G E N: 2007

Wednesday, September 5, 2007

RPM Commands to Install, Uninstall, Upgrade, Query RPM Packages

RPM command is used for installing, uninstalling, upgrading, querying, listing, and checking RPM packages on your Linux system. RPM stands for Red Hat Package Manager.With root privilege, you can use the rpm command with appropriate options to manage the RPM software packages. Let us take an rpm of Mysql Client and run through all our examples.

Installing a RPM package Using rpm -ivh

RPM filename has packagename, version, release and architecture name.
For example, In the MySQL-client-3.23.57-1.i386.rpm file:
MySQL-client – Package Name
3.23.57 – Version
1 – Release
i386 – Architecture

When you install a RPM, it checks whether your system is suitable for the software the RPM package contains, figures out where to install the files located inside the rpm package, installs them on your system, and adds that piece of software into its database of installed RPM packages.

The following rpm command installs Mysql client package.
# rpm -ivh MySQL-client-3.23.57-1.i386.rpm
Preparing... ########################################### [100%]
1:MySQL-client ########################################### [100%]
rpm command and options
-i : install a package
-v : verbose
-h : print hash marks as the package archive is unpacked.

Query all the RPM Packages using rpm -qa

You can use rpm command to query all the packages installed in your system.
# rpm -qa
cdrecord-2.01-10.7.el5
bluez-libs-3.7-1.1
setarch-2.0-1.1
-q query operation
-a queries all installed packages
To identify whether a particular rpm package is installed on your system, combine rpm and grep command as shown below. Following command checks whether cdrecord package is installed on your system.
# rpm -qa | grep 'cdrecord'

Query a Particular RPM Package using rpm -q

The above example lists all currently installed package. After installation of a package to check the installation, you can query a particular package and verify as shown below.
# rpm -q MySQL-client
MySQL-client-3.23.57-1
# rpm -q MySQL
package MySQL is not installed
Note: To query a package, you should specify the exact package name. If the package name is incorrect, then rpm command will report that the package is not installed.

Query RPM Packages in a various format using rpm –queryformat

Rpm command provides an option –queryformat, which allows you to give the header tag names, to list the packages. Enclose the header tag with in {}.
# rpm -qa --queryformat '%{name-%{version}-%{release} %{size}\n'
cdrecord-2.01-10.7 12324
bluez-libs-3.7-1.1 5634
setarch-2.0-1.1 235563

Which RPM package does a file belong to? – Use rpm -qf

Let us say, you have list of files and you would want to know which package owns all these files. rpm command has options to achieve this.
The following example shows that /usr/bin/mysqlaccess file is part of the MySQL-client-3.23.57-1 rpm.
# rpm -qf /usr/bin/mysqlaccess
MySQL-client-3.23.57-1
-f : file name

Locate documentation of a package that owns file using rpm -qdf

Use the following to know the list of documentations, for a package that owns a file. The following command, gives the location of all the manual pages related to mysql package.
# rpm -qdf /usr/bin/mysqlaccess
/usr/share/man/man1/mysql.1.gz
/usr/share/man/man1/mysqlaccess.1.gz
/usr/share/man/man1/mysqladmin.1.gz
/usr/share/man/man1/mysqldump.1.gz
/usr/share/man/man1/mysqlshow.1.gz
-d : refers documentation.

Information about Installed RPM Package using rpm -qi

rpm command provides a lot of information about an installed pacakge using rpm -qi as shown below:
# rpm -qi MySQL-client
Name : MySQL-client Relocations: (not relocatable)
Version : 3.23.57 Vendor: MySQL AB
Release : 1 Build Date: Mon 09 Jun 2003 11:08:28 PM CEST
Install Date: Mon 06 Feb 2010 03:19:16 AM PST Build Host: build.mysql.com
Group : Applications/Databases Source RPM: MySQL-3.23.57-1.src.rpm
Size : 5305109 License: GPL / LGPL
Signature : (none)
Packager : Lenz Grimmer
URL : http://www.mysql.com/
Summary : MySQL - Client
Description : This package contains the standard MySQL clients.

