# Ephemeral Storage with emptyDir – Data Still Written to Disk not ephemeral storage

**URL:** <https://discuss.kubernetes.io/t/ephemeral-storage-with-emptydir-data-still-written-to-disk-not-ephemeral-storage/31671>\
**Category:** General Discussions\
**Created:** [February 24, 2025, 8:14am UTC](https://discuss.kubernetes.io/t/ephemeral-storage-with-emptydir-data-still-written-to-disk-not-ephemeral-storage/31671 "2025-02-24T08:14:15Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![isaac](https://sea2.discourse-cdn.com/flex016/user_avatar/discuss.kubernetes.io/isaac/32/16967_2.png) [@isaac](https://discuss.kubernetes.io/u/isaac)\
**Post date:** [February 24, 2025, 8:14am UTC](https://discuss.kubernetes.io/t/ephemeral-storage-with-emptydir-data-still-written-to-disk-not-ephemeral-storage/31671/1 "2025-02-24T08:14:15Z")

</div>

### Cluster information:

Kubernetes version: 1.29.9  
Cloud being used: Azure  
Installation method: AKS managed  
Host OS: Ubuntu 22.04

I’ve observed that even when specifying ephemeral storage resource requests/limits and using an emptyDir volume in our Pod, data ends up being written to disk rather than staying in ephemeral space.

> **[Volumes](https://kubernetes.io/docs/concepts/storage/volumes/#emptydir)**
>
> Kubernetes volumes provide a way for containers in a pod to access and share data via the filesystem. There are different kinds of volume that you can use for different purposes, such as:
> populating a configuration file based on a ConfigMap or a...

Observed Behavior:  
In our case, the Pod’s configuration uses an emptyDir (without specifying the medium). When checking the mount point (e.g., via `mount | grep /rocksdb-state`), it shows the volume is backed by `/dev/root` (an ext4 disk). For example, the output is :- /dev/root on /rocksdb-state type ext4

Steps to Reproduce:

1. Create a Pod with a configuration example:  
containers:

- name: test-container  
image: ubuntu  
volumeMounts:
  - name: rocksdb-storage  
mountPath: /rocksdb-state  
resources:  
requests:  
ephemeral-storage: “30Gi”  
limits:  
ephemeral-storage: “40Gi”  
volumes:

- name: rocksdb-storage  
emptyDir: {}

1. Deploy the Pod and exec into it.
2. after verifying that data is being written to `/rocksdb-state` and inspect the mount using:  
mount | grep “/rocksdb-state”

expected Behavior:  
From the documentation, emptyDir volumes by default use the node’s disk unless explicitly configured to use memory.  
expected after setting ephemeral-storage resource requests/limits might cause the data to be managed as truly ephemeral storage. However, without specifying `medium: "Memory"`, the emptyDir remains disk-backed.

Actual Behavior:  
the emptyDir volume is disk-backed even though it’s intended for ephemeral storage. This creates some confusion regarding the interaction between ephemeral-storage requests/limits and the emptyDir volume.

I’m open to suggestions, corrections or alternative approaches that might help touse ephemeral storage instead of disk for my usecase.  
Thanks in advance