> For the complete documentation index, see [llms.txt](https://platform9.com/kb/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://platform9.com/kb/pmo/frequently-asked-questions/vm-live-migration-fails-with-error--disk-of-instance-is-too-larg.md).

# VM live migration fails with error "Disk of instance is too large"

## Problem

* VM live migration fails with below error:

{% tabs %}
{% tab title="Bash" %}

```bash
2023-07-05 08:49:27.243 ERROR oslo_messaging.rpc.server [req-3469f20e-b1ef-43d5-85a9-1976bace495c user@example.com c435] Exception during message handling: nova.exception.MigrationPreCheckError: Migration pre-check error: Unable to migrate 3a8cc10a-e5a2-4507-952b-feff6ccd8262: Disk of instance is too large(available on destination host:-939524096000 < need:128849676288)
2023-07-05 08:49:27.243 TRACE oslo_messaging.rpc.server nova.exception.MigrationPreCheckError: Migration pre-check error: Unable to migrate 3a8cc10a-e5a2-4507-952b-feff6ccd8262: Disk of instance is too large(available on destination host:-939524096000 < need:128849676288)
```

{% endtab %}
{% endtabs %}

## Environment

* Platform9 Managed OpenStack - v5.4.0 and Higher

## Cause

* The host has disk capacity over-allocated because of which migration throws this error even when the disk has sufficient space available.

## Resolution

* Below command can be used to live migrate the VM:

{% tabs %}
{% tab title="Bash" %}

```bash
# openstack --os-compute-api-version 2.25 server migrate --block-migration --live <HOST_ID> --disk-overcommit <VM_ID>
```

{% endtab %}
{% endtabs %}


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