## Introduction

Local storage offers faster access speeds than alternatives because data is stored directly on the node. And you can combine that with the benefits of bare-metal machines to make your storage surprisingly cost-effective.

{% callout type="note" %}

Currently, persistent local storage is only available for bare metal servers. This setup is not available in hcloud nodes.

{% /callout %}

Normally, this would mean a complex setup with higher maintenance costs. But with Syself Autopilot, we take that burden off your shoulders by simplifying every step. We enable you to persist data through cluster updates or even when you need to re-provision the machines, making it ideal for storage