If you have an RPM file that you would like to install, but want to know more information about it before installing, you can do the following:
# rpm -qip MySQL-client-3.23.57-1.i386.rpm
Name : MySQL-client Relocations: (not relocatable)
Version : 3.23.57 Vendor: MySQL AB
Release : 1 Build Date: Mon 09 Jun 2003 11:08:28 PM CEST
Install Date: (not installed) Build Host: build.mysql.com
Group : Applications/Databases Source RPM: MySQL-3.23.57-1.src.rpm
Size : 5305109 License: GPL / LGPL
Signature : (none)
Packager : Lenz Grimmer
URL : http://www.mysql.com/
Summary : MySQL - Client
Description : This package contains the standard MySQL clients.
-i : view information about an rpm
-p : specify a package name

List all the Files in a Package using rpm -qlp

To list the content of a RPM package, use the following command, which will list out the files without extracting into the local directory folder.
$ rpm -qlp ovpc-2.1.10.rpm
/usr/bin/mysqlaccess
/usr/bin/mysqldata
/usr/bin/mysqlperm
/usr/bin/mysqladmin
q : query the rpm file
l : list the files in the package
p : specify the package name

Extracting the files from a RPM package using rpm2cpio and cpio

RPM is a sort of a cpio archive. First, convert the rpm to cpio archive using rpm2cpio command. Next, use cpio command to extract the files from the archive as shown below.
$ rpm2cpio ovpc-2.1.10.rpm | cpio -idmv
./usr/src/ovpc/-5.10.0
./usr/src/ovpc/ovpc-2.1.10/examples
./usr/src/ovpc/ovpc-2.1.10/examples/bin
./usr/src/ovpc/ovpc-2.1.10/examples/lib
./usr/src/ovpc/ovpc-2.1.10/examples/test
.
.
./usr/src/ovpc/ovpc-2.1.10/pcs

$ ls .
usr

List the Dependency Packages using rpm -qRP

To view the list of packages on which this package depends,
# rpm -qRp MySQL-client-3.23.57-1.i386.rpm
/bin/sh
/usr/bin/perl

Find out the state of files in a package using rpm -qsp

The following command is to find state (installed, replaced or normal) for all the files in a RPM package.
# rpm -qsp MySQL-client-3.23.57-1.i386.rpm
normal /usr/bin/msql2mysql
normal /usr/bin/mysql
normal /usr/bin/mysql_find_rows
normal /usr/bin/mysqlaccess
normal /usr/bin/mysqladmin
normal /usr/bin/mysqlbinlog
normal /usr/bin/mysqlcheck
normal /usr/bin/mysqldump
normal /usr/bin/mysqlimport
normal /usr/bin/mysqlshow
normal /usr/share/man/man1/mysql.1.gz
normal /usr/share/man/man1/mysqlaccess.1.gz
normal /usr/share/man/man1/mysqladmin.1.gz
normal /usr/share/man/man1/mysqldump.1.gz
normal /usr/share/man/man1/mysqlshow.1.gz

Verify a Particular RPM Package using rpm -Vp

Verifying a package compares information about the installed files in the package with information about the files taken from the package metadata stored in the rpm database. In the following command, -V is for verification and -p option is used to specify a package name to verify.
# rpm -Vp MySQL-client-3.23.57-1.i386.rpm
S.5....T c /usr/bin/msql2mysql
S.5....T c /usr/bin/mysql
S.5....T c /usr/bin/mysql_find_rows
S.5....T c /usr/bin/mysqlaccess
The character in the above output denotes the following:

S file Size differs
M Mode differs (includes permissions and file type)
5 MD5 sum differs
D Device major/minor number mismatch
L readlink(2) path mismatch
U User ownership differs
G Group ownership differs
T mTime differs

Verify a Package Owning file using rpm -Vf

The following command verify the package which owns the given filename.
# rpm -Vf /usr/bin/mysqlaccess
S.5....T c /usr/bin/mysql

Upgrading a RPM Package using rpm -Uvh

Upgrading a package is similar to installing one, but RPM automatically un-installs existing versions of the package before installing the new one. If an old version of the package is not found, the upgrade option will still install it.
# rpm -Uvh MySQL-client-3.23.57-1.i386.rpm
Preparing... ########################################### [100%]
1:MySQL-client ###########################################

