Have you ever found the need to keep all the thousands of files which you use in a single file.
On Linux there is a way to do that.So essentailly you can have a virtual drive in a file which has an entire filesystem.
And to Linux it does not appear any different then an ext3 on a actual physical hard drive or a partition.
The implications of this are very huge, so for example you want to share some data with any one which has hundreds of files etc or you want to just backup your entire filesystem.
Here is how to achieve this

dd if=/dev/zero of=mydatafile bs=1 count=1 seek=1M

Will create a file of one megabyte in size, but with only one byte 
actually stored on disk.

The convert that file into a ext3 partition by issuing the following command

mkfs.ext3 mydatafile

It will give a warning,say yes and let it proceed.
 
mke2fs 1.40-WIP (14-Nov-2006)
sparse-file is not a block special device.
Proceed anyway? (y,n) y

Then you can just mount the file as a filesystem/partition anywhere with the following command

mount -t ext3 -o loop mnt/mnt_point  mydatafile

Now you can just do anything in the /mnt/mnt_point and then you can even move it to another machine 1 single file and you have all your data there.

posted at: 23:03 | category: /linux | permanent link to this entry

This document outlines how to use G4L(ghost for linux) with knoppix.

Disclaimer :- Please use this document carefully and with your own responsibility.I cannot be handled responsible for any data loss corruption or damage of any sort.By referring to this doc you own complete responsibility of your actions.In case of doubt of liability/responsibility pls do not use this website.

Problem Description

1.  You want clone a hard drive especially in cases like you bought a bigger hard drive and you want to migrate your old data as well as settings etc from one machine to another machine.
to proprietary solutions like Norton Ghost.
2. You are looking for a solution which is platform/OS/filesystem  independent
3. You are looking for a bit-by-bit cloner of hard drive..

Existing alternatives and shortcomings
As always  people have thought about the above problem description and  found various kinds of solutions with varying level of success in different environment/scenarios.

• Alternative 1 : g4u 
• Pros - Very light weight , fits on a floppy or a USB drive and on CD.Hard Drive to be cloned can hold any type of filesystem including ntfs/fat etc.Since it is a bit by bit copy it does not matter what OS/filesystem is on the hard drive.
• Cons - Since it is so small it obiviously cannot fit all the drivers required for accessing all the different harddrives/network cards and also is very very weak in auto-detection of hardware.If it cannot detect your hardrive obviously it cannot clone it.Since it is bit-by-bit copy of the harddrive the image is a little bigger then other alternatives and it is slower also , but this can be overcome to some extent.
• Alternative 2 :  g4l bootable ISO
• Pros - Lightweight can fit on a small USB drive or on a mini-CD disc.Hard Drive to be cloned can hold any type of filesystem including ntfs/fat etc.Since it is a bit by bit copy it does not matter what OS/filesystem is on the hard drive.
• Cons - Hardware/Network card detection is very weak compared to Knoppix.If it cannot detect your hardrive obviously it cannot clone it.Since it is bit-by-bit copy of the harddrive the image is a little bigger then other alternatives and it is slower also , but this can be overcome to some extent.
• Alternative 3 :  Partimage
• Pros - Works on partitions as opposed to entire drives.So the image created by partimage of the partition is smaller as it is intimately aware about the filesystem on the partition.
• Cons - Ironically the Pros of partimage are its Cons also because it cannot create an image of filesystems it which it does not support.You will be responsible for manually creating partition tables / MBR etc.Currently it does not work on LVM.

G4L and Knoppix
Using G4L along with Knoppix solves one of its important shortcomings of auto-hardware detection.Knoppix is one of the best live-CD's with a very very good automatic hardware detection.
Another advantage of using it with Knoppix is that a lot of folks already have Knoppix CD/DVD which they use as their swiss knife and this script fits very well in the arsenal without having to install anything.

How-to use G4L with Knoppix
Here is a list of software which you will need

1. Knoppix live CD or DVD : Download the ISO from http://knoppix.net/get.php
2. Download source code(it is just shell script) of g4l from http://sourceforge.net/projects/g4l/

Step-By-Step Instructions(Steps look long as they are detailed but the whole process will not take a long time)

1. Boot with knoppix CD on the machine which has the hard drive to be cloned/backed up/restored
2. On the command prompt of knoppix do "su"
3. Goto to the /tmp folder by typing "cd /tmp" as root
4. Make a directory named g4l by typing in "mkdir g4l"
5. Download g4l sources from sourceforge.net using wget into the g4l directory created in step 4> like "wget http://easynews.dl.sourceforge.net/sourceforge/g4l/files3.tar.gz"
   
6. In step 4> I have used the v0.21 as the source , you can use whichever is the latest version.
7. Untar the files by issuing the following command "tar -zxvf  files3.tar.gz" into the /tmp/g4l folder
   
8. Now add the path of jetcat-mod to the path variable by typing  "export PATH=$PATH:/tmp/g4l/"
9. Now go back to the folder which has the g4l scripts by typing "cd /tmp/g4l/"
10. Now you are ready to run the g4l scripts , so just type in ./g4l.
11. Now you are all set and if everything goes well you can start cloning hard drives and use the functionality of G4L in knoppix.
12. Since g4l is a bit by bit copier of hard drives , in order to achieve better compression it is highly recommended that you follow the steps on http://fbim.fh-regensburg.de/~feyrer/g4u/#shrinkimg otherwise the image creation will be very slow and the files will be very very big.

Other Notes

1. You can copy the g4l scripts(just the scripts from the g4l/bootcd/rootfs/ ) and the jetcat executable to a usb stick and then just plop in the usb stick along with knoppix CD and then you dont have to download the files again
2. Since g4l needs ftp server you can always use the  ftp server which comes with knoppix.The docs are locaed here http://knoppix.net/wiki/FTP_FAQ
3. Once you have a local ftp server setup on knoppix you can also use a secondary hard drive to clone to the second hard drive which has a different geometry.Currently I do not know of a way in g4l to write the cloned image to a file.
4. If future versions of knoppix carry the G4L scripts and the jetcat executable , it will become very very easy.
5. The above instructions might also work for other Live-CD's as long as ncftp is already there on the lice-cd.

Other Alternatives

• I have moved to Truecrypt, you can read my review at Truecrypt Files on an encrypted Filesystem
• Wonders of 'dd' and 'netcat': Cloning OS harddrives
• WikiStartEn - Linbox Rescue Server - Trac
• Clonezilla

posted at: 15:44 | category: /linux | permanent link to this entry

You can power down unused hard drives by issuing the following command on a Linux box for IDE Drives Now when you say want to mount your drive and you issue a command like
Linux will automatically turn on the power of the hard drive and mount it.Though in some cases it will take a few seconds to power up.

posted at: 21:47 | category: /linux | permanent link to this entry

Over a period of time our photo/video collection doubles/triples/quadruples in ,multiple places on our hard drives and suddenly there is a need to clean up these duplicates.
FSLint is a free open source utility which you can use to do that on a Unix/Linux box.
You can read more about usage of this utility this on Linux Journal or on Linux.com

posted at: 01:49 | category: /linux | permanent link to this entry