I really enjoyed the Qwiklabs – GCP Essentials – Creating a Persistent Disk lab, but I think Qwiklabs could extend the lab a bit further by showing how the disk is persistent by blowing  away a VM, starting a new one and reattaching the disk. So I decided to try it. You can follow the steps below  to do just that.

Start here after you’ve finished the “Creating a Persistent Disk” lab.

Let’s create a new folder on our  persistent disk. Run mkdir /mnt/mydisk   (while still SSH-ing to the VM)

Now add a file there with some text vi /mnt/mydisk/tmp/hello.txt

Press i  to switch to edit mode and type in some text (It was “Hi There!” in my case) then follow this sequence to save Esc : wq

It’s time to say goodbye to your VM and delete it.

In the Cloud Shell execute gcloud compute instances delete gcelab –zone=us-central1-c   and you will see something similar to the below

The following instances will be deleted. Any attached disks configured
 to be auto-deleted will be deleted unless they are attached to any
other instances or the `--keep-disks` flag is given and specifies them
 for keeping. Deleting a disk is irreversible and any data on the disk
 will be lost.
 - [gcelab] in [us-central1-c]

Do you want to continue (Y/n)?  y


Deleted [https://www.googleapis.com/compute/v1/projects/qwiklabs-gcp-678cde46183b8e95/zones/us-central1-c/instances/gcelab].

You can also go to the Cloud Console and verify that your “old” VM is gone.

Create a new VM (using Cloud Console or Shell) with the  name of gcelab2

When it is ready use the following command (in the Cloud Shell) to attach the disk:

gcloud compute instances attach-disk gcelab2 –disk mydisk –zone us-central1-c

SSH to the VM

Execute the below commands (similar to the ones you did as part of attaching the persistent disk to gcelab VM) necessary to create  a new mount point and mount the disk. DON’T run the  format (mkfs) command

sudo mkdir /mnt/mydisk
sudo mount -o discard,defaults /dev/disk/by-id/scsi-0Google_PersistentDisk_persisten
t-disk-1 /mnt/mydisk

You can run df -kh  to see the disk mounted and available

google245648_student@gcelab2:~$ df -kh
Filesystem      Size  Used Avail Use% Mounted on
udev            1.8G     0  1.8G   0% /dev
tmpfs           371M  7.5M  364M   2% /run
/dev/sda1       9.8G  983M  8.4G  11% /
tmpfs           1.9G     0  1.9G   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           1.9G     0  1.9G   0% /sys/fs/cgroup
/dev/sdb        196G   61M  186G   1% /mnt/mydisk

Don’t forget to check your message from the old VM

google245648_student@gcelab2:~$ cat /mnt/mydisk/tmp/hello.txt 
Hi There!