Uninstalling a RPM Package using rpm -e

To remove an installed rpm package using -e as shown below. After uninstallation, you can query using rpm -qa and verify the uninstallation.
# rpm -ev MySQL-client

Verifying all the RPM Packages using rpm -Va

The following command verifies all the installed packages.
# rpm -Va
S.5....T c /etc/issue
S.5....T c /etc/issue.net
S.5....T c /var/service/imap/ssl/seed
S.5....T c /home/httpd/html/horde/ingo/config/backends.php
.
.
S.5....T c /home/httpd/html/horde/ingo/config/prefs.php
S.5....T c /etc/printcap

Thursday, August 2, 2007

Updating a JAR File

The Jar tool provides a u option which you can use to update the contents of an existing JAR file by modifying its manifest or by adding files.
The basic command for adding files has this format:

jar uf jar-file input-file(s)

In this command:

The u option indicates that you want to update an existing JAR file.
The f option indicates that the JAR file to update is specified on the command line.
jar-file is the existing JAR file that's to be updated.
input-file(s) is a space-delimited list of one or more files that you want to add to the Jar file.

Any files already in the archive having the same pathname as a file being added will be overwritten.
When creating a new JAR file, you can optionally use the -C option to indicate a change of directory. For more information, see the Creating a JAR File section.

Examples

Recall that TicTacToe.jar has these contents:

META-INF/MANIFEST.MF
TicTacToe.class
TicTacToe.class
TicTacToe.java
audio/
audio/beep.au
audio/ding.au
audio/return.au
audio/yahoo1.au
audio/yahoo2.au
example1.html
images/
images/cross.gif
images/not.gif

Suppose that you want to add the file images/new.gif to the JAR file. You could accomplish that by issuing this command from the parent directory of the images directory:

jar uf TicTacToe.jar images/new.gif

The revised JAR file would have this table of contents:

META-INF/MANIFEST.MF
TicTacToe.class
TicTacToe.class
TicTacToe.java
audio/
audio/beep.au
audio/ding.au
audio/return.au
audio/yahoo1.au
audio/yahoo2.au
example1.html
images/
images/cross.gif
images/not.gif
images/new.gif

You can use the -C option to "change directories" during execution of the command. For example:

jar uf TicTacToe.jar -C images new.gif

This command would change to the images directory before adding new.gif to the JAR file. The images directory would not be included in the pathname of new.gif when it's added to the archive, resulting in a table of contents that looks like this:

META-INF/MANIFEST.MF
META-INF/MANIFEST.MF
TicTacToe.class
TicTacToe.class
TicTacToe.java
audio/
audio/beep.au
audio/ding.au
audio/return.au
audio/yahoo1.au
audio/yahoo2.au
example1.html
images/
images/cross.gif
images/not.gif
new.gif

Wednesday, June 27, 2007

Seven Questions Employees Should Ask Before Joining a Startup

While most people want to learn related to founders/entrepreneurs and venture capitalists about startups, most people involved in startup endeavors fall under neither of those categories. They’re employees.

There are many benefits associated with joining a startup as an employee at any level (energized work atmosphere, little bureaucracy, upside), but there are many significant risks coupled with them as well. Of course, a prospective employee should ask numerous questions of both his/her role and the company before joining any firm, but there is a set of questions specific to joining a startup that people should pose. I’ve tried to outline what I think are some of the most important questions below. Keep in mind that this is by no means an exhaustive list, merely a suggested seven to get a discussion going. I encourage everyone to suggest additional questions in the comments section below.

Q) If you are receiving employee options, what is the number of fully-diluted outstanding shares?
Typically, option grants are a key component of compensation in a start-up and are often promoted as such. But the details surrounding stock options are often complex and confusing for non financially-oriented individuals. It is best for employees to understand as much as possible about their option grants (this subject could be the topic for an entire series), but the first place to start is to ask how many outstanding shares there are. From that point, one can calculate the percentage of the company an employee will own and a better gauge of the magnitude of this compensation component. It surprises me how many startup employees I know who are excited to have received a grant of x number of options, but never bothered to ask what relative percentage of the company that translates into.

