0 16 | 0 32 | 0 64 | 0 128 | 0 256 | 3 512 | 0 1024 | 0 2048 | 9 4096 | 14 8192 | 27 16384 | 67 32768 |@@ 1464 65536 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 32396 131072 | 0 SWND(bytes) 10.175.96.92 80 value ------------- Distribution ------------- count 16384 | 0 32768 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 17067 65536 | 0 Here we have a puzzle. We can see that the receiver's advertised window is in the 32768-65535 range, while the amount of unacknowledged data in the pipe is largely in the 65536-131071 range. What's going on here? Surely in a case like this we should see zero-window events, since the amount of data in the pipe regularly exceeds the window size of the receiver. We can see that we don't see any zero-window events since the SWND distribution displays no 0 values - it stays within the 32768-65535 range. The explanation is straightforward enough. TCP Window scaling is in operation for this connection - the Window Scale TCP option is used on connection setup to allow a connection to advertise (and have advertised to it) a window greater than 65536 bytes. In this case the scaling shift is 1, so this explains why the SWND values are clustered in the 32768-65535 range rather than the 65536-131071 range - the SWND value needs to be multiplied by two since the reciever is also scaling its window by a shift factor of 1. Here's the simple script that compares BDP and SWND distributions, fixed to take account of window scaling. #!/usr/sbin/dtrace -s #pragma D option quiet tcp:::send / (args[4]-tcp_flags & (TH_SYN|TH_RST|TH_FIN)) == 0 / { @bdp["BDP(bytes)", args[2]-ip_daddr, args[4]-tcp_sport] = quantize(args[3]-tcps_snxt - args[3]-tcps_suna); } tcp:::receive / (args[4]-tcp_flags & (TH_SYN|TH_RST|TH_FIN)) == 0 / { @swnd["SWND(bytes)", args[2]-ip_saddr, args[4]-tcp_dport] = quantize((args[4]-tcp_window)*(1 tcps_snd_ws)); } And here's the fixed output. # dtrace -s tcp_tput_scaled.d ^C BDP(bytes) 10.175.96.92 80 value ------------- Distribution ------------- count -1 | 0 0 | 39 1 | 0 2 | 0 4 | 0 8 | 0 16 | 0 32 | 0 64 | 0 128 | 0 256 | 3 512 | 0 1024 | 0 2048 | 4 4096 | 9 8192 | 22 16384 | 37 32768 |@ 99 65536 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 3858 131072 | 0 SWND(bytes) 10.175.96.92 80 value ------------- Distribution ------------- count 512 | 0 1024 | 1 2048 | 0 4096 | 2 8192 | 4 16384 | 7 32768 | 14 65536 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ 1956 131072 | 0

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  • Why are you doing this? [closed]

    - by NIcholas Lawson
    I am working on a story that I am going to be querying to several magazines in my hometown about this work that is being done by the AXR group. This is a group of people who have networked online and are working on developing a higher level syntax structure than CSS and HTML currently offer. I am covering this is as a story because I see potential in this as a human interest story in cosmopolitan society. I have been asked by the group to pose this question to you and would appreciate any and all comments you would have on the following ... To AXR: So when does the internet become finished? At what point does a computer scientist say to himself ... my job here is finished ... the internet is complete? When is the internet ready to be more about the display of content than the uploading of new websites or computer tech? You are embarking on upon a sixty year project every day you work with this internet, what drives you? Why are you spending your hard earned hours working on the code to this computer? I spend thirty hours a week online because I love the writing and I know what would make the internet better ... ease of use ... i know it is difficult to program but I see some very elegant solutions online ... in this early inception phase of your programming development for this HSS prototype ... I would like to know why I do not see you programmers asking questions such as ... What would make the end user's life the easiest when using this code? I know you can solve the problem but an evolution forward would be simple, not simple to a computer scientist but simple to use for a career janitor ... if you could solve the problem of alleviating the stress at using a the computer you could get better content out of the computer ... right now the main problem is that the best content is in the hands of the people least likely to use the computer and the more simple you make the computer to use ... the better the content collection will be in the long run ... That is not what I want to talk about though ... why are you writing code when you could be writing stories? I know the computer is worthless without content so I build content, I know the book is worthless without the combinations of words in them, i know the television is worthless without the television news anchor or the actor, what I want to know from you folks in a very journalistic sense is why are you even bothering to bother to write code for a machine that has only made our lives i would dare say less interesting. why are you feeding the beast your time when you could be writing stories or being an actor or musician or auto mechanic ... why code? why this machine? what do you love about it? what do you hate about it? what do you wonder about it? I want to know so that starting out I know how to further shape my questions with axr ... i want the full story ... i want the real answers ... and i want to know why you are doing this, it would make for great writing if you could elucidate on this point.

