CloudPe — VM Rescue Mode

1. Overview

Rescue Mode lets you boot a virtual machine (VM) into a temporary rescue environment to troubleshoot and repair issues such as failed boots, corrupted file systems, lost SSH keys, or misconfigured settings — without deleting or destroying data. In rescue mode, your VM boots from a minimal rescue image while its original boot disk remains attached as a secondary volume for inspection and repair.

Typical use-cases include:

• Fixing boot loader issues
• Recovering or resetting SSH credentials
• Repairing file system corruption
• Correcting problematic network or configuration settings
• Copying data off an unstable VM

(This concept is similar to VM rescue functionality offered in other cloud platforms and infrastructure solutions.)

2. Prerequisites

Before starting rescue operations, ensure:

1. You have permission to manage the VM and access to the CloudPe dashboard or CLI.
2. The VM is currently in Running (Active) or Stopped state — rescue mode cannot be entered from transitional states.
3. A rescue image is available (Linux or Windows rescue ISO/template) in your CloudPe image repository.
4. You understand basic console and SSH access tooling to interact with rescue shells.

3. How Rescue Mode Works

When you put a VM into rescue mode:

• CloudPe stops the VM gracefully (if it’s running).
• The VM boots from a rescue image (minimal OS environment).
• The original boot volume is attached as a secondary disk (e.g., /dev/vdb).
• You can mount and inspect the original disk to perform repairs.

(The virtualization platform’s rescue mechanism functions similarly: the boot disk attaches as secondary and the rescue OS runs as primary.)

4. Entering Rescue Mode (CloudPe Dashboard)

1. Login to the CloudPe dashboard.
2. Navigate to Compute → Virtual Machines.
3. Select the affected VM from the list.
4. Click the ellipsis (···) or action menu.
5. Choose Rescue Mode (or Enter Rescue Mode).

1. In the dialog, select a rescue image (Linux/Windows compatible).

1. Confirm and click Start/Enter.

You will see the VM status change to Rescue.

Note: Use console or SSH access to connect once the rescue environment is ready.

5. Using Rescue Mode (Console/SSH)

A. Accessing the Console

• Launch the VM’s console from the CloudPe UI to interact directly.
• Use the provided root/admin credentials for the rescue image.

B. Mounting Original Disk

Once in rescue shell:

Linux example

# list disks
fdisk -l
OR
lsblk


# create mount point
mkdir /mnt/original

# mount original disk (example)
mount /dev/vdb1 /mnt/original

# inspect logs or fix files
cd /mnt/original

(Similar steps are used in other rescue environments such as OpenStack rescue guides.)

C. Resetting Passwords or Fixing Configs

• Edit /etc/ssh/sshd_config, reset SSH keys, fix /etc/fstab, etc.
• Run fsck for file system issues.

6. Exiting Rescue Mode

Once fixes are complete:

1. From the CloudPe dashboard, select the rescue VM.
2. Click Exit Rescue Mode (or Unrescue VM).
3. Confirm exit — CloudPe will reboot the VM normally.

The status will transition back to Active/Running.

7. Windows VM Considerations

Rescuing Windows VMs may require extra care:

• Ensure the rescue image provides Windows support.
• If original and rescue disks get conflicting identifiers, you may need to use Disk Management to change disk IDs so the Windows bootloader can find the system volume.

8. Troubleshooting Common Issues

VM Stuck or Fails to Enter Rescue Mode

• Ensure the VM is in a valid state (Active/Stopped).
• Confirm the rescue image exists and is compatible.
• Try a different rescue image.

Cannot Access Rescue Console

• Ensure firewall and security group rules allow console or SSH.
• Use browser console if SSH fails.

Original Disk Not Visible

• Confirm the disk attached as secondary (/dev/vdb or similar).
• If not attached, re-attach via CloudPe disk management UI or CLI.

VM Fails to Boot After Exit

• It may be due to unresolved boot loader configs.
• Re-enter rescue mode and verify boot files, or restore from backup.

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9. Best Practices

✅ Backup First: Always snapshot or backup your VM before entering rescue mode.
✅ Use Tested Rescue Images: Avoid corrupt or untrusted rescue images.
✅ Limit Duration: Only keep VMs in rescue mode while performing troubleshooting.
✅ Document Fixes: Keep a record of the actions performed for future reference.

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10. Related Operations

Operation	Purpose
Snapshot/Backup	Take a point-in-time copy of VM before rescue.
Volume Restore	Restore boot disks from backups if rescue fails. (CloudPe supports volume restore workflows.) CloudPe
Reset State	If VM stuck in error, CloudPe reset might help pre/post rescue.

🔗 Frequently Asked Questions (FAQ)

What login credentials should I use in rescue mode?

You can use the same username, password, or SSH keys as your original VM.
The rescue environment applies the same authentication settings as the original instance.

Note: Some rescue images (for example, Ubuntu-based images) may generate a temporary password for the ubuntu user at boot.
This password is displayed on the VM console during startup.

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How long does the rescue process take?

Typical timelines:

• Entering rescue mode: 1–2 minutes
• Troubleshooting duration: Depends on the issue
• Exiting rescue mode: 1–2 minutes

If the VM remains in a transitional state for longer than expected, check the console logs or contact support.

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Can I access files from my original VM while in rescue mode?

Yes.
Your original VM disk is attached to the rescue environment as a secondary disk (commonly /dev/vda, /dev/vdb, or /dev/vdc).

You can mount it manually to access and modify files from the original system.

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What happens to my data during rescue mode?

Your data remains safe and unchanged.

• Rescue mode does not modify your original disk automatically
• Only the boot method is temporarily changed
• Any changes occur only if you explicitly modify files on the mounted disk

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What should I do if rescue fails and the VM enters an error state?

If rescue or unrescue fails and the VM moves to an ERROR state:

1. Do not retry multiple times
2. Open a Helpdesk ticket immediately
3. Provide:
   • VM ID
   • Error message
   • Time of failure
   • Actions performed

Our support team may be able to recover the instance at the storage level.

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Is rescue mode secure?

Yes, with the following safeguards:

• Only authorized users with project access can initiate rescue
• Existing access controls and audit logs remain active
• No data is exposed unless explicitly accessed by the user

⚠️ Best Practice:
Exit rescue mode as soon as troubleshooting is complete to restore the VM to its normal security posture.

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Can I use a custom rescue image?

Yes, but only if it includes the required properties:

• hw_rescue_device=disk
• hw_rescue_bus=virtio

If these properties are missing, rescue may fail with a Driver Error.