Q) Has there ever been a down round, a flat round, or a CEO change?
Any of these three events are an indicator that the startup has faced some difficulties in the past and may not be on track moving forward. If one of them has occurred, prospective employees should seek out as much information as they can the context of the situation. After all, there are exceptions to blind the assumption that these are a black mark (e.g. a founding CEO stepping aside to make room for professional management could be an indicator of successful growth). However, if any of these issues have arisen, it is a signal to dig deeper into the health of the business.

Q) What is the burn rate and how much cash is in the bank now?
Even if a start-up is successfully executing, it could still face a cash crunch if it is not yet profitable. Employees should ask to find out how much longer the company will ride without the infusion of another round capital. While the actual answer to this question won’t necessarily provide a definitive answer about the ability for the company to access both cash and capital, it will open up a discussion about it.

Q) What is the plan for exit strategy and its timeframe?
The answer to this question is a soft one with many factors, and can always change depending on circumstances. However, it is best to find out management’s view of a possible exit strategy. Is the company pieced together for a quick flip, building for multi-year significant value creation, or plan on holding for the long term as an eventual cash cow (for founder/investors)? These expectations will affect not only how long employees may be working for the company as it exists today, but more importantly, the resulting surrounding corporate culture.

Q) Could you meet the CEO, the founder(s), and those on the management team?
Start-ups are all about the people involved. And there are a small number of people who are largely going to affect the organization. Even if an entry-level employee is going to work in engineering, I think it makes sense for him/her to meet the VP Sales; likewise, a marketing manager should meet the CTO. Yet it might not happen unless the prospective employee requests it. The handful at the top are going to have a profound affect on the future of the company as a whole and the position (regardless of function), and therefore it is best to meet as many people possible in the company possible before joining.

Q) Are there plans in the next six months to hire anyone along the chain-in-command between your position and the CEO?
Start-ups often have key vacant positions open as the companies expand and grow quickly. I recommend explicitly asking if there is an anticipated change in the reporting structure in the foreseeable future, as any modifications or additions (even those a few rungs up in the ladder) could significantly affect employees’ roles and responsibilities.

Q) How many employees did/does/will the company have six month ago, now, six months from now, a year from now?
Employee count is a strong (but not a perfect) proxy for management’s and investors’ outlook on the business. Start-ups hire ahead of growth (or at least predicted growth), which translate into a viable company, a healthy work environment, and future internal opportunities. Financial figures and projections are helpful indicators, certainly, but are often a distortion of the full picture (especially early on in a company’s cycle). The growth in employee count (or lack thereof) directly signals how much work needs to be accomplished how rosy the expectations are.

Friday, May 11, 2007

Weblogic Errors & Resolutions

Change Development Mode to Production mode in Weblogic: Some of you have requested how to change Weblogic start up mode from DEV to production or vice versa. Actually it is very simple. One way to change it is, by simply editing setDomainEnv.cmd which resides in $root_domain/bin folder.

Look for the line that sets the PRODUCTION_MODE script variable: set PRODUCTION_MODE, set false to the value of the PRODUCTION_MODE variable to ensure the server starts in development mode,set true for starting in prod mode. [set PRODUCTION_MODE=false]
Save your changes and exit the text editor.

Authentication Denied - Boot identity not valid: "<11-May-2007 20:00:57 UTC> <Critical> <Security> <BEA-090402> <Authentication denied: Boot identity not valid; The user name and/or password from the boot identity file (boot.properties) is not valid. The boot identity may have been changed since the boot identity file was created. Please edit and update the boot identity file with the proper values of username and password. The first time the updated boot identity file is used to start the server, these new values are encrypted.>" Follow the following steps:

Remove the boot.properties file completely from the managed server directory.
Remove the ManagedServerDir/data/ldap directory completely.
Always keep backup of files before removing it.
Now try to start the server from the command prompt and provide the username/password used to login to the Admin Console.

Recover SerializedSystemIni.Dat When It Gets Corrupted: Follow following steps in order to recover SerializedSystemIni.Dat file:

Go to DOMAIN_HOME/config
Open the config.xml file and remove any encrypted sections from the <credential-encrypted> attributes. Replace its content with “”, Save the file.
Go to DOMAIN_HOME/servers/AdminServer/security
Remove the boot.properties file if exists.
Go to DOMAIN_HOME/security
Remove SerializedSystemInit.dat
Go to DOMAIN_HOME/ and Rename the fileRealm.properties to fileRealm.properties.src, then open fileRealm.properties.src and change all the hashed passwords (encrypted passwords) to clear text passwords.

