The role of system administration involves three different responsibilities.

1. Be ready to Prevent the issues which are Expected to Arise

2. Be ready to Resolve the issues which are already Expected but couldn’t prevent from occurring.

3. Be Ready to Resolve the issues which are unexpected in nature.

We all are very well trained to fulfill the  first two responsibilities in most efficient manner. But, very few of us are actually ready to deal with the third responsibility, and the reason is not the technical capability but it is because of  ” lack of visibility on how our servers, that we are managing, are connected with other IT infrastructure components ( like networks / storage / power supply ) “.  In this post I am going  shed some light on this third responsibility of the system administrator.

The most unexpected and major outage for any IT infrastructure could happen due to the complete power supply failure in a Data center with some technical / human error. When the power supply fails, it is not only the servers that are going down but also the other major components, like network devices  and Storage devices, will also go down. You can look at the below figure to understand how the components in a data center are interconnected to each other. Full Story

This problem is not common to all the versions and releases but specific to the released of Solaris 8 and 9 ( I am not able to get those number clearly to mention here)

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If you want to make a TCP application bind to a different port instead of standard port then here is what you do.  This will enable to telnet to a machine only if you know the port number.

1. vi /etc/services file and edit the line for telnet

telnet          23/tcp

change this line to

telnet          12121/tcp

where 12121 is port number that it is going to listen for telnet requests.Make sure that you use port number bigger than 1k (1024 bytes) as the ports less than 1K are reserved ports.

2.  Kill inetd daemon and restart it or do HUP on it.

% ps -ef | grep inetd

% kill -HUP

3. Telnet to the client by specifying port number to connect to this machine.

% telnet hostname 12121

Below are the steps commonly followed for the most of the enterprise networks where the data center located remotely and support performs build procedures remotely.

1. Procuring Hardware

2.  Allocate DC space and Racking Hardware

3.  Allocating network ports

4.  Configuring remote consoles

5.  Gather System Basic information for remote installation

6.  Installing the operating system remotely using Jumpstart Full Story

There are three standard file descriptors:

• stdin 0 – Standard input to the program.
• stdout 1 – Standard output from the program.
• stderr 2 – Standard error output from the program.

Normally, input is from the keyboard or a file. Output, both stdout and stderr, normally goes to the terminal, but a user can redirect one or both of these to a file or multiple files. “2>&1″ means “take the standard error output from the program and send it to the same place that standard output is going”. In addition to file redirection symbols, there are a number of special symbols you can use at the command line.

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Follow these steps to:

• ensure dns client configuration is in place and enabled;
• verify mail exchanger lookups are successful (if using DNS for mail exchanger lookups).
• To resolve error conditions, consult your DNS or Sendmail administrator for proper configuration parameters for your environment.

Is system configured as a DNS client:

Solaris 8, 9 and 10:

/etc/nsswitch.conf  “hosts:” line contains “dns” keyword
/etc/resolv.conf exists with a minimum configuration of at least 2 (3 preferred) nameserver IP addresses

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