How to resize filesystem (image file)? how to truncate the image?

nikov3 · 06-26-2006, 03:12 AM

I have one image file that have linux ext2 fs and it is 20gb I want to resize it at 10gb
everybody tell me to create new image that is 10gb and to copy from 20gb image to 10gb but when I copy all and I boot fedora it tell me that fs have some new futures to get new e2fsck

How I can resize image other way I hear that I can user resize2fs but when I resize it image size is still 20gb I have to truncate it how to do that ?

blackhole54 · 06-26-2006, 09:13 AM

You can use the program parted (partition editor) to resize a partition. I don't know that it is safe to resize a partition you are currently using. But you can download (either floppy or CD) versions that have their own OS they boot into, so the partition you are modifying is not in use. Some live CDs, such as KNOPPIX also contain parted, and perhaps a graphical interface for it. There is always some danger in doing this sort of operation, so it is best if you have things backed up first.

Quote:

Originally Posted by nikov3

but when I copy all and I boot fedora it tell me that fs have some new futures to get new e2fsck

I don't understand what you mean. If this is still relevant to you, perhaps you could post the exact error message.

nikov3 · 06-26-2006, 10:42 AM

Quote:

Originally Posted by blackhole54

You can use the program parted (partition editor) to resize a partition. I don't know that it is safe to resize a partition you are currently using. But you can download (either floppy or CD) versions that have their own OS they boot into, so the partition you are modifying is not in use. Some live CDs, such as KNOPPIX also contain parted, and perhaps a graphical interface for it. There is always some danger in doing this sort of operation, so it is best if you have things backed up first.

I don't understand what you mean. If this is still relevant to you, perhaps you could post the exact error message.

I have uml and fedora is in one image file that is ext2 I need to resize it

blackhole54 · 06-26-2006, 08:03 PM

Quote:

Originally Posted by nikov3

I have uml and fedora is in one image file that is ext2 I need to resize it

I am not sure what "uml" is. You can resize your fedora partition using parted, but as I explained in my last post, you need to do so while fedora is not running. You can get a live CD or bootable floppy to do that. And it would be a good idea to back things up first, just in case something bad happens.

What I didn't understand was the error message you got when you tried to boot after copying fedora.

zeitounator · 06-27-2006, 03:02 AM

parted will not be of any help.... parted can resize a partition, not an image file.

When you say (in your first post) you tried to copy from one image file (the 20Gb one) to an other (the 10 Gb one), can you state exactly how you did this ? I see two alternative to acheive your goal. The first one is the fastest one but easy to screw-up. The second is a little longuer but almost errorprone.

--- 1 ---
Now that you have resized your file system with resize2fs, if you know exactly the block size on your image file and the number of blocks used by the remaining file system, just copy those blocks to a new image file (replace <bs>, <fsBlocks> by corresponding values).

Code:

dd if=/path/to/currentImg of=/path/to/newImg bs=<bs> count=<fsBlocks>

Once this is done, you can check your new image file

Code:

e2fsck /path/to/newImg

--- 2 ---
Copy the entire content from one fs to another

Create an empty 10Gb image file:

Code:

dd if=/dev/zero of=/path/to/newImgFile bs=1k count=10485760

Create an ext3 filesystem on the image:

Code:

mke2fs -j /path/to/newImgFile

When you get the warning about the file not being a block special file, just answer yes to proceed.

Mount the current image file and the new one

Code:

mount -o loop /path/to/currentImgFile /path/to/currentMntPoint
mount -o loop /path/to/newImgFile /path/to/newMntPoint

Copy all the content of the current filesystem to the new one preserving permissions

Code:

cd /path/to/currentMntPoint
tar cf - . | tar xfp - -C /path/to/newMntPoint

You can (as in solution 1) check your new image filesystem. DO NOT FORGET TO UNMOUNT FIRST.

Code:

umount /path/to/newMntPoint
e2fsck /path/to/newImgFile

-----
Good luck