For example: user.system=0xaxyzb45e6f6c4eefdd1f14495ff739b5536904c to user.system=password
Ensure to use the same password that was set to the domain.
Save the file.

Open a terminal and go to DOMAIN_HOME/bin

Execute source ./setDomainEnv.sh
Then execute (in the same open terminal) the following script to re-generate 'SerializedSystemIni.dat' and 'fileRealm.properties' file:

java weblogic.security.acl.internal.FileRealm fileRealm.properties SerializedSystemIni.dat

Now open startWeblogic.sh located at DOMAIN_HOME/bin and add this line in JAVA_OPTIONS=-Dweblogic.system.StoreBootIdentity=true, This will create boot.properties file. Save the script & Start Weblogic with startWeblogic.sh or startWeblogic.cmd and give enter the user and password when asked.

Exception Snippet: <Dec 31, 2013 2:06:30 PM UTC> <Error> <JTA> <BEA-114089> <User [<anonymous>] is not authorized to invoke ackPrepare on a Coordinator.>
<Dec 31, 2013 2:06:30 PM UTC> <Error> <JTA> <BEA-110495> <User [<anonymous>] is not authorized to invoke AckRollback on a Coordinator.>

Bea Cause and Action are not very useful, i played with 'Cross-domain security' and 'interoperability mode' and reproduce this problem and come across, finally i came to conclusion that these errors only happened when i had a cross domain security enabled (with identical credentials on both domain - or for some reason some one trying to setup global trust along with cross domain security ).

Inter-domain transaction: The domains and all participating resources must have unique names. That is one cannot have a JDBC data source , a server or a domain with the same name as an object in another domain or the domain itself.
Address Already in Use:

ERR: transport error 202: bind failed: Address already in use
Starting weblogic with Java version:
ERROR: transport error 202: bind failed: Address already in use
ERROR: JDWP Transport dt_socket failed to initialize, TRANSPORT_INIT(510)
JDWP exit error AGENT_ERROR_TRANSPORT_INIT(197): No transports initialized [../../../src/share/back/debugInit.c:690]
FATAL ERROR in native method: JDWP No transports initialized, jvmtiError=AGENT_ERROR_TRANSPORT_INIT(197)

Root Cause: Above error comes due to port usage problem, if during server stop/kill process if the port which weblogic server is using not reclaimed by OS and user again issued the command to start the Weblogic server instance then servers try to bind the same port while another process is already running on that port and Weblogic server fails to start.
Solution: This error mostly comes when user forcefully kill the server, so before restart please check all the ports status which weblogic using e.g. http port , ALSB_DEBUG_PORT and DEBUG_PORT by using this command -
netstat –an | grep <port no> # to see which whether this port is active or not.
e.g. netstat –an | grep 9001
If you get the result from above queries then please wait and give some time to OS to reclaim this port, most of scenarios Port will be get free after some time and you can restart the servers again.
In case above port is not getting released it simply means there is some process holding this Port, that process could be existing Weblogic PID or some demon thread, engage your Unix Administrator to find out that process and kill the process.
Also we can bounce the whole server to release this port.
In case of if this problem is coming for ALSB_DEBUG_PORT and DEBUG_PORT , then you can change this port number as well since these port are internal to Weblogic and does not used by any external system communication.

Exception while starting Weblogic Server: Err: Error occurred during initialization of VM
Could not reserve enough space for object heap

Root Cause: You would get better help for this on WebLogic Server or a Java forum. The above problem is a fairly typical JVM and operating system interop issue. On startup JVM tries to reserve a contiguous block of virtual memory for heap and permgen. If it is unable to do so, it fails to start. On 32-bit operating system, virtual memory address space is 4GB, but drivers and operating system processes can breakup the available space into smaller chunks such that Java is not able to allocate a contiguous block that it requires. Any number of things could of caused this to start happening all of a sudden. Anything from a Windows update to installing new hardware or software.
Several Possible Solutions:

