c12s-kubespray/roles/kubernetes-apps/external_provisioner/local_volume_provisioner

Local Storage Provisioner

The local storage provisioner is NOT a dynamic storage provisioner as you would expect from a cloud provider. Instead, it simply creates PersistentVolumes for all manually created volumes located in the directory local_volume_provisioner_base_dir. The default path is /mnt/disks and the rest of this doc will use that path as an example.

Examples to create local storage volumes

tmpfs method:

for vol in vol1 vol2 vol3; do
mkdir /mnt/disks/$vol
mount -t tmpfs -o size=5G $vol /mnt/disks/$vol
done

The tmpfs method is not recommended for production because the mount is not persistent and data will be deleted on reboot.

Mount physical disks

mkdir /mnt/disks/ssd1
mount /dev/vdb1 /mnt/disks/ssd1

Physical disks are recommended for production environments because it offers complete isolation in terms of I/O and capacity.

File-backed sparsefile method

truncate /mnt/disks/disk5 --size 2G
mkfs.ext4 /mnt/disks/disk5
mkdir /mnt/disks/vol5
mount /mnt/disks/disk5 /mnt/disks/vol5

If you have a development environment and only one disk, this is the best way to limit the quota of persistent volumes.

Simple directories

for vol in vol6 vol7 vol8; do
mkdir /mnt/disks/$vol
done

This is also acceptable in a development environment, but there is no capacity management.

Usage notes

The volume provisioner cannot calculate volume sizes correctly, so you should delete the daemonset pod on the relevant host after creating volumes. The pod will be recreated and read the size correctly.

Make sure to make any mounts persist via /etc/fstab or with systemd mounts (for CoreOS/Container Linux). Pods with persistent volume claims will not be able to start if the mounts become unavailable.

Further reading

Refer to the upstream docs here: https://github.com/kubernetes-incubator/external-storage/tree/master/local-volume