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  • NFS issue brings down entire vSphere ESX estate

    - by growse
    I experienced an odd issue this morning where an NFS issue appeared to have taken down the majority of my VMs hosted on a small vSphere 5.0 estate. The infrastructure itself is 4x IBM HS21 blades running around 20 VMs. The storage is provided by a single HP X1600 array with attached D2700 chassis running Solaris 11. There's a couple of storage pools on this which are exposed over NFS for the storage of the VM files, and some iSCSI LUNs for things like MSCS shared disks. Normally, this is pretty stable, but I appreciate the lack of resiliancy in having a single X1600 doing all the storage. This morning, in the logs of each ESX host, at around 0521 GMT I saw a lot of entries like this: 2011-11-30T05:21:54.161Z cpu2:2050)NFSLock: 608: Stop accessing fd 0x41000a4cf9a8 3 2011-11-30T05:21:54.161Z cpu2:2050)NFSLock: 608: Stop accessing fd 0x41000a4dc9e8 3 2011-11-30T05:21:54.161Z cpu2:2050)NFSLock: 608: Stop accessing fd 0x41000a4d3fa8 3 2011-11-30T05:21:54.161Z cpu2:2050)NFSLock: 608: Stop accessing fd 0x41000a4de0a8 3 [....] 2011-11-30T06:16:07.042Z cpu0:2058)WARNING: NFS: 283: Lost connection to the server 10.13.111.197 mount point /sastank/VMStorage, mounted as f0342e1c-19be66b5-0000-000000000000 ("SAStank") 2011-11-30T06:17:01.459Z cpu2:4011)NFS: 292: Restored connection to the server 10.13.111.197 mount point /sastank/VMStorage, mounted as f0342e1c-19be66b5-0000-000000000000 ("SAStank") 2011-11-30T06:25:17.887Z cpu3:2051)NFSLock: 608: Stop accessing fd 0x41000a4c2b28 3 2011-11-30T06:27:16.063Z cpu3:4011)NFSLock: 568: Start accessing fd 0x41000a4d8928 again 2011-11-30T06:35:30.827Z cpu1:2058)WARNING: NFS: 283: Lost connection to the server 10.13.111.197 mount point /tank/ISO, mounted as 5acdbb3e-410e56e3-0000-000000000000 ("ISO (1)") 2011-11-30T06:36:37.953Z cpu6:2054)NFS: 292: Restored connection to the server 10.13.111.197 mount point /tank/ISO, mounted as 5acdbb3e-410e56e3-0000-000000000000 ("ISO (1)") 2011-11-30T06:40:08.242Z cpu6:2054)NFSLock: 608: Stop accessing fd 0x41000a4c3e68 3 2011-11-30T06:40:34.647Z cpu3:2051)NFSLock: 568: Start accessing fd 0x41000a4d8928 again 2011-11-30T06:44:42.663Z cpu1:2058)WARNING: NFS: 283: Lost connection to the server 10.13.111.197 mount point /sastank/VMStorage, mounted as f0342e1c-19be66b5-0000-000000000000 ("SAStank") 2011-11-30T06:44:53.973Z cpu0:4011)NFS: 292: Restored connection to the server 10.13.111.197 mount point /sastank/VMStorage, mounted as