# Troubleshooting Issues with Allocating Disk Space during Pre Run Checks on the NovaSeq X Series

**Background**

The NovaSeq X Series instrument uses data from the Flow Cell type and Sample Sheet to estimate the disk space required for a sequencing run and any configured analyses. Discrepancies between the run configuration specified by the flow cell and the Sample Sheet cause the disk space reservation process to fail and present the following Pre-Run Check error:

![](https://761066130-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FGM9W2DuBTgEXv1ClCm8H%2Fuploads%2Fgit-blob-ee5eb1f984bca5ec21411babebbba43797992e1c%2Fimage1.png?alt=media)

There was a problem allocating disk space for the run. Contact Illumina Technical support for help.

**Troubleshooting Actions**

See the following steps to troubleshoot this issue if this error message is observed:

1. Review the **Sample Sheet** used to setup the sequencing run and confirm the number of lanes specified in the **Lanes** column does not exceed the number of lanes on the Flow Cell.
   1. For example, ensure that the Sample Sheet does not specify more than Lanes 1&2 for a sequencing run using a 1.5B Flow Cell.
2. If the **Lanes** values exceed the number of available lanes, use **Run Planning** on instrument or on BaseSpace to generate a new sample sheet and correct the issue.
3. Repeat run setup using the corrected Sample Sheet.

If the Pre-Run Check issue persists after correcting the Sample Sheet, contact [Illumina Technical Support](https://www.illumina.com/company/contact-us.html) for further assistance.

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| *For any feedback or questions regarding this article (Illumina Knowledge Article #9383), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000009383%20-%20Instrumentation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |


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