How to Enable a DHCPv4 Client to Request a Specific Host Name

1. On the client system, edit the /etc/default/dhcpagent file as superuser.
2. Find the REQUEST_HOSTNAME keyword in the /etc/default/dhcpagent file and modify the keyword as follows:

   REQUEST_HOSTNAME=yes

   If a comment sign (#) is in front of REQUEST_HOSTNAME, remove the #. If the REQUEST_HOSTNAME keyword is not present, insert the keyword.
3. Edit the /etc/hostname.interface file on the client system to add the following line:inet hostnamehostname is the name that you want the client to use.
4. Type the following commands to have the client perform a full DHCP negotiation upon rebooting:

   # ifconfig interface dhcp release
   # reboot

   The DHCP data that is cached on the client is removed. The client restarts the protocol to request new configuration information, including a new host name. The DHCP server first makes sure that the host name is not in use by another system on the network. The server then assigns the host name to the client. If configured to do so, the DHCP server can update name services with the client's host name.

Root Password Recovery - Solaris 10 without using CD/DVD

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                  1. Bring the server at OK prompt

# init 0
2.Boot the system using new boot mode called Failsafe mode which is used to boot your server from RAM without any need of CD/DVD.

{0} ok boot -F failsafe

Starting shell.

# uname –a

SunOS 5.10 Generic_142909-17 sun4u sparc SUNW,Sun-Fire-V245

# df –k

Filesystem kbytes used avail capacity Mounted on
/ramdisk-root:a 201463 178943 2374 99% / ————> Server booted from RAM.
/devices 0 0 0 0% /devices
ctfs 0 0 0 0% /system/contract
proc 0 0 0 0% /proc
mnttab 0 0 0 0% /etc/mnttab
swap 7725248 320 7724928 1% /etc/svc/volatile
objfs 0 0 0 0% /system/object
sharefs 0 0 0 0% /etc/dfs/sharetab
swap 7725504 576 7724928 1% /tmp
/tmp/dev 7725504 576 7724928 1% /dev
fd 0 0 0 0% /dev/fd
#

How to turn Oracle RAC off/on?

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I’ve requirement from client to change their architecture. Migrating Oracle RAC to Single Instance. Then I found article related to this in order to successfully migrate Oracle RAC to Single Instance.
On 10R2 if the Oracle binaries are installed with the RAC, one can’t use those binaries to start Oracle Instance if CRS is not running, so in case when one needs to start the instance without CRS one needs to rebuild the oracle and it’s libraries to start the instance.
To turn off RAC
# link the oracle libraries
$ cd $ORACLE_HOME/rdbms/lib
$ make -f ins_rdbms.mk rac_off
# rebuild oracle
$ cd $ORACLE_HOME/bin
$ relink oracle
To turn on RAC
# link the oracle libraries
$ cd $ORACLE_HOME/rdbms/lib
$ make -f ins_rdbms.mk rac_on
# rebuild oracle
$ cd $ORACLE_HOME/bin
$ relink oracle
Reference : http://oraclespin.wordpress.com/

How to Increase swap size in Linux

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In Linux, as in most other Unix-like operating systems, it is common to use a whole partition of a hard disk for swapping. However, with the 2.6 Linux kernel, swap files are just as fast[7] as swap partitions, although Red Hat recommends using a swap partition. The administrative flexibility of swap files outweighs that of partitions; since modern high capacity hard drives can remap physical sectors, no partition is guaranteed to be contiguous. You can add swap file as a dedicated partition or use following instructions to create a swap file.
a) Login as the root user
b) Type following command to create 512MB swap file (1024 * 512MB = 524288 block size):
# dd if=/dev/zero of=/swapfile bs=1024 count=524288
c) Set up a Linux swap area:
# mkswap /swapfile
d) Activate /swapfile swap space immediately:
# swapon /swapfile
e) To activate /swapfile after Linux system reboot, add entry to /etc/fstab file. Open this file using text editor such as vi:
# vi /etc/fstab

How To: Clustering in GlassFish Version 2

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Version 2 of the GlassFish Java EE Application Server contains many new features, among them enhanced clustering capabilities. The new clustering capabilities enhance high availability and scalability for deployment architectures through in-memory session state replication. With in-memory state replication, clustered server instances replicate session state in a ring topology, storing the replicated information in memory.
This article describes the clustering capabilities of GlassFish version 2 and helps you get started deploying your application to a GlassFish cluster.
Sun Java System Application Server 9.1 is the Sun-supported distribution of the open-source GlassFish version 2 application server. This article uses the name GlassFish version 2 to embrace both of them.