Tries to reduce memory allocated to WLS java process. Move down small increments at a time until the server starts e.g. to 2gb/1gb/512m. Perhaps you can get your app to run with reduced memory.
Switch to a 64-bit operating system and a 64-bit JVM. Note that you don't need more than 4GB of actual ram to get a benefit from a 64-bit environment in this case. It is the size of the virtual memory address space that counts. You will need to seek advice on WebLogic Server forum regarding configuring WLS to run with a 64-bit JVM.
Switch to running WLS using Jrockit. I do not believe Jrockit has the contiguous memory requirement.
Do some low-level debugging to identify which drivers or dlls are loaded where in memory and uninstall offenders or attempt to move them. You can find information on this via Google, but I don't really recommend doing this unless you enjoy low-level debugging and have some experience with it.
If above error is coming due to less memory allocated while your JVM need more then try increasing the memory as well in incremental mannerk solution could be increase the Min and Max size of JVM if your server have enough Memory , as a best practise Min and Max size always should be equal so that during Initiliation itself JVM will reserve that much memory.
In setDomainEnv.sh file find out this properties ‘EXTRA_JAVA_PROPERTIES’ and add this lines “-Xms3072m -Xmx3072m” or “-Xms3g –Xmx3g” Or in Weblogic Admin server console, click on server, go to “server start” tab page and specify JVM parameter “-Xms3072m -Xmx3072m” or “-Xms3g –Xmx3g”
Verify the .out file whether changes is getting effected or not.

Err: Could not obtain an exclusive lock to the embedded LDAP data files directory
<31/05/2012 4:32:08 PM EST> <Error> <EmbeddedLDAP> <BEA-171519> <Could not obtain an exclusive lock to the embedded LDAP data files directory: /hta/home/fusion/osb_home/osb_install1/user_projects/domains/vhaosb-dev2/servers/AdminServer/data/ldap/ldapfiles because another WebLogic Server is already using this directory. Ensure that the first WebLogic Server is completely shutdown and restart the server.>
<31/05/2012 4:32:16 PM EST> <Notice> <WebLogicServer> <BEA-000365> <Server state changed to FAILED>
<31/05/2012 4:32:16 PM EST> <Error> <WebLogicServer> <BEA-000383> <A critical service failed. The server will shut itself down>
<31/05/2012 4:32:16 PM EST> <Notice> <WebLogicServer> <BEA-000365> <Server state changed to FORCE_SHUTTING_DOWN>

Root Cause: Some time even after proper shutdown or forceful shutdown .lok file does not get removed automatically and when users try to restart the server again and since file is already present it server fails to start the servers.
Solutions: Navigate to Idapfiles location under server and delete the “EmbeddedLDAP.lok” file from there, location would be e.g. /hta/home/fusion/osb_home/osb_install1/user_projects/domains/vhaosb-dev2/servers/AdminServer/data/ldap/ldapfiles and restart the Weblogic Server.

Err: The persistent store "_WLS_AdminServer" could not be deployed: <01/06/2012 10:56:47 AM EST> <Error> <Store> <BEA-280061> <The persistent store "_WLS_AdminServer" could not be deployed: weblogic.store.PersistentStoreException: [Store:280105]The persistent file store "_WLS_AdminServer" cannot open file _WLS_ADMINSERVER000000.DAT.
weblogic.store.PersistentStoreException: [Store:280105]The persistent file store "_WLS_AdminServer" cannot open file _WLS_ADMINSERVER000000.DAT.
                at weblogic.store.io.file.Heap.open(Heap.java:312)
                at weblogic.store.io.file.FileStoreIO.open(FileStoreIO.java:104)
                at weblogic.store.internal.PersistentStoreImpl.recoverStoreConnections(PersistentStoreImpl.java:413)
                at weblogic.store.internal.PersistentStoreImpl.open(PersistentStoreImpl.java:404)
                at weblogic.store.admin.AdminHandler.activate(AdminHandler.java:126)
                Truncated. see log file for complete stacktrace
<01/06/2012 10:56:47 AM EST> <Critical> <WebLogicServer> <BEA-000362> <Server failed. Reason:

