fstab operator error [solved]

lizardbrain · n00b Joined: 03 Jun 2007 Posts: 64 Location: the swamp

50 or so years ago, when I was a young electronics technician, we called it "operator error". Here's what I stupidly did:

During the install process, while editing fstab, I forgot to add a line to mount /dev/sda4 at /home. Since then I've installed a bunch of packages, some with looooong compile times. I'd rather not start the install process again (although I will if necessary). Is there some way for me to move all /home data from /dev/sda3 to /dev/sda4 without trashing the system? dd? gparted?

Thanx for any help and/or recommendations.

Man, do I feel stupid.

ferreirafm · Posted: Tue Mar 18, 2014 7:59 pm Post subject:

lizardbrain,
dd is likely to work but sda3 and sda4 partition should have strictly the same size. Otherwise I would use tar with ignore-failed-reads (see man).

lizardbrain · n00b Joined: 03 Jun 2007 Posts: 64 Location: the swamp

Thanks for your reply, ferreirafm.

I apologize if my tendency to ramble resulted in a lack of clarity in my post. I don't want to move /dev/sda3 data to /dev/sda4; I just want to move the data in /home to /dev/sda4 from its current location on /dev/sda3. I'd like to leave all other data on /dev/sda3 intact. Am I correct in assuming that /dev/sda3 must be mounted for this operation?

NeddySeagoon · Posted: Tue Mar 18, 2014 8:43 pm Post subject:

lizardbrain,

Log in as root, so /home is not in use.

Make a mountpoint /mnt/tmp and mount your home partition there.

ferreirafm · Posted: Tue Mar 18, 2014 8:50 pm Post subject:

lizardbrain,
dd requires unmounted partitions. However, from your second post, I would rather use tar. In this case, both partition should be mounted if you want to tar and copy at the same time. Otherwise, you may tar your data first if your source partition has enough space and mount your target partition and copy your tarfile afterwards.
Best.

NeddySeagoon · Posted: Tue Mar 18, 2014 9:00 pm Post subject:

ferreirafm,

dd doesn't care but if the partition you copy is in use, you will get an image of that in use filesystem.
The image will be made but it may not be any use to you.

cp -a, tar and rsync all work for the copy operation.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

lizardbrain · n00b Joined: 03 Jun 2007 Posts: 64 Location: the swamp

NeddySeagoon,

An elegant solution, and one that saves me much time and heartache. As I already use rsync -avz for backups and I'm comfortable with it, I think that's what I'll use for this. I may not get to it until tomorrow, but if I manage to accomplish it without further screwups I'll add a "solved" to the subject line.

Thank you very much.

ferreirafm, once again, thanks for your help, too.

ferreirafm · Posted: Wed Mar 19, 2014 1:13 pm Post subject:

krinn · Watchman Joined: 02 May 2003 Posts: 7470

ferreirafm · Posted: Wed Mar 19, 2014 2:08 pm Post subject:

Hi krinn,
I apologize other readers for this off-topic post and also lizardbrain for being so imprecise in my answers. I will be glad in remove my post if you judge necessary. I was just trying to help and learn a bit more.
Best.

lizardbrain · n00b Joined: 03 Jun 2007 Posts: 64 Location: the swamp

Success!

Once again the Gentoo community has come through for me. I would've given up on Gentoo years ago if not for the support I get here.

Thank you.

NeddySeagoon · Posted: Wed Mar 19, 2014 7:18 pm Post subject:

ferreirafm,

There are many ways to be right including your use of dd.
dd makes an image of the object passed to in by if= if thats a partition, you get a partition image, including all of the unallocated space.
Its not wrong, just inefficient.

krinn is exaggerating. I have been wrong and when I am I'm pleased to be called for it too.
In our community we all learn from one another, including me and krinn :).
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.