Uly.me

cloud engineer

disk

GCP Find Instance Boot Disk

How to find a boot disk from an instance.

gcloud compute instances describe servername \
--format='get(disks[0].source)' \
--zone=us-central1-c \
--project project-id

Result

https://www.googleapis.com/compute/v1/projects/project-id/zones/us-central1-f/disks/servername-boot

GCP Keep Disk

Keep your disks when a VM is deleted.

gcloud compute instances set-disk-auto-delete server --no-auto-delete --disk=server-disk-1
gcloud compute instances set-disk-auto-delete server --no-auto-delete --disk=server-disk-2

To delete.

gcloud compute instances set-disk-auto-delete server --auto-delete --disk=server-disk-1
gcloud compute instances set-disk-auto-delete server --auto-delete --disk=server-disk-2

AWS Copy Snapshot to another Region

If you need to copy a snapshot from one region to another, here’s the AWS CLI command.

aws ec2 copy-snapshot \
    --region us-east-1 \
    --source-region us-east-2 \
    --source-snapshot-id snap-xxxxxxxxxxxxxxxxx \
    --description "This is the DR snapshot copy"

Output:

{
    "SnapshotId": "snap-xxxxxxxxxxxxxxxxx"
}

iotop

iotop is a Linux command similar to top but instead of CPU and memory it will display and monitor your disk IO usage.

To install, run the following command based on your Linux ditro.

yum install iotop
apt install iotop
dnf install iotop

To use.

iotop
iotop -o

Output:

GCP UEFI Compatible

When trying to boot from a disk created from snapshot and you’re getting an “UEFI feature is not available for this project” error, you’ll need to create a boot image with the –guest-os-features option set to “UEFI_COMPATIBLE.”

gcloud compute disks create new-server-disk-2 \
--project=project-name \
--source-snapshot=server-disk-2 \
--zone=us-central1-b \
--guest-os-features="UEFI_COMPATIBLE"

It’s about enabling guest operating system features on custom images. The guest operating system features let you configure networking, security, storage, and operating system options on custom images to be used on boot disks.

GCP Create Instance From Snapshot

There are two steps in creating an instance from a snapshot.

  1. Create a disk from snapshot
  2. Create an instance from the disk

Create a disk from snapshot.

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

Create an instance from disk.

gcloud beta compute instances create hostname \
--project=project-id \
--zone=us-central1-a \
--subnet=your-subnetwork \
--machine-type=n1-standard-1 \
--no-address \
--maintenance-policy=MIGRATE \
--service-account=service.account@developer.gserviceaccount.com \
--disk=name=instance-1,device-name=instance-1,mode=rw,boot=yes,auto-delete=yes \
--reservation-affinity=any \
--labels=builtby=john.doe \
--tags=web \
--scopes= \
--metadata=

GCP Convert Standard to SSD

How to convert Persistent Standard disk to SSD.

First create a snapshot of the disk.

gcloud compute disks snapshot your-server \
--snapshot-names manual-snapshot-disk-1 \
--project your-project \
--zone us-central1-c

Restore snapshot to SSD format.

gcloud compute disks create disk-1-ssd \
--source-snapshot manual-snapshot-disk-1 \
--project your-project \
--zone us-central1-a \
--type pd-ssd \
--size 10GB

Swap disks using GCP attach and detach.

Chroot A Boot Disk

Here’s a quick way to chroot another boot disk. Attach the rescued boot disk first. Run lsblk and mount. 

lsblk
mount -t xfs -o nouuid /dev/xvdf2 /mnt
mount --bind /proc /mnt/proc
mount --bind /sys /mnt/sys
mount --bind /dev /mnt/dev
chroot /mnt
cd /mnt
exit

Unmount when done.

umount /mnt/proc
umount /mnt/dev
umount /mnt/sys
umount /mnt