> For the complete documentation index, see [llms.txt](https://documentation.2pintsoftware.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://documentation.2pintsoftware.com/deployr/reference/step-definitions/detect-disk-sector-size.md).

# Detect disk sector size

{% hint style="info" %}
This is only supported in DeployR Enterprise. Applies to: DeployR 1.4 and later.
{% endhint %}

The **Detect disk sector size** step reads the logical sector size of the specified disk and saves it in a task sequence variable named `DISKnSECTORSIZE`, where `n` is the disk number. For disk 0, the variable is `DISK0SECTORSIZE`. The value is `512` for standard disks and `4096` for 4K native disks.

| Option     | Description                                |
| ---------- | ------------------------------------------ |
| Disk index | Number of the disk to check. Default: `0`. |

The main use for this step is choosing the right FFU image: an FFU can only be applied to a disk with the same sector size as the disk it was captured from. Run this step in Windows PE before the [Apply FFU](/deployr/reference/step-definitions/apply-ffu.md) steps, then use the variable in each step's condition:

* `DISK0SectorSize` equals `512`: apply the image captured from a 512-byte sector disk.
* `DISK0SectorSize` equals `4096`: apply the image captured from a 4K native disk.

The value comes from the `Get-DeployRDiskSectorSize` cmdlet in the `DeployR.Utility` module, which you can also call from your own scripts.


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