I blogged the feature in Jboss to follow sym links here (http://kudithipudi.org/2008/07/25/howto-configure-jboss-to-follow-symbolic-links/). So essentially when Jboss was started, it was checking all the content in these network path to check for applications to deploy. And traversing a network share with 1000s of directories isn’t fun ..

We fixed it by making a simple edit to the start up script. Here’s the psuedo code for the script

1. Remove soft links to network share
2. Start Jboss
3. Put soft links to network share

And now the application starts in less than a minute .

I guess there might be other elegant ways to do this. i.e. Configure Jboss to only deploy certain applications, but this did the trick for us .

HDD Testing :

I found a pretty interesting tool called Iozone written by William Norcott (Oracle) and Don Capps. You can get the source code and builds for major OSs at http://iozone.org . Despite installing the program using RPM, we were not able to  run the program without specifying the complete path.

There are a ton of options for the program, but the easiest method to run it was in automated mode with the output going to an Excel spreadsheet (more like a glorified CSV file ). Here is the command we used

/opt/iozone/bin/iozone -a -Rb output_excel_file.xls

The “-a” is to tell the program in automated mode and the “-Rb” is to tell the program to format the output in Excel format. And you can then go ahead and open the spreadsheet in Excel and create 3D graphs to check and compare the output.

Network Testing :

Most of the information out there in terms of testing the network stack of a machine is either to copy large files over a network share or via FTP. We didn’t find that was enough to really max out a Gigport since there were protocol limitations that didn’t allow us to saturate the network port. After some searching, we stumbled across a tool called “ettcp” on Sourceforge. ettcp itself is an offshoot of ttcp. ttcp (stands for test tcp) was created to test network performance between two nodes. I couldn’t find any place to download ttcp itself, but you can download ettcp at http://ettcp.sourceforge.net/.

We used a server, to act as a common receiver for all the servers we intended to do a performance test on. Here are the commands we used to run the test

RECEIVER (Common Server)
./ettcp -r -s -f M

The options are

• “-r” for designating the machine as receiver
• “-f M” for showing the output in Mega Bytes.

TRANSMITTER (Test Servers)
./ettcp -t -s receiver_hostname -n 10000000 -f M

the options are

• “-t” for designating the machine as transmitter
• “-s receiver_hostname” to define the receiver
• “-n” to define the number of packets to send to the receiver

socket options = TCP_NODELAY IPTOS_LOWDELAY SO_SNDBUF=8192 SO_RCVBUF=8192

The receive and send buffer seem to do the trick.

/sbin/ifconfig | grep -B1 10.10.10.10 | awk '{if (NR==1) print $1}'

The same script can be changes a bit to support other operating systems too. Essentially, I am doing a grep (search) of the output of ifconfig, which shows all the network information on the system for a particular IP. At the same time, I am using the -B1 option, which will show the line above the matching line. Finally, I am piping this to awk and printing the first row in the first column.

For example, I want to start Oracle while I am logged in as another user (vinay), I can start the database using dbstart by issues

"sudo su - oracle -c "dbstart /$ORACLE_HOME"

$ORACLE_HOME is an environmental variable listed under user oracle’s environment.

Needless to say, you need to ensure that you have sudo configured to allow your userID to su to oracle.

• Edit the main.cf file (the default location is in /etc/postfix) and add “transport_maps = hash:/etc/postfix/transport” (without the quotes) to the file.
• Create a file named “transport” in /etc/postfix, if it doesn’t exist
• Add the following at the end of the transport file

DOMAIN1 :
DOMAIN2 :
* discard:


• Run “postmap /etc/transport” to create a hash of the transport file
• Run “service postfix restart” to restart the postfix service

This configuraiton will ensure that all e-mails address to DOMAIN1 and DOMAIN2 are delivered normally, but the rest of the e-mails are silently discarded.

Note : Ensure that you follow the syntax for where to place the : verbatim.

To expire any cached security permissions, so that sudo is forced to check the sudoers files, issue the following command

sudo -k

links NAME_OF_HTML_FILE

Links displays the HTML code in the page by default..If you want to just view the rendered HTML, press “\” and you can toggle between HTML and Text views.

P.S : You need to have links installed to use it .. But most of the new distributions have it installed by default.