Volumes in a Managed Kubernetes cluster

Managed Kubernetes uses local and network drives of the Cloud Platform.

You can use local and network drives in a Managed Kubernetes cluster as a boot drive and for data storage.

When choosing a drive, take into account the specifics of using local and network drives in Kubernetes.

Using network volumes and local disks in Kubernetes

	Local disks	Network volumes
Advantages	Low data access latency	Ability to store persistent data that needs to be preserved during pod restarts and migrations
Limitations	No data accessibility between pods	Additional network latency for data access
Objects in Kubernetes	Volume and VolumeMounts, PersistentVolumes and PersistentVolumeClaims (when installing the CSI driver manually)	PersistentVolumes and PersistentVolumeClaims
Usage	Boot volume Data storage	Boot volume Data storage

Boot volumes

Boot (system) volumes are used to start and initialize the operating system and applications in Kubernetes containers.

You can use local or network drives of the Cloud Platform as boot drives. For a network drive, you can choose the drive size; for a local drive, the size is fixed.

You select the boot disk when creating a cluster and cannot change it after the cluster is created. When choosing, consider that:

network volumes of the Universal SSD v2 and Fast SSD v2 types do not support changing the IOPS limit in a fault-tolerant multi-zonal cluster;
in some fixed configurations with GPUs, only a local disk is available.

When nodes are reinstalled, all data on the boot disks is deleted.

Nodes are reinstalled during:

when upgrading a minor version in a cluster on cloud servers;
reinstalling nodes manually;
auto-upgrading patch versions in a cluster on cloud servers;
node self-healing.

Data storage volumes

For data storage in Managed Kubernetes clusters, we recommend using PersistentVolumes (PV) on network drives.

If you have installed the CSI driver yourself and created a PV on a local disk, the data will be deleted when the node is removed.