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disks

GCP Identify Your Disks

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Here’s how to identify your disks on the system to cross check with GCP Dashboard.

ls -l /dev/disk/by-id

Result:

[root@servername ~]# ls -l /dev/disk/by-id
total 0
lrwxrwxrwx. 1 root root  9 Sep 15 05:30 google-boot -> ../../sda
lrwxrwxrwx. 1 root root 10 Sep 15 05:30 google-boot-part1 -> ../../sda1
lrwxrwxrwx. 1 root root  9 Sep 15 05:30 google-persistent-disk-1 -> ../../sdb
lrwxrwxrwx. 1 root root  9 Sep 15 05:30 scsi-0Google_PersistentDisk_boot -> ../../sda
lrwxrwxrwx. 1 root root 10 Sep 15 05:30 scsi-0Google_PersistentDisk_boot-part1 -> ../../sda1
lrwxrwxrwx. 1 root root  9 Sep 15 05:30 scsi-0Google_PersistentDisk_persistent-disk-1 -> ../../sdb

GCP Disks Attach To An Instance

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Here’s how to display a list the disks attached to an instance.

gcloud compute instances describe instance-name \
--project project-id \
--zone us-central1-c \
--format='yaml(disks[].source)'

Extend Regional Persistent Disks

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Here’s the command to extend your regional persistent disks.

gcloud compute disks resize disk-name \
--size 100 \
--project project-id \
--region us-central1

Or you can specify by zone.

gcloud compute disks resize disk-name \
--size 100 \
--project project-id \
--zone us-central1-c

Display the updated disk details.

gcloud compute disks list \
--filter="name=disk-name" \
--project project-id

Although you’ve increased disk size, the file system doesn’t know the extra space. Run this (for XFS).

xfs_growfs /dev/sdb

GCP Move Instance to Another Project

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Here’s how to copy a disk from one project to another.

gcloud compute disks create lamp-server \
--source-snapshot https://www.googleapis.com/compute/v1/projects/project-id/global/snapshots/lamp-server \
--project next-project-id \
--zone us-central1-a

Once all the disks are copied. You can create a snapshot of the boot.

gcloud compute disks snapshot lamp-server

Create an instance from snapshot.

gcloud compute disks create "hostname-boot" \
--project "project-id" \
--zone "us-central1-a" \
--source-snapshot "snapshot-name" \
--type "pd-standard" \
--size "100"

GCP Restore

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How to restore from GCP Snapshots. Let’s say you have an instance called webserver with 2 disks.

Restore from snapshots:

gcloud compute disks create webserver-boot-r \
--project=your-project \
--source-snapshot=webserver-boot-190616 \
--zone=us-central1-a
gcloud compute disks create webserver-data-r \
--project=your-project \
--source-snapshot=webserver-data-190616 \
--zone=us-central1-a

Stop instance. Detach and attach disks:

gcloud compute instances detach-disk webserver --disk=webserver-boot --zone us-central1-a
gcloud compute instances attach-disk webserver --disk=webserver-boot-r --zone us-central1-a --boot
gcloud compute instances detach-disk webserver --disk=webserver-data --zone us-central1-a
gcloud compute instances attach-disk webserver --disk=webserver-data-r --zone us-central1-a

Boot instance.

GCP Attach Detach Disks

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Google Cloud Platform just recently released a beta feature called detaching and attaching boot disks. Previously, boot disks were permanently attached to their VM instances. Now you have the ability to detach boot disk from your instance and attach it to another instance without deleting the original instance. You can also replace the boot disks for an instance rather than recreating the entire instance. I’ve tested it on my test account, and it works quite nicely.

I have 2 servers called blue-server and red-server. I’m detaching the disks on blue-server and attaching it to the red-server.

gcloud compute instances detach-disk blue-server --disk=blue-server-disk --zone us-central1-c
gcloud compute instances attach-disk cyan-server --disk=blue-server-disk --zone us-central1-c
gcloud compute instances detach-disk cyan-server --disk=blue-server-disk --zone us-central1-c
gcloud compute instances attach-disk blue-server --disk=blue-server-disk --zone us-central1-c

Results:

GCP: Attach and Detach Disks

This new GCP feature is still beta. There might be a few quirks here and there, but overall, it’s a must have feature if you are managing OS.