virtual machine scale set, ephemeral linux drive permissions set to 755 cannot change to 777

Question

virtual machine scale set, ephemeral linux drive permissions set to 755 cannot change to 777

Dave Foster 0

Using Kubernetes. Ephemeral Linux drive attached to scale set has permissions set to 755. Our process needs to read and write temp information from/to the drive while server is up. We used to be able to change permissions to 777 but that is no longer working.

Manish Deshpande 1,170 Reputation points Microsoft External Staff Moderator

2025-12-03T00:51:42.4966667+00:00
Hello @Dave Foster

Thank you for contacting us about the VMSS issue.

Ephemeral Drive Limitations: Ephemeral drives in Azure typically have preset permissions, and depending on how your scale set is configured, there may be permissions settings enforced at a higher level that restrict your ability to set permissions to 777.

Azure VMSS Configuration: Check the Azure portal or your deployment scripts to ensure there are no policies or settings that revert permissions after changes are made. If your scale set is configured with specific images or contains custom scripts that run on startup, they might be enforcing these permissions.

Using Init Containers: If you haven’t done so, you might consider using an Init Container in your Kubernetes pod definition. An Init Container can run before your main application containers start and can be used to modify permissions on shared volumes or ephemeral drives.

Keep-alive Scripts: If the permissions keep reverting, you might want to add a keep-alive script that resets the permissions after deployment or on a schedule.

Are you using a custom image for your Virtual Machine Scale Set?

Have there been any recent changes to your Kubernetes setup or Azure configurations?

Could you provide more details about the specific error or issue you're encountering when trying to change the permissions?

Thanks,
Manish Deshpande
Jilakara Hemalatha 5,970 Reputation points Microsoft External Staff Moderator

2025-12-04T05:51:43.6733333+00:00

Hello @Dave Foster

Could you please check above response and let us know if you have any queries.

Additionally, could you please check private message and provide necessary details
Manish Deshpande 1,170 Reputation points Microsoft External Staff Moderator

2025-12-05T20:01:07.47+00:00

Hello @Dave Foster

Could you please check above response and let us know if you have any queries.

Additionally, could you please check private message and provide necessary details

1 answer

Your answer

Manish Deshpande 1,170 Reputation points Microsoft External Staff Moderator

2025-12-03T00:51:42.4966667+00:00

Hello @Dave Foster

Thank you for contacting us about the VMSS issue.

Ephemeral Drive Limitations: Ephemeral drives in Azure typically have preset permissions, and depending on how your scale set is configured, there may be permissions settings enforced at a higher level that restrict your ability to set permissions to 777.

Azure VMSS Configuration: Check the Azure portal or your deployment scripts to ensure there are no policies or settings that revert permissions after changes are made. If your scale set is configured with specific images or contains custom scripts that run on startup, they might be enforcing these permissions.

Using Init Containers: If you haven’t done so, you might consider using an Init Container in your Kubernetes pod definition. An Init Container can run before your main application containers start and can be used to modify permissions on shared volumes or ephemeral drives.

Keep-alive Scripts: If the permissions keep reverting, you might want to add a keep-alive script that resets the permissions after deployment or on a schedule.

Are you using a custom image for your Virtual Machine Scale Set?

Have there been any recent changes to your Kubernetes setup or Azure configurations?

Could you provide more details about the specific error or issue you're encountering when trying to change the permissions?

Thanks,
Manish Deshpande
Jilakara Hemalatha 5,970 Reputation points Microsoft External Staff Moderator

2025-12-04T05:51:43.6733333+00:00

Hello @Dave Foster

Could you please check above response and let us know if you have any queries.

Additionally, could you please check private message and provide necessary details
Manish Deshpande 1,170 Reputation points Microsoft External Staff Moderator

2025-12-05T20:01:07.47+00:00

Hello @Dave Foster

Could you please check above response and let us know if you have any queries.

Additionally, could you please check private message and provide necessary details

Answer 1

In Azure Virtual Machine Scale Sets, ephemeral disks are typically configured with specific permissions that can restrict how they are modified. If your ephemeral Linux drive is set to permissions of 755, this means that the owner has read, write, and execute permissions, while the group and others have read and execute permissions only.

The inability to change the permissions to 777 (which would allow read, write, and execute permissions for everyone) could be due to the underlying configuration of the ephemeral disk or the way Kubernetes is managing the volume.

To resolve this issue, consider the following steps:

Check the Volume Mount Options: Ensure that the volume is mounted with the correct options that allow for permission changes. Sometimes, the mount options might restrict permission changes.
Review Kubernetes Security Context: If you are using Kubernetes, check the security context of your pods. You might need to set the fsGroup or runAsUser to ensure that the permissions are set correctly when the pod starts.
Use Init Containers: If necessary, you can use an init container to set the permissions on the ephemeral drive before your main application container starts.
Consult Azure Documentation: For specific configurations related to Azure Virtual Machine Scale Sets and ephemeral disks, refer to Azure's documentation for any updates or changes in behavior regarding permissions.

If these steps do not resolve the issue, it may be beneficial to reach out to Azure support for further assistance regarding the permissions on ephemeral drives in your specific configuration.

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virtual machine scale set, ephemeral linux drive permissions set to 755 cannot change to 777

1 answer

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