> 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/how-to/how-to-enable-discard-trim-in-openstack-instance.md).

# How to Enable 'Discard/TRIM' in Openstack Instance ?

## Problem

* How do I enable `TRIM` (Discard) in a OpenStack KVM instance?

## Environment

* Platform9 Managed OpenStack - v5.4 and Higher

## Cause

* The default disk driver for KVM images is virtio. This driver does not supports / implements the fitrim IOCTL. Thus, it is needed to use virtio-scsi, which supports FITRIM.

## Resolution

* Create or modify a glance image adding the virtio-scsi disk bus property:

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

```javascript
# glance image-update --property hw_scsi_model=virtio-scsi --property hw_disk_bus=scsi <image>
```

{% endtab %}
{% endtabs %}

#### Or

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

```javascript
# openstack image set --property hw_scsi_model=virtio-scsi --property hw_disk_bus=scsi <image>
```

{% endtab %}
{% endtabs %}


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