Xen is the open source virtualization solution .This blog is about installing a new Xen server on Ubuntu 10.04. Also I have the composite window manager on top of the Xen! With full 3D support! To achieve this I do: 1- Install your Ubuntu Desktop 10.4 and upgrade your system; 1.1 – Install some packages: Read More…
Administering the Kerberos Database
April 3rd, 2011 by Manoj Chauhan View Comments »Configuring a Kerberos 5 Server To configure a basic Kerberos server, follow these steps: 1. Be sure that you have clock synchronization and DNS working on your server before configuring Kerberos 5. Pay particular attention to time synchronization between the Kerberos server and its various clients. If the server and client clocks are different by Read More…
What is the Oracle voting disk used for?
March 27th, 2011 by Manoj Chauhan View Comments »A voting disk is a backup communications mechanism that allows CSS daemons to negotiate which subcluster will survive. These voting disks keep a status of who is currently alive and counts votes in case of a cluster reconfiguration. It works as follows: a) Ensures that you cannot join the cluster if you cannot access the Read More…
How do I configure raw devices in order to install 10g Clusterware on RHEL5 or OEL5?
March 27th, 2011 by Manoj Chauhan View Comments »The raw devices OS support scripts like /etc/sysconfig/rawdevices are not shipped on RHEL5 or OEL5, this is because raw devices are being deprecated on Linux. This means that in order to install 10g Clusterware you’d have to manually bind the raw devices to the block devices for the OCR and voting disks so that the Read More…
Is the hangcheck timer still needed with Oracle RAC 10g and 11g?
March 27th, 2011 by Manoj Chauhan View Comments »YES! The hangcheck-timer module monitors the Linux kernel for extended operating system hangs that could affect the reliability of the RAC node ( I/O fencing) and cause database corruption. To verify the hangcheck-timer module is running on every node: as root user: /sbin/lsmod | grep hangcheck If the hangcheck-timer module is not listed enter the Read More…
Disk i/o & Performance Tuning Benchmarking Tool
March 25th, 2011 by Manoj Chauhan View Comments »Disk i/o & Performance Tuning Benchmarking Tool Dstat is a flexible replacement for vmstat, iostat, netstat and ifstat. Dstat overcomes some of their limitations and adds some extra features. Dstat is handy for monitoring systems during performance tuning tests, disk i/o, benchmarks or troubleshooting. Dstat allows you to view all of your system resources in Read More…
Domain Catchall in postfix
March 23rd, 2011 by Pawan Kumar View Comments »Hi, If you want to set up an account “user@abc.org” to catch all any mail not delivered to existing users in the domain “abc.org”, you can configure the account as a domain catchall. If the users “admin@abc.org”, “webmaster@abc.org”, and “nobody@abc.org” don’t exist, and mail arrives for them, it will be delivered to the catchall account Read More…
Monitoring Incoming & outgoing mails
March 23rd, 2011 by Pawan Kumar View Comments »Postfix V2.1 supports a “sender_bcc_maps” and “recipient_bcc_maps” functions. If you are using postfix then use following steps :- [root@map007]# vi /etc/postfix/main.cf Add following line to get a bcc copy to your email id when some one send a mail :- sender_bcc_maps = hash:/etc/sender_bcc Add following line to get a bcc copy to your email id Read More…
Zero-Downtime Restarts of backend servers with HAProxy
March 20th, 2011 by Manoj Chauhan View Comments »Zero-Downtime with HAProxy Putting up a maintenance page while you are doing an update and restarting your application servers is good practice, but it definitely hurts the user experience. setup a html page and check url – e.g. /haproxy_check.html. It will check the haproxy_check.html every 2 seconds and check the string OK inside the the Read More…
Using pipe in Varnish
March 15th, 2011 by Manoj Chauhan View Comments »Using pipe In most cases, the pipe action is not used for anything. However, if you want to stream objects, particularly large ones like videos, big zip files, you can use pipe. Using pipe means Varnish stops inspecting each request and just shuffles bytes to the backend. This can lead to multiple failure modes, from Read More…
Some examples of using LINUX/UNIX find command
March 13th, 2011 by Manoj Chauhan View Comments »Introduction The find command allows the Linux/Unix users to process a set of files and/or directories in a file subtree. You can specify the following: * where to search (pathname) * what type of file to search for (-type: directories, data files, links) * how to process the files (-exec: run a process against a Read More…
Backend Declarations in Varnish
March 12th, 2011 by Manoj Chauhan View Comments »A backend declaration creates and initializes a named backend object: backend www { .host = “www.manoj.com”; .port = “http”; } The backend object can later be used to select a backend at request time: if (req.http.host ~ “^(www.)?manoj.com$”) { set req.backend = www; } The timeout parameters can be overridden in the backend declaration. The Read More…
SMTP authentication using Mysql
March 10th, 2011 by Pawan Kumar View Comments »There are times when you need to have users authenticate their SMTP sessions. Perhaps you have roaming users and you don’t want to be an open relay, but you cannot predict where these users are. You need a way for them to say to your SMTP server “hey I belong here, let me send email”. Read More…
How to Export A MySQL Multiples Databases Structures Only
March 10th, 2011 by Manoj Chauhan View Comments »If you no longer need the data inside the database’s tables (unlikely), simply add –no-data switch to export only the tables’ structures. mysqldump –no-data -u root -p –databases db1 db2 db3 db3 db4 > /tmp/mysql_backup.txt
Install MySQL 5.5 on Ubuntu
March 8th, 2011 by Manoj Chauhan View Comments »I followed the steps on this page to install MySQL 5.5 on Ubuntu. To install and use a MySQL binary distribution, the basic command sequence looks like this: shell> groupadd mysql shell> useradd -r -g mysql mysql shell> cd /usr/local shell> tar zxvf /path/to/mysql-VERSION-OS.tar.gz shell> ln -s full-path-to-mysql-VERSION-OS mysql shell> cd mysql shell> chown -R Read More…
