admin

HOW TO : Check status of bond interface in Linux

For my notes.. If you ever wanted to check the status of a bonded interface configure in Linux (esp RHEL), you can check the status by running the following command

[root@serverxyz bin]# cat /proc/net/bonding/bond0

i.e. assuming the name of your bond interface is bond0.

Output from the command

Ethernet Channel Bonding Driver: v3.4.0 (October 7, 2008)

Bonding Mode: fault-tolerance (active-backup)
Primary Slave: eth3 (primary_reselect always)
Currently Active Slave: eth3
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 0
Down Delay (ms): 0

Slave Interface: eth3
MII Status: up
Link Failure Count: 0
Permanent HW addr: 00:10:18:6e:b8:1a

Slave Interface: eth0
MII Status: up
Link Failure Count: 0
Permanent HW addr: 00:21:5e:11:34:32

The configuration files involved are

/etc/sysconfig/network-scripts/ifcfg-bond0 (Bond Interface)

DEVICE=bond0
IPADDR=10.10.40.26
NETMASK=255.255.255.0
ONBOOT=yes
BOOTPROTO=none
USERCTL=no
GATEWAY=10.10.40.1
NETWORK=10.10.40.0
BROADCAST=10.10.40.255
TYPE=Ethernet

/etc/sysconfig/network-scripts/ifcfg-eth3 (Primary Interface)

DEVICE=eth3
BOOTPROTO=none
ONBOOT=yes
HWADDR=00:10:18:6e:b8:1a
MASTER=bond0
SLAVE=yes
TYPE=Ethernet
USERCTL=no

/etc/sysconfig/network-scripts/ifcfg-eth0 (Secondary Interface)

DEVICE=eth0
HWADDR=00:21:5e:11:34:32
USERCTL=no
ONBOOT=yes
MASTER=bond0
SLAVE=yes
BOOTPROTO=none
TYPE=Ethernet
July 30, 2010 by HOWTO Linux Networking Technology Uncategorized 11

Lessons of the Trade : Purging Databases

We ran into an interesting issue at work recently. Documenting the solution for my records..

BACKGROUND : We had a table in one of our databases that served as a “hopping” point for some jobs. Data was inserted into this table and at jobs get kicked off at periodic intervals to “process” the data and delete it.

CURRENT METHOD : Launch multiple jobs to process the data and delete the rows as soon as the data is processed. This is causing locks on the table because there are multiple delete operations occurring at the same time. Which in turn means that the jobs cannot complete processing the data causing the table to grow in size.

PROPOSED METHOD : Add a new column to the table called “PROCESSED_STATE” and modify the “processing” jobs to set a flag “Y” in this column as soon as the data is processed. Create a new job that will be launched periodically, which checks the PROCESSED_STATE column and if the flag is set to “Y”, deletes the row.

Morale of the story.. 🙂 .. Multiple deletes on a table are bad. Better way is to have multiple updates and one delete.

July 12, 2010 by Databases Technology Uncategorized 0

What happens when you get busy (lazy)?

Your site goes down 🙂

And traffic to the site drops!!

Things have been a bit crazy at work recently, so I didn’t get a chance to fix the site as soon as it went down (due to an error I still haven’t figured out). And as a result, the traffic to the site dropped.

I finally took the chance to move the site to a dedicated server running on the RackSpace Cloud services. Am putting together a post on how I handled this migration and will publish it soon.

The bad news is that I have lost traffic to the site that I have built over a period of time.. the good news is that I am the master of my own house (website) at last :).

June 16, 2010 by Technology Uncategorized 0

I like to be in control of my destiny

I don’t have a Facebook or twitter account and that surprises a lot of my friends since I am such a geek :). And the reason I keep (kept) giving was that I want to be in control of my destiny. In this case, destiny being content. While Facebook and Twitter provide you with a easy way to connect with friends/relatives/stalkers etc, I believe it gives a lot of leeway on control over the content for the companies running these applications. I have all the means and ways to communicate with my friends and advertise what I need to world. How I do that? That is a blog post that I have been “drafting” for the last couple of months :)..Hope to publish it soon. And looks like the wider audience is finally waking up to it.

Check out this article on ReadWriteWeb regd how the tech leaders are calling for a boycott of Facebook and advocating for an open social networking protocol (http://www.readwriteweb.com/archives/more_web_industry_leaders_quit_facebook_call_for_o.php).

Another article on the same website, speaks about a study by the Advanced Institute of Science and Technology in Korea, which shows that Twitter is really not a social networking site, but more of a medium to broadcast your content (http://www.readwriteweb.com/archives/study_twitter_isnt_very_social.php). Doesn’t really support the argument I made earlier that Twitter is not going to make it..but it certainly supports the notion that once the hype is gone the influence of twitter as a medium will decrease.

May 12, 2010 by Rantings Technology Uncategorized Web 0

Express.com DNS outage

I am sure a lot of people shop on express.com , but I probably get the credits for being the first blogger to post that express.com has not been responding to DNS queries since ~7:00 PM CST (4/26). Looks like Qwest is hosting DNS for Express. The name servers (most probably global load balancers) are not responding to DNS requests.

Here’s what I get, when I queried for www.express.com

Nameserver trace for www.express.com:

  • Looking for who is responsible for root zone and followed h.root-servers.net.
  • Looking for who is responsible for com and followed h.gtld-servers.net.
  • Looking for who is responsible for express.com and followed dca-ans-01.inet.qwest.net.

Nameservers for www.express.com:

  • dca-ans-01.inet.qwest.net returned (NORECORDS)
  • svl-ans-01.inet.qwest.net returned (NORECORDS)

I feel for the poor ops team scrambling around to bring up the service :). Another reason, you want diversity in your DNS hosting.

April 26, 2010 by Networking Technology Uncategorized Web 0

HOW TO : Configure mime type mappings in Jboss

Instructions for configuring the mime type mappings in Jboss. Mime types essentially tells the application processing the content (typically a browser), what the content is. More information here (http://en.wikipedia.org/wiki/Internet_media_type).

  • Locate the web.xml file for your Jboss instance. It is usually in $JBOSS_HOME/server/INSTANCE/deploy/jboss-web.deployer/conf/web.xml
  • Locate the setting <mime-mapping> and make the required edits. For example, the code for defining the mime type for javascript looks like this



js
application/javascript

  • Restart Jboss
April 12, 2010 by HOWTO Technology Uncategorized Web 0

True Leadership..

As I was channel browsing yesterday, I happened to run across an episode of NOW on my local PBS station. It featured a Harvard educated man that decided to run for the mayor of a rundown steel belt town (Braddock, PA). Besides being impressed and humbled by Mr.John Fetterman, I thought he displayed all the characteristics of a true leader (IMHO).

  • Having a Vision
  • Committing to the Vision
  • Thinking out of the box to implement vision
  • Thinking objectively

Highly recommend watching the video, if you have the time 🙂

April 12, 2010 by Management Uncategorized 1

Industry Jargon : Hotel Industry

For my records..

  • ARI : Availability Rate Inventory. Any transaction that is querying/updating these three items is terms as ARI updates.
  • REVPAR : Revenue Per Available Room. This is the revenue the hotel makes per room in the hotel.
  • Total Pricing : The total price a customer has to pay to book a room in a hotel. It kinda sounds obvious..but when you understand that the total price depends on
    1. The price the hotel wants to charge (which again depends on who is selling the room)
    2. The tax at the city/state level
    3. The price of additions (services like Internet access, breakfast etc)
    4. Commission of the middleman.

It becomes a big deal :).

April 6, 2010 by Hotel Industry Jargon Uncategorized 0