Basic Concepts

Clusters in an application server enhance scalability and availability, which are related concepts.
In order to provide high availability of service, a software system must have the following capabilities:

• The system must be able to create and run multiple instances of service-providing entities. In the case of application servers, the service-providing entities are Java EE application server instances configured to run in a cluster, and the service is a deployed Java EE application.
   
• The system must be able to scale to larger deployments by adding application server instances to clusters in order to accept increasing service loads.
   
• If one application server instance in a cluster fails, it must be able to fail over to another server instance so that service is not interrupted. Although failure of a server instance or physical machine is likely to degrade overall quality of service, complete interruption of service is not acceptable in a high-availability environment.
   
• If a process makes changes to the state of a user's session, session state must be preserved across process restarts. The most straightforward mechanism is to maintain a reliable replica of session state so that, if a process aborts, session state can be recovered when the process is restarted. The principle is similar to that used in high-reliability RAID storage systems.

Taken together, these demands necessarily result in a system that sacrifices high efficiency to attain high availability.
In order to support the goals of scalability and high availability, the GlassFish application server provides the following server-side entities:

• Server Instance – A server instance is the Java EE server process (the GlassFish application server) that hosts your Java EE applications. As required by the Java EE specification, each server instance is configured for the various subsystems that it is expected to run.
   
• Node Agent – A node agent is an agent process that runs on every physical host where a server instance runs. The node agent manages the life cycle of a server instance when directed by the Domain Administration Server (DAS) described later in this article.
   
• Cluster – A cluster is a logical entity that determines the configuration of the server instances that make up the cluster. Usually, the configuration of a cluster implies that all the server instances within the cluster have homogeneous configuration. An administrator typically views the cluster as a single entity and uses the GlassFish Admin Console or a command-line interface (CLI) to manage the server instances in the cluster.

Node agents, server instances, and clusters can be created at GlassFish installation time, as described near the end of this article. Clusters and instances are organized into administrative domains, described below, that are characterized by the Domain Administration Server (DAS).

Domain Administration Architecture

Central to GlassFish clustering architecture is the concept of an administrative domain. The administrative domain is a representation of access rights for an administrator or group of administrators. The following figure shows an overview of the domain administration architecture, in the context of a single domain.

Figure 1. Domain Administration Architecture

Issue: Troubleshooting lost Virtual interfaces after system reboot

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Troubleshooting lost Virtual interfaces after system reboot Virtual network interface that has just been setup is not seen as configured after a system reboot. The virtual interface no longer shows up in the ifconfig  or netstat output.

Below steps explains the troubleshooting steps to diagnose and ensure that virtual interface is configured permanently.

Problem Symptoms:

1. can not ping virtual ip address
2. can not ping virtual hostname
3. system is not accessible via virtual IP address
4. no connection to system virutal IP/hostname
5. ifconfig return physical interfaces setup only
6. network configuration gone after system reboot

Troubleshooting each symptom :
Resolution 1. Verify the physical link level and network device media is working fine. Always check if there are any problem on network hardware level as the logical interfaces are always bound to the physical interface. As the virtual interface is dependent on the physical link and the network connect,  the virtual interfaces/hosts bound to the affect physical link will also be affected.  Please  refer to the following document to troubleshoot the physical link problems.
Resolutions 2. Verify the network driver is loaded and physical interfaces are plumbed up .

a. Check if driver module has been loaded properly.

# modinfo |grep hme

117 7bb6a000   f798   7   1  hme (10/100Mb Ethernet Driver v1.180)

b. Use the kstat and netstat commands to check driver kernel statistic and interface status.

For example:

# netstat -i

How To: Change IP Address in Solaris 10 without reboot

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Adding or editing the IP address on a Solaris 10 server is different from the previous versions of
the OS (Solaris 9, Solaris 8 etc).

In the previous versions of the Solaris Operating System, you need to edit the /etc/hosts file
and add/edit the entry for the IP address and the hostname.

Example:

192.168.1.1 sun1

However, in Solaris 10, you should edit the /etc/hosts file (a symlink to /etc/inet/hosts file) and
the /etc/inet/ipnodes file and add an entry for IP address and hostname.

Once done, restart the Network service using

# svcadm restart network/physical