# Different storage engines for part of nodes in replicaset

**URL:** <https://forums.percona.com/t/different-storage-engines-for-part-of-nodes-in-replicaset/39780>\
**Category:** Percona Operator for MongoDB\
**Created:** [November 25, 2025, 10:42am UTC](https://forums.percona.com/t/different-storage-engines-for-part-of-nodes-in-replicaset/39780 "2025-11-25T10:42:22Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Mr\_X](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/mr_x/32/22656_2.png) [@Mr\_X](https://forums.percona.com/u/Mr_X)\
**Post date:** [November 25, 2025, 10:42am UTC](https://forums.percona.com/t/different-storage-engines-for-part-of-nodes-in-replicaset/39780/1 "2025-11-25T10:42:22Z")

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## Description:

Good afternoon. I am trying to set up a cluster in inMemory mode. However, my current configuration does not survive a planned cluster shutdown. The official documentation recommends creating a hidden replica with priority 0 that uses the WiredTiger storage engine. In the current version (1.21.1) of CR, there is support for hidden replicas exist, but I was unable to configure different storage engine for them within the same replicaset. Could you please tell me if it is possible to configure this functionality using the operator?

## Steps to Reproduce:

setup cluster with inMemory storage with hidden replicas support

## Version:

1.21.1

## Expected Result:

setup cluster with inMemory storage engine with hidden replicas with wiredTiger storage engine

## Actual Result:

setup cluster with inMemory storage engine with hidden replicas with inMemory storage engine

## Additional Information:

[Include any additional information that could be helpful to diagnose the issue, such as browser or device information]

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<div class="post-metadata">

**Author:** ![Ivan\_Groenewold](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/ivan_groenewold/32/6299_2.png) [@Ivan\_Groenewold](https://forums.percona.com/u/Ivan_Groenewold)\
**Post date:** [November 25, 2025, 11:22am UTC](https://forums.percona.com/t/different-storage-engines-for-part-of-nodes-in-replicaset/39780/2 "2025-11-25T11:22:30Z")

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Hi, the operator currently does not have a way to specify the storage engine in the cr.yaml but you should be able to modify that via a configmap or secret adding the options:

```auto
storage:
  engine: inMemory

```

please see [Changing MongoDB options - Percona Operator for MongoDB](https://docs.percona.com/percona-operator-for-mongodb/options.html)

---

<div class="post-metadata">

**Author:** ![Mr\_X](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/mr_x/32/22656_2.png) [@Mr\_X](https://forums.percona.com/u/Mr_X)\
**Post date:** [November 25, 2025, 10:11pm UTC](https://forums.percona.com/t/different-storage-engines-for-part-of-nodes-in-replicaset/39780/3 "2025-11-25T22:11:09Z")

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As far as i know here it may be configured in cr.yaml, but only for whole replicaset with cli keys in pod entrypoint, which override settings from configmap or secret.

> <https://github.com/percona/percona-server-mongodb-operator/blob/main/deploy/cr.yaml#L154>

is there any way to change this behaviour for “hidden” mongodb pods within replicaset?