Backup of disk using ddrescue

vijay_babu1981 · 10-27-2009, 03:47 AM

Hi

I plan to make a backup of my USB flash of size 8GB and copy the total contents on another 8GB flash.

I intend to use ddrescue for this purpose.

But I noticed that the destination disk is slightly smaller in size (may be 1 cylinder less). Can I still run ddrescue successfully or there is a chance of failure?

Regards

MensaWater · 10-28-2009, 08:03 AM

I haven't used ddrescue but its name implies it relies on dd. The dd command is doing a byte for byte copy without caring whether there is anything on a specific sector or not so I'd expect this to fail if the target was smaller than the source.

vijay_babu1981 · 10-28-2009, 08:25 AM

Quote:

Originally Posted by jlightner

I haven't used ddrescue but its name implies it relies on dd. The dd command is doing a byte for byte copy without caring whether there is anything on a specific sector or not so I'd expect this to fail if the target was smaller than the source.

Dear jlightner,

Thanks for the reply. I took the chance and ran the ddrescue using smaller destination disk.

It worked fine. I have fedora linux operating system installed on the source disk (not live). After making the copy, I am able to boot using the destination disk and have not seen any problems yet. I hope it will keep on working.

Regards

pokemaster · 11-18-2009, 10:50 AM

ddrescue is a separate tool, and only copies the necessary blocks. So long as you have no data on the "excess" space of your source drive, it will continue to work. You could shrink the FAT partition by a bit to make them the same size.

kdelover · 11-18-2009, 11:25 AM

there is a ubercool dd command tutorial check that out :-)

gabthetech · 05-31-2012, 02:39 PM

Hello, I have a question. I have a hard drive with some bad sectors, so I'm running DDRESCUE -d -f /dev/sda /dev/sdb...The two drives in question are both 40GB hard drives, but the source drive is 0.02GB larger than the destination drive. How do I tell DDRESCUE to truncate the data to fit onto the 40GB destination drive without failing. The fail message I get is "Write Error: No space left on device." I've actually already resized the partition on the source drive, leaving about 3-4GB of unused space, thinking that would be sufficient. But, it still returned the same error.

Thanks in advance,
Gabe

TobiSGD · 05-31-2012, 03:07 PM

Just ignore the error, I you have no data on the part it can't copy then no harm is done and it will work.

gabthetech · 05-31-2012, 04:07 PM

Quote:

Originally Posted by TobiSGD

Just ignore the error, I you have no data on the part it can't copy then no harm is done and it will work.

Thanks, I probably should have checked the partition table after the 2nd "fail", but I didn't cause I thought it had failed like the first one did.

Thanks for your help.