Leo on Tech

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  • At Impact 2010

    I’m in Las Vegas Saturday through Thursday for Impact 2010. Drop me a word if you are there too.Impact 2010

    Having built the DB2 images for WebSphere CloudBurst, I’ll be helping Dustin Amrhein run a lab on Tuesday:

    Hands-on Lab with WebSphere CloudBurst Appliance
    Tuesday at 1:30 PM
    TDC-1369A
    Venetian, San Polo 3403

    I’ll also spend a lot of time demoing and discussing DB2 and WAS cloud images at the RightScale pedestal:Getting Started

    Run DB2 and WebSphere in the Cloud with RightScale
    Demo at ped A3

    Oh, and if you are looking for a hard copy of the legendary Getting Started with DB2 Express-C book, be sure to drop by.

  • iptables pitfall

    An important thing to remember about rulesets in /etc/sysconfig/iptables is that they are chains. The first rule is applied, followed by the second, and so on. It’s the opposite of CSS that way. More specific rules should go first, while all-encompassing rules should go last.

    I was trying to open the usual DB2 ports on RHEL. For some reason, nothing was working.

    It turned out that this line was at fault:

    -A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited

    This rejects all incoming traffic not otherwise allowed. The line has to go last in the file, after all the open port definitions.

  • Interesting IDE prototype

    This video demos an interesting prototype of a new UI for Java IDEs. I am not convinced, but it is worth watching for a new perspective:
    [youtube https://www.youtube.com/watch?v=PsPX0nElJ0k&hl=en_US&fs=1&&w=640&h=505]

  • Donate

    My friend and a great sf author Dr Peter Watts has just been beaten up by US border guards and charged with assaulting an officer. This kangaroo circus might end with a two year imprisonment. Please give what you can to his legal defense fund.

    Story:
    Boing Boing

    Send money via Paypal to:
    donate@rifters.com

    I just donated $50. Cory Doctorow gave $1000. Contesting criminal charges in US court gets very expensive, so every little bit matters.

  • CASCON Deploying MediaWiki with DB2 in the Cloud workshop

    I’m hosting a workshop today at CASCON. The resources for it are below.

    Materials

    Resources

    Downloads

  • Easy OLTP scaling

    OLTP is a database use where there are lots and lots of simple transactions or queries. For example, a typical website uses a database in the OLTP way. This is in contrast to a data warehouse, where there is usually only a few complex queries for generating reports.

    IBM just announced DB2 pureScale, a way of easily scaling up the number of transactions a database can handle. The scaling is horizontal, in the sense that it’s accomplished by adding more servers rather than making the servers bigger.

    DB2 pureScale is:

    • Transparent. Client applications don’t need to know how many database servers there are or which one they are accessing.
    • Easy. Adding a new machine is a matter of running two commands.
    • Resilient. If one node goes down, the other nodes take over and there is virtually no data loss.

    There is an upcoming Chat with the Lab about it:

    DB2 pureScale: Scaling Databases without Limits
    Event Date: 10/21/2009
    Event Time: 11:30 – 13:00 EDT (GMT-04:00)
    Hosted By: Rav Ahuja (IBM)
    Presented By: Sal Vella (IBM), Matt Huras (IBM), Aamer Sachedina (IBM)

    Register now

  • MediaWiki with DB2 support 1.16alpha

    MediaWiki 1.15 was released with partial DB2 support, but unfortunately there were some changes to the database schema that I missed and it didn’t work out of the box. Since then, I’ve committed several fixes to the main development trunk. The trunk is currently destined to become 1.16alpha, though theoretically I could backport these to the 1.15 branch.

    My Apache is currently crashing willy-nilly on startup. Hopefully, there are no silly development bugs left in.:-)

  • Error:

    I ran into the following error while converting a virtual machine on a VMWare ESX Server to OVF using the VMWare OVF Tool.

    Disk Transfer Failed
Error: Unable to open NFC target disk

    Googling suggested that a network problem or a permissions problem might be at fault. In fact, it turned out the problem was that someone had started the image on the ESX server mid-way through conversion. The OVF Tool cannot convert a running image — it requires a stopped machine. Stopping the vm made the problem go away.

  • Selection, updation

    In the future, we might all say “updation”.

  • device br0 already exists

    Here’s how you solve either of the following errors on Ubuntu (and possibly Debian):

    device br0 already exists; can't create bridge with the same name
device eth0 is already a member of a bridge; can't enslave it to bridge br1.

    Removing the device specs from /etc/network/interfaces and restarting the network doesn’t actually remove the device if already active. You need to do it manually.

    List the active devices:

    ifconfig | more

    And then do this to any that you don’t want there, such as br0, eth0, eth1, etc:

    ifconfig br0 down
# and so on

    This deactivates the device. At this point you’ll need to restart the network layer twice:

    sudo /etc/init.d/networking restart
sudo /etc/init.d/networking restart

    And you should be sitting pretty. On some systems, networking is known as network, as in:

    sudo /etc/init.d/network restart
sudo /etc/init.d/network restart