Question: My current situation is:

* One hard disk
* Dual boot Ubuntu 11.04 and Windows 7. Partitions:
	+ 100MB Windows System thingy
	+ 144GB Main Windows
	+ 160GB Ubuntu
	+ 4GB Swap
	+ 12GB System Restore stuff

Now I want to install an 80GB SSD and move Ubuntu to it. AFAIK I need to:

* Shrink the 160GB Ubuntu partition to 80GB
* Copy it over to the SSD
* Change `fstab` to mount the SSD as `/`

How do I do the second? And what do I need to do about Grub?

Answer: 
I was able to do this migration successfully thanks to @psusi's instructions, however I observed one "gotcha."

After installing Grub on the new SSD, it still wouldn't boot - it was looking for the ramdisk image using the UUID of my old OS drive, which I had removed. Using the --recheck option fixed this:

```
$ grub-install --recheck /dev/ssd

```

This encourages grub to re-scan the BIOS, identify the new drive, and presumably use its UUID when passing the "root=" parameter to the kernel.
I tried to install `Boot-Repair` tool from instruction in the [answer](https://askubuntu.com/a/40454/1548713) of this question on Ubuntu 20.04 (on installed version, not live) to check that everything will be fine on live version:

```
sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt-get update
sudo apt-get install -y boot-repair && boot-repair

```

There was error:

> 
> Cannot add PPA: 'ppa:~yannubuntu/ubuntu/boot-repair'. ERROR:
> '~yannubuntu' user or team does not exist.
> 
> 
> 

Instruction from [here](https://askubuntu.com/a/226064/1548713) helped to me.

Below this instruction (How to install the Boot-Repair tool in an Ubuntu live disc):

```
sudo apt install software-properties-common; \
sudo add-apt-repository "deb http://archive.ubuntu.com/ubuntu $(lsb_release -sc) universe"; \
sudo add-apt-repository -y ppa:yannubuntu/boot-repair; \
sudo apt-get update; \
sudo apt-get install -y boot-repair && boot-repair

```

When command:

```
sudo add-apt-repository "deb http://archive.ubuntu.com/ubuntu $(lsb_release -sc) universe"

```

was being executed there was the following warning:

> 
> W: GPG error: <http://ppa.launchpad.net/yannubuntu/boot-repair/ubuntu>
> focal InRelease: The following signatures couldn't be verified because
> the public key is not available: NO\_PUBKEY 32B18A1260D8DA0B E: The
> repository 'http://ppa.launchpad.net/yannubuntu/boot-repair/ubuntu
> focal InRelease' is not signed. N: Updating from such a repository
> can't be done securely, and is therefore disabled by default. N: See
> apt-secure(8) manpage for repository creation and user configuration
> details.
> 
> 
> 

But it did not prevent installation of `boot-repair`. It was installed successfully.