Monthly Archives: August 2009

Reinstalling the Boot Loader on RHEL

In many cases, the GRUB boot loader can mistakenly be deleted, corrupted, or replaced by other operating systems.

The following steps detail the process on how GRUB is reinstalled on the master boot record:

  1. Boot the system from an installation boot medium.
  2. Type linux rescue at the installation boot prompt to enter the rescue environment site link.
  3. Type chroot /mnt/sysimage to mount the root partition.
  4. Type /sbin/grub-install /dev/hda to reinstall the GRUB boot loader, where /dev/hda is the boot partition.
  5. Review the /boot/grub/grub.conf file, as additional entries may be needed for GRUB to control additional operating systems.
  6. Reboot the system.

Cloud computing

Cloud computing is a style of computing in which dynamically scalable and often virtualized resources are provided as a service over the Internet.
Cloud computing can be confused with:

  1. grid computing—”a form of distributed computing whereby a ‘super and virtual computer’ is composed of a cluster of networked, loosely coupled computers, acting in concert to perform very large tasks”;
  2. utility computing—the “packaging of computing resources, such as computation and storage, as a metered service similar to a traditional public utility such as electricity”;
  3. autonomic computing—”computer systems capable of self-management”.

MySQL Table Maintenance.

This morning I was asked by one of the other Engineers in my group about an easy way to analyze all the tables in a database. So I pointed him to mysqlcheck. Which is a great command line client for performing table mainteneance on mysql database tables. It checks, repairs, optimizes, or analyzes tables, all from the command line. Like any other program it has a ton of flags, but here are three general ways to invoke it.

shell> mysqlcheck [options] db_name [tables]
shell> mysqlcheck [options] –databases db_name1 [db_name2 db_name3…]
shell> mysqlcheck [options] –all-databases

For more information check out.

MySQL 5.0 Reference Manual :: 4 MySQL Programs :: 4.5 MySQL Client Programs :: 4.5.3 mysqlcheck — A Table Maintenance Program

Unfreezing media in Netbackup on Solaris.

Here is something you don’t use everyday or at least I don’t. 🙂

First find the frozen media IDs.

shell>/usr/openv/netbackup/bin/goodies/available_media | grep FROZEN

A00060  HCART3   TLD      1       37     –       1     0        FROZEN
–snip–

Then unfreeze them with this command xenical otc.

shell> /usr/openv/netbackup/bin/admincmd/bpmedia -unfreeze -m A00060

Configuring YUM to use a Proxy Server.

There are two basic ways that you can configure YUM to use a proxy server.

First is by editing the yum.conf file pop over to this web-site. The yum.conf is usually localed in the /etc directory. You will need to add couple of parameters depending on your proxy configuration.

1.) The first parameter is to add the proxy server to the yum.conf.

# The proxy server – proxy server:port number
proxy=http://yum.proxy.server:3128

2.) Now If a username and password is required to login to the proxy server.

# The account details for yum connections
proxy_username=username
proxy_password=password

The second way is by configuring the user’s environmental variables.

1.) The first way is just by adding the proxy server information.

bash> http_proxy=”http://yum.proxy.server:3128″
bash> export http_proxy

2.) The second way is by adding the proxy server with an username and password.

bash> http_proxy=”http://username:password@yum.proxy.server:3128″
bash> export http_proxy