To add a virtual disk with a source path using virsh on Debian 13 (or any system using libvirt), you typically need to:

1. Edit the VM's XML configuration to define the new disk.
2. Attach the disk to the VM using the updated XML.

Here’s how you can do it:

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Step 1: Shut Down the VM (if running)

If the VM is running, shut it down first:

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virsh shutdown <vm-name>
virsh destroy <vm-name>  # Force stop if needed

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Step 2: Edit the VM's XML Configuration

Use virsh edit to modify the VM's configuration:

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virsh edit <vm-name>

In the XML editor, locate the <devices> section and add a new <disk> entry. For example, to add a raw disk image (e.g., /path/to/disk.img), use:

xml
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<disk type='file' device='disk'>
  <driver name='qemu' type='raw'/>
  <source file='/path/to/disk.img'/>
  <target dev='vdb' bus='virtio'/>
</disk>

Key Attributes:

• type='file': Specifies the disk is a file (use type='block' for physical devices like /dev/sdX).
• device='disk': Treats the disk as a storage device (other options: cdrom, floppy).
• <source file='...'>: Path to the disk image or block device.
• <target dev='vdb' bus='virtio'>:
  • dev='vdb': The device name (e.g., vda, vdb, sda, etc.).
  • bus='virtio': The bus type (recommended for performance; alternatives: ide, scsi, sata).

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Step 3: Save and Exit

Save the changes in the editor. The VM's configuration will update automatically.

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Step 4: Start the VM

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virsh start <vm-name>

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Alternative: Attach a Disk Temporarily (Hotplug)

If the VM is running and supports hotplugging, you can attach a disk without editing the XML:

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virsh attach-disk <vm-name> /path/to/disk.img vdb --type disk --mode shareable --persistent

• --persistent: Ensures the disk remains attached after a reboot.
• --mode shareable: Allows the disk to be shared (optional).

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Verify the Disk

Check if the disk is attached:

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virsh domblklist <vm-name>

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Notes:

• Replace <vm-name> with your VM's name.
• For QCOW2 or other formats, change type='raw' to type='qcow2'.
• For physical disks (e.g., /dev/sdX), use:

  xml
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  <disk type='block' device='disk'>
    <driver name='qemu' type='raw'/>
    <source dev='/dev/sdX'/>
    <target dev='vdb' bus='virtio'/>
  </disk>