DiskDump to a smaller USB

DustinB3403

@MattSpeller How?

I have never used dd

MattSpeller

@DustinB3403 oh!! you're in for a treat!

It's practically the only linux thing I know how to do because it's damn useful

Let me find a guide here....

DustinB3403

So /dev/sdd has

sdd1 etc3 4GB
sdd2 fat32 4gb
sdd3 lvm2 pv 21.82GB

DustinB3403

Now I very well might need to restart the setup if in fact this USB is using almost 22GB on a partition that stores nothing..

MattSpeller

@DustinB3403 http://www.computerhope.com/unix/dd.htm

Examples at the bottom, you want to take a copy of the whole SDD drive and dump it to an image of whatever flavour you fancy.

DustinB3403

So

dd if=/dev/sdd of=/dev/sdb

Should clone it from the larger to the smaller disk?

MattSpeller

@DustinB3403 said:

So
dd if=/dev/sdd of=/dev/sdb
Should clone it from the larger to the smaller disk?

Uhhhh yeahhhhhhh but you don't want to do that like that

First you want someone to double check what I'm suggesting, then read on

Something like:

dd if=/dev/sdd of=/dev/(hard drive)/(backup folder)/imageof32gbimportantthingy.img bs=4k

will get you a backup copy of the 32gb, then you can mangle it with GParted and not worry

DD is the ultimate "I want to copy X to Y and don't bother me with the details" tool - it's INCREDIBLY powerful

DustinB3403

So I have to backup it up to an img file first and then write it, is that correct?

MattSpeller

@DustinB3403 said:

So I have to backup it up to an img file first and then write it, is that correct?

Back it up to the img file then consult with someone who knows more man. We're at the bleeding edge of my linux expertise here.

Were it me, I'd take the backup then resize the 32GB usb with gparted then you can use gparted or DD to copy it to the other USB

stacksofplates

There might be an easier way, but I would dd it to a logical volume, then shrink the logical volume and then dd the volume to the smaller USB.

lvcreate -L 32G -n <name> <volumegroup>

dd if=/dev/usbdrive of=/dev/<volumegroup>/<volumename> bs=4M

resize2fs /dev/<volumegroup>/<volumename> 16G

lvreduce -L 16G /dev/<volumegroup>/<volumename>

dd if=/dev/<volumegroup>/<volumename> of=/dev/smallerusbdrive

I would take a backup of the 32 GB usb drive before I did anything. You can just dd if=/dev/usbdrive of=/home/dustinb3403/usbfile bs=4M to make sure nothing is lost.

MattSpeller

@johnhooks said:

then shrink the logical volume

How?

Also, what do you mean by a logical volume?

Dashrender

@MattSpeller said:

@johnhooks said:

then shrink the logical volume

How?

Also, what do you mean by a logical volume?

A partition.

MattSpeller

@Dashrender Thank you, I'm going to get a coffee, I'm slow today.

stacksofplates

@MattSpeller said:

@johnhooks said:

then shrink the logical volume

How?

Also, what do you mean by a logical volume?

I updated my post to show how

MattSpeller

@johnhooks hero of the thread - thank you, I'm saving that to try at home!

stacksofplates

@MattSpeller said:

@johnhooks hero of the thread - thank you, I'm saving that to try at home!

Ha don't call me a hero until we are sure it works

And like I said, there might be an easier way to do this but that's the first I thought of.

stacksofplates

All of that is also assuming you have space left to make a logical volume. I always leave extra room for LVM snapshots and one off scenarios like this.

stacksofplates

One other thing to watch for. Resize2fs only works with ext file systems. Last I heard you can't shrink an XFS file system, only grow it.

stacksofplates

I thought of one other way that could possibly work also. You can just copy the MBR on the big USB to the small one to make it bootable with dd if=/dev/bigusb of=/dev/smallusb bs=512 count=1 then you can just copy the actual files from the big USB to a new partition on the small one.

JaredBusch

BUy a 32gb USB. They are < $20. How much time are you wasting on this?