Posts Tagged ‘Windows’

Grub – Error 21: Selected disk does not exist

Posted in Technical on November 21st, 2011 by iyoung – 1 Comment

If you are creating a dual boot system, Windows and Linux you might run into this problem as I have just done when installing CentOS 6. When you first re-boot to go back into Windows and select “Other” from the Grub loader menu you are presented with “Error 21: Selected disk does not exist”. Almost as uninformative as it is annoying, but it can be fixed at least in my case by the following: -

Log into Linux, and run the following as root: -

vi /boot/grub/menu.lst

You’ll see something like: -

# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd0,0)
# kernel /vmlinuz-version ro root=/dev/VolGroup00/LogVol00
# initrd /initrd-version.img
#boot=/dev/hda
default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title CentOS (2.6.18-53.1.4.el5)
root (hd0,1)
kernel /vmlinuz-2.6.18-53.1.4.el5 ro root=/dev/VolGroup00/LogVol00 rhgb quiet
initrd /initrd-2.6.18-53.1.4.el5.img
title other
rootnoverify (hd1,4)
chainloader+1

What I had to do was change the last (hd1,4) to (hd0,0) then I changed the title to Windows instead of other. I also set the default to 1 so it defaults to windows and increased the timeout to 20.

This link was also very handy during the process of setting up http://www.techotopia.com/index.php/Installing_CentOS_with_Windows_in_Dual_Boot_Environment#Choosing_an_Operating_System_at_Boot_Time


MD5 Checksums and Windows

Posted in Technical on December 8th, 2009 by iyoung – Be the first to comment

Ever downloaded an application realised the site had the MD5 Checksums there but you didn’t bother to check them because you couldn’t be bothered to install something and faff just to generate MD5 hashes on Windows?

In case you are not familiar with MD5 Checksums, it is basically a number which represents the exact contents of the file, a finger print as it were, often when you download an application a website will provide the checksums and you ideally need to check your downloaded file matches. This ensures that what is about to be run is what the site had intended for you to have and nothing else had been added or removed.So anyway, I found a really nice easy and free little program to do such checks at the click of a mouse and thought I would share it.

http://www.colonywest.us/index.php?option=com_content&view=article&id=46&Itemid=56