how to get & create partition size precisely?

**caljohnsmith** · January 27th, 2009

Anon0, how about first posting:

Code:

sudo fdisk -lu

And please identify the source partition and the destination drive.

**hyper_ch** · January 27th, 2009

Originally Posted by anon0

is that a disk-wide operation?

yes

Originally Posted by anon0

What if the source disk is larger than the target disk?

never tested... but if target is bigger it doesn't matter...

**anon0** · January 28th, 2009

Originally Posted by caljohnsmith

Anon0, how about first posting:

Code:

sudo fdisk -lu

And please identify the source partition and the destination drive.

Sure let's say source is /dev/sdb1 as follows:

Code:

Disk /dev/sdb: 120.0 GB, 120034123776 bytes
255 heads, 63 sectors/track, 14593 cylinders, total 234441648 sectors
Units = sectors of 1 * 512 = 512 bytes
Disk identifier: 0x2fee2fee
   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1       166015710   234436544    34210417+  fd  Linux raid autodetect

While target is /dev/sda as follows:

Code:

Disk /dev/sda: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders, total 156301488 sectors
Units = sectors of 1 * 512 = 512 bytes
Disk identifier: 0xe545ed40

**caljohnsmith** · January 28th, 2009

Do you want the destination partition to start at the beginning of the sda drive? I ask because the source partition sdb1 actually starts about 85 GB into the sdb drive. If you would like the destination partition to start at the beginning of the sda drive, how about doing:

Code:

echo '63,68420835,fd,*' | sudo sfdisk --no-reread -fuS /dev/sda -N1

That should create an unformatted partition on your sda drive exactly the same size as the sdb1 partition (about 34 GB). Then reboot, and post the new output of:

Code:

sudo fdisk -lu

And if that shows your new sda1 partition OK, you can copy the sdb1 partition to sda1 with:

Code:

sudo apt-get install dcfldd
sudo dcfldd if=/dev/sdb1 of=/dev/sda1 statusinterval=10 bs=10M conv=notrunc

Let me know how that goes or if you run into problems.

**anon0** · January 28th, 2009

thanks caljohnsmith. I actually tried parted again and got it to create the partition in the middle, just to test things out (it's interactive so it's less cryptic). This time it worked because last time I forgot a simple arithmetic: the end sector should be starting position + size of the source partition - 512 bytes, since the starting sector is a part of the partition. Also I noticed that 1GB=10^9 not 1024^3 here.