f0342e1c-19be66b5-0000-000000000000 ("SAStank") 2011-11-30T06:51:28.296Z cpu5:2058)NFSLock: 608: Stop accessing fd 0x41000ae3c528 3 2011-11-30T06:51:44.024Z cpu4:2052)NFSLock: 568: Start accessing fd 0x41000ae3b8e8 again 2011-11-30T06:56:30.758Z cpu4:2058)WARNING: NFS: 283: Lost connection to the server 10.13.111.197 mount point /sastank/VMStorage, mounted as f0342e1c-19be66b5-0000-000000000000 ("SAStank") 2011-11-30T06:56:53.389Z cpu7:2055)NFS: 292: Restored connection to the server 10.13.111.197 mount point /sastank/VMStorage, mounted as f0342e1c-19be66b5-0000-000000000000 ("SAStank") 2011-11-30T07:01:50.350Z cpu6:2054)ScsiDeviceIO: 2316: Cmd(0x41240072bc80) 0x12, CmdSN 0x9803 to dev "naa.600508e000000000505c16815a36c50d" failed H:0x0 D:0x2 P:0x0 Valid sense data: 0x5 0x24 0x0. 2011-11-30T07:03:48.449Z cpu3:2051)NFSLock: 608: Stop accessing fd 0x41000ae46b68 3 2011-11-30T07:03:57.318Z cpu4:4009)NFSLock: 568: Start accessing fd 0x41000ae48228 again (I've put a complete dump from one of the hosts on pastebin: http://pastebin.com/Vn60wgTt) When I got in the office at 9am, I saw various failures and alarms and troubleshooted the issue. It turned out that pretty much all of the VMs were inaccessible, and that the ESX hosts either were describing each VM as 'powered off', 'powered on', or 'unavailable'. The VMs described as 'powered on' where not in any way reachable or responding to pings, so this may be lies. There's absolutely no indication on the X1600 that anything was awry, and nothing on the switches to indicate any loss of connectivity. I only managed to resolve the issue by rebooting the ESX hosts in turn. I have a number of questions: What the hell happened? If this was a temporary NFS failure, why did it put the ESX hosts into a state from which a reboot was the only recovery? In the future, when the NFS server goes a little off-piste, what would be the best approach to add some resilience? I've been looking at budgeting for next year and potentially have budget to purchase another X1600/D2700/disks, would an identical mirrored disk setup help to mitigate these sorts of failures automatically? Edit (Added requested details) To expand with some details as requested: The X1600 has 12x 1TB disks lumped together in mirrored pairs as tank, and the D2700 (connected with a mini SAS cable) has 12x 300GB 10k SAS disks lumped together in mirrored pairs as sastank zpool status pool: rpool state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM rpool ONLINE 0 0 0 c7t0d0s0 ONLINE 0 0 0 errors: No known data errors pool: sastank state: ONLINE scan: scrub repaired 0 in 74h21m with 0 errors on Wed Nov 30 02:51:58 2011 config: NAME STATE READ WRITE CKSUM sastank ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 c7t14d0 ONLINE 0 0 0 c7t15d0 ONLINE 0 0 0 mirror-1 ONLINE 0 0 0 c7t16d0 ONLINE 0 0 0 c7t17d0 ONLINE 0 0 0 mirror-2 ONLINE 0 0 0 c7t18d0 ONLINE 0 0 0 c7t19d0 ONLINE 0 0 0 mirror-3 ONLINE 0 0 0 c7t20d0 ONLINE 0 0 0 c7t21d0 ONLINE 0 0 0 mirror-4 ONLINE 0 0 0 c7t22d0 ONLINE 0 0 0 c7t23d0 ONLINE 0 0 0 mirror-5 ONLINE 0 0 0 c7t24d0 ONLINE 0 0 0 c7t25d0 ONLINE 0 0 0 errors: No known data errors pool: tank state: ONLINE scan: scrub repaired 0 in 17h28m with 0 errors on Mon Nov 28 17:58:19 2011 config: NAME STATE READ WRITE CKSUM tank ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 c7t1d0 ONLINE 0 0 0 c7t2d0 ONLINE 0 0 0 mirror-1 ONLINE 0 0 0 c7t3d0 ONLINE 0 0 0 c7t4d0 ONLINE 0 0 0 mirror-2 ONLINE 0 0 0 c7t5d0 ONLINE 0 0 0 c7t6d0 ONLINE 0 0 0 mirror-3 ONLINE 0 0 0 c7t8d0 ONLINE 0 0 0 c7t9d0 ONLINE 0 0 0 mirror-4 ONLINE 0 0 0 c7t10d0 ONLINE 0 0 0 c7t11d0 ONLINE 0 0 0 mirror-5 ONLINE 0 0 0 c7t12d0 ONLINE 0 0 0 c7t13d0 ONLINE 0 0 0 errors: No known data errors The filesystem exposed over NFS for the primary datastore is sastank/VMStorage zfs list NAME USED AVAIL REFER MOUNTPOINT rpool 45.1G 13.4G 92.5K /rpool rpool/ROOT 2.28G 13.4G 31K legacy rpool/ROOT/solaris 2.28G 13.4G 2.19G / rpool/dump 15.0G 13.4G 15.0G - rpool/export 11.9G 13.4G 32K /export rpool/export/home 11.9G 13.4G 32K /export/home rpool/export/home/andrew 11.9G 13.4G 11.9G /export/home/andrew rpool/swap 15.9G 29.2G 123M - sastank 1.08T 536G 33K /sastank sastank/VMStorage 1.01T 536G 1.01T /sastank/VMStorage sastank/comstar 71.7G 536G 31K /sastank/comstar sastank/comstar/sql_tempdb 6.31G 536G 6.31G - sastank/comstar/sql_tx_data 65.4G 536G 65.4G - tank 4.79T 578G 42K /tank tank/FTP 269G 578G 269G /tank/FTP tank/ISO 28.8G 578G 25.9G /tank/ISO tank/backupstage 2.64T 578G 2.49T /tank/backupstage tank/cifs 301G 578G 297G /tank/cifs tank/comstar 1.54T 578G 31K /tank/comstar tank/comstar/msdtc 1.07G 579G 32.8M - tank/comstar/quorum 577M 578G 47.9M - tank/comstar/sqldata 1.54T 886G 304G - tank/comstar/vsphere_lun 2.09G 580G 22.2M - tank/mcs-asset-repository 7.01M 578G 6.99M /tank/mcs-asset-repository tank/mscs-quorum 55K 578G 36K /tank/mscs-quorum tank/sccm 16.1G 578G 12.8G /tank/sccm As for the networking, all connections between the X1600, the Blades and the switch are either LACP or Etherchannel bonded 2x 1Gbit links. Switch is a single Cisco 3750. Storage traffic sits on its own VLAN segregated from VM machine traffic.

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  • Installing the Elgg Social Networking CMS

    One Open Source CMS that stands out above the rest for small businesses and personal networks is the Elgg open source "social engine," which can be used to create social applications. Scott Clark shows you how to install and get started with this social networking CMS.

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  • Unable to import Maven project into IntelliJ IDEA

    - by del
    I'm having problems importing any Maven projects into IntelliJ IDEA. I create an empty Maven project like this: $ mvn archetype:generate -DgroupId=com.mycompany.app -DartifactId=my-app -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false Then I try to open the project in IDEA (File Open Project, then choose the pom.xml). A progress box saying "Reading pom.xml" displays for a few minutes, and then just disappears without opening the project. Looking in the IDEA log, I see some connection timeout exceptions like this: 2012-10-03 11:55:55,483 [ 16981] INFO - ution.rmi.RemoteProcessSupport - Port/ID: 18011/Maven2ServerImpl9407569f 2012-10-03 11:56:58,898 [ 80396] WARN - ution.rmi.RemoteProcessSupport - The cook failed to start due to java.net.ConnectException: Connection timed out 2012-10-03 11:57:55,483 [ 136981] WARN - ution.rmi.RemoteProcessSupport - java.rmi.NotBoundException: _DEAD_HAND_ 2012-10-03 11:57:55,484 [ 136982] WARN - ution.rmi.RemoteProcessSupport - at sun.rmi.registry.RegistryImpl.lookup(RegistryImpl.java:106) 2012-10-03 11:57:55,484 [ 136982] WARN - ution.rmi.RemoteProcessSupport - at com.intellij.execution.rmi.RemoteServer.start(RemoteServer.java:73) 2012-10-03 11:57:55,484 [ 136982] WARN - ution.rmi.RemoteProcessSupport - at org.jetbrains.idea.maven.server.RemoteMavenServer.main(RemoteMavenServer.java:22) 2012-10-03 11:58:01,749 [ 143247] ERROR - com.intellij.ide.IdeEventQueue - Error during dispatching of java.awt.event.MouseEvent[MOUSE_RELEASED,(65,116),absolute(64,140),button=1,modifiers=Button1,clickCount=1] on frame0 java.lang.RuntimeException: Cannot reconnect. at org.jetbrains.idea.maven.server.RemoteObjectWrapper.perform(RemoteObjectWrapper.java:82) at org.jetbrains.idea.maven.server.MavenServerManager.applyProfiles(MavenServerManager.java:311) at org.jetbrains.idea.maven.project.MavenProjectReader.applyProfiles(MavenProjectReader.java:369) at org.jetbrains.idea.maven.project.MavenProjectReader.doReadProjectModel(MavenProjectReader.java:98) at org.jetbrains.idea.maven.project.MavenProjectReader.readProject(MavenProjectReader.java:52) at org.jetbrains.idea.maven.project.MavenProject.read(MavenProject.java:405) at org.jetbrains.idea.maven.project.MavenProjectsTree.doUpdate(MavenProjectsTree.java:534) at org.jetbrains.idea.maven.project.MavenProjectsTree.doAdd(MavenProjectsTree.java:481) at org.jetbrains.idea.maven.project.MavenProjectsTree.update(MavenProjectsTree.java:442) at org.jetbrains.idea.maven.project.MavenProjectsTree.updateAll(MavenProjectsTree.java:413) at org.jetbrains.idea.maven.wizards.MavenProjectBuilder.readMavenProjectTree(MavenProjectBuilder.java:198) at org.jetbrains.idea.maven.wizards.MavenProjectBuilder.access$800(MavenProjectBuilder.java:44) at org.jetbrains.idea.maven.wizards.MavenProjectBuilder$3.run(MavenProjectBuilder.java:179) at org.jetbrains.idea.maven.utils.MavenUtil$8.run(MavenUtil.java:388) at com.intellij.openapi.progress.impl.ProgressManagerImpl$TaskRunnable.run(ProgressManagerImpl.java:469) at com.intellij.openapi.progress.impl.ProgressManagerImpl$6.run(ProgressManagerImpl.java:288) at com.intellij.openapi.progress.impl.ProgressManagerImpl$2.run(ProgressManagerImpl.java:178) at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:218) at com.intellij.openapi.progress.impl.ProgressManagerImpl.runProcess(ProgressManagerImpl.java:169) at com.intellij.openapi.application.impl.ApplicationImpl$8$1.run(ApplicationImpl.java:641) at com.intellij.openapi.application.impl.ApplicationImpl$6.run(ApplicationImpl.java:434) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303) at java.util.concurrent.FutureTask.run(FutureTask.java:138) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:662) at com.intellij.openapi.application.impl.ApplicationImpl$1$1.run(ApplicationImpl.java:145) Caused by: java.rmi.RemoteException: Cannot start maven service; nested exception is: java.rmi.ConnectException: Connection refused to host: localhost; nested exception is: java.net.ConnectException: Connection timed out at org.jetbrains.idea.maven.server.MavenServerManager.create(MavenServerManager.java:120) at org.jetbrains.idea.maven.server.MavenServerManager.create(MavenServerManager.java:71) at org.jetbrains.idea.maven.server.RemoteObjectWrapper.getOrCreateWrappee(RemoteObjectWrapper.java:41) at org.jetbrains.idea.maven.server.MavenServerManager$8.execute(MavenServerManager.java:314) at org.jetbrains.idea.maven.server.MavenServerManager$8.execute(MavenServerManager.java:311) at org.jetbrains.idea.maven.server.RemoteObjectWrapper.perform(RemoteObjectWrapper.java:76) ... 27 more Caused by: java.rmi.ConnectException: Connection refused to host: localhost; nested exception is: java.net.ConnectException: Connection timed out at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:601) at sun.rmi.transport.tcp.TCPChannel.createConnection(TCPChannel.java:198) at sun.rmi.transport.tcp.TCPChannel.newConnection(TCPChannel.java:184) at sun.rmi.server.UnicastRef.newCall(UnicastRef.java:322) at sun.rmi.registry.RegistryImpl_Stub.lookup(Unknown Source) at com.intellij.execution.rmi.RemoteProcessSupport$2.compute(RemoteProcessSupport.java:215) at com.intellij.execution.rmi.RemoteUtil.executeWithClassLoader(RemoteUtil.java:122) at com.intellij.execution.rmi.RemoteProcessSupport.acquire(RemoteProcessSupport.java:212) at com.intellij.execution.rmi.RemoteProcessSupport.acquire(RemoteProcessSupport.java:133) at org.jetbrains.idea.maven.server.MavenServerManager.create(MavenServerManager.java:117) ... 32 more Caused by: java.net.ConnectException: Connection timed out at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:351) at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:213) at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:200) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366) at java.net.Socket.connect(Socket.java:529) at java.net.Socket.connect(Socket.java:478) at java.net.Socket.(Socket.java:375) at java.net.Socket.(Socket.java:189) at sun.rmi.transport.proxy.RMIDirectSocketFactory.createSocket(RMIDirectSocketFactory.java:22) at sun.rmi.transport.proxy.RMIMasterSocketFactory.createSocket(RMIMasterSocketFactory.java:128) at sun.rmi.transport.tcp.TCPEndpoint.newSocket(TCPEndpoint.java:595) ... 41 more I'm using the latest versions of IDEA (11.1.3) and Maven (3.0.4). Any ideas what I am doing wrong?

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  • Functions connected to signals in QtScript (on Qt 4.5.2) are not firing

    - by Cody Brocious
    I've injected into a proprietary Qt (4.5.2) application, added my own compatible build of QtScript, and have managed to get access to all the signals I need. However, when connecting to them (via QtScript) my functions are never called. I've come up with a few theories for why this is and I've tested everything I can think of, but I've hit a bit of a wall. Note, I've never had any connection exceptions whatsoever. Here are my current theories: The signals I'm connecting to are already connected to other slots, and that's somehow blocking it (but as far as I know, all Qt signals fire to all slots with no extra work, and can't be restricted in this way) The signals are rejecting my connection, or disconnecting me after connection (but I see no facility for this) My connection is happening from another thread, and this is somehow causing it not to connect properly Are any of these theories plausible? If not, what have I missed?

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  • Windows Server 2008 R2: Introducing the AD Administrative Center

    The Active Directory Administrative Center in Windows Server 2008 R2 is a significant improvement over its predecessor. Although not without limitations, it offers beefed-up management of AD objects, new navigation capabilities, better task-based management options, and improvements to the properties page and search capabilities.

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