---
title: Virtual memory
description: By default, Elasticsearch uses memory mapping (mmap) to efficiently access indices. Usually, default values for virtual address space on Linux distributions...
url: https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/4236/deploy-manage/deploy/cloud-on-k8s/virtual-memory
products:
  - Elastic Cloud on Kubernetes
---

# Virtual memory
By default, Elasticsearch uses memory mapping (`mmap`) to efficiently access indices. Usually, default values for virtual address space on Linux distributions are too low for Elasticsearch to work properly, which may result in out-of-memory exceptions. This is why [the quickstart example](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/4236/deploy-manage/deploy/cloud-on-k8s/elasticsearch-deployment-quickstart) disables `mmap` through the `node.store.allow_mmap: false` setting. For production workloads, it is strongly recommended to increase the kernel setting `vm.max_map_count` to `262144` and leave `node.store.allow_mmap` unset.
The kernel setting `vm.max_map_count=262144` can be set on the host directly, by a dedicated init container which must be privileged, or a dedicated Daemonset.
For more information, check the Elasticsearch documentation on [Virtual memory](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/4236/deploy-manage/deploy/self-managed/vm-max-map-count).
Optionally, you can select a different type of file system implementation for the storage. For possible options, check the [store module documentation](https://docs-v3-preview.elastic.dev/elastic/elasticsearch/tree/main/reference/elasticsearch/index-settings/store).
```yaml
spec:
  nodeSets:
  - name: default
    count: 3
    config:
      index.store.type: niofs
```


## Using an Init Container to set virtual memory

To add an init container that changes the host kernel setting before your Elasticsearch container starts, you can use the following example Elasticsearch spec:
```yaml
cat <<EOF | kubectl apply -f -
apiVersion: elasticsearch.k8s.elastic.co/v1
kind: Elasticsearch
metadata:
  name: quickstart
spec:
  version: 9.2.2
  nodeSets:
  - name: default
    count: 3
    podTemplate:
      spec:
        initContainers:
        - name: sysctl
          securityContext:
            privileged: true
            runAsUser: 0
          command: ['sh', '-c', 'sysctl -w vm.max_map_count=262144']
EOF
```

Note that this requires the ability to run privileged containers, which is likely not the case on many secure clusters.

## Using a Daemonset to set virtual memory

To use a Daemonset that changes the host kernel setting on all nodes:
```yaml
cat <<EOF | kubectl apply -n elastic-system -f -
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: max-map-count-setter
  labels:
    k8s-app: max-map-count-setter
spec:
  selector:
    matchLabels:
      name: max-map-count-setter
  template:
    metadata:
      labels:
        name: max-map-count-setter
    spec:
      initContainers:
        - name: max-map-count-setter
          image: docker.io/bash:5.2.21
          resources:
            limits:
              cpu: 100m
              memory: 32Mi
          securityContext:
            privileged: true
            runAsUser: 0
          command: ['/usr/local/bin/bash', '-e', '-c', 'echo 262144 > /proc/sys/vm/max_map_count']
      containers:
        - name: sleep
          image: docker.io/bash:5.2.21
          command: ['sleep', 'infinity']
EOF
```

To run an Elasticsearch instance that waits for the kernel setting to be in place:
```yaml
cat <<'EOF' | kubectl apply -f -
apiVersion: elasticsearch.k8s.elastic.co/v1
kind: Elasticsearch
metadata:
  name: elasticsearch-sample
spec:
  version: 9.2.2
  nodeSets:
  - name: default
    count: 1
    # Only uncomment the below section if you are not using the previous Daemonset to set max_map_count.
    # config:
    #  node.store.allow_mmap: false
    podTemplate:
      spec:
        # This init container ensures that the `max_map_count` setting has been applied before starting Elasticsearch.
        # This is not required, but is encouraged when using the previous Daemonset to set max_map_count.
        # Do not use this if setting config.node.store.allow_mmap: false
        initContainers:
        - name: max-map-count-check
          command: ['sh', '-c', "while true; do mmc=$(cat /proc/sys/vm/max_map_count); if [ ${mmc} -eq 262144 ]; then exit 0; fi; sleep 1; done"]
EOF
```