Root Cause: Above error comes mostly when weblogic does not able to read the file store .DAT file. This file weblogic uses for its internal working. There are 7 weblogic sub systems which write information in this file e.g. Diagnostic Service, JMS Messages, JTA Transaction Log (TLOG), Web Services, EJB Timer Services, Store-and-Forward (SAF) Service Agents and Path Service. Also this file could be corrupted as well during forceful shutdown when users use kill -9 command, or reason can be anything else as well.
Solution:

cd $DomainHome/servers/AdminServer/data/store
find . –name *.DAT
Verify the file name in your result and error message should be same.
Rename this file and move from this directory to some other directory.
find "EmbeddedLDAP.lok" and "AdminServer.lok" as well and remove the same.
check the port using netstat –an | grep <Weblogic server port>, there should not be any open connection to this port.
Start your weblogic server either via weblogic script or node manner.

Note: .DAT file is very important file, and contains business data as well in Production system. Please take a backup of this file before doing any operation on it, so that later this file can be analysed to complete those transaction.

ERR: The loading of OPSS java security policy provider failed due to exception: <Jun 5, 2012 1:37:53 PM EST> <Critical> <WebLogicServer> <BEA-000386> <Server subsystem failed. Reason: weblogic.security.SecurityInitializationException: The loading of OPSS java security policy provider failed due to exception, see the exception stack trace or the server log file for root cause. If still see no obvious cause, enable the debug flag -Djava.security.debug=jpspolicy to get more information. Error message: JPS-02592: Failed to push ldap config data to libOvd for service instance "idstore.ldap" in JPS context "default", cause: org.xml.sax.SAXException: Error Parsing at line #1: 1.
org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1; <Line 1, Column 1>: XML-20108: (Fatal Error) Start of root element expected.

Root Cause: I need to find out exact root cause of this problem. As of now I am not quoting any details for why this error came but the solution which I have followed I am specifying here -
Solution:

delete “tmp” folder from the location $Domain\servers/AdminServer.
find out all the .lok file and .DAT file and delete it.
Find <location up to $Domain/servers/AdminServer> –name *.lok
Find <location up to $Domain/servers/AdminServer> -name *.DAT
Use the “rm” command to delete the files which comes as part of above find result.
Restart the Weblogic server.

ERR: EmbeddedLDAP java.lang.ArrayIndexOutOfBoundsException
During Admin server restart we were getting below error continuously and Admin server was not coming up-
####<Nov 5, 2012 4:47:05 AM EST> <Critical> <EmbeddedLDAP> <vans075007> <AdminServer> <VDE Replication Thread> <<anonymous>> <> <> <1352051225634> <BEA-000000> <java.lang.ArrayIndexOutOfBoundsException: 0

Root Cause: This Error comes when the changelog.data and changelog.index file get corrupted located in servers/Adminserver/data/ldap/ldapfiles .
Below are list of scenarios during when these file can get corrupted.
While the admin server was writing an LDAP entry to the changelog, it was interrupted by a forced shutdown, which made the changelog partially updated.
When the admin server rebooted, it attempted to process the changelog (i.e., send the entries to the managed servers), but encountered the partially updated changelog.
The partial update was an entry that had been assigned a change number, but there was no data for the entry. When the change log writer is interrupted between the index update and the data update and this update is in a synchronized method.
Solution: This Error comes when the changelog.data and changelog.index file get corrupted located in servers/Adminserver/data/ldap/ldapfiles .
Please take a backup of existing “ldap” folder deleted these two files, and restart the Admin servers. Both files will be created again and server will start successfully.
The changelog.data file is used in WebLogic Server (WLS) to store LDAP information regarding users, groups, roles and policies. The EmbeddedLDAP server has an index file and a data file. Each entry in the data file is pointed to by a index file entry; the index file entry is dictated by an integer that identified the entry.
For more details about issue and solution please refer the Oracle Note: DOC ID: 1325978.1, Following is list of general action which we can perfom in Test enviornment to fix the server startup problem:

Try to delete all the .lok file
Try to delete .DAT file insider $Domain/servers/AdminSever/step.
Take a backup of "tmp" folder inside servers folder and delete “tmp” folder
Take a backup of "data" foler inside servers folder and delete “data” folder
Change the port number if some port is already in use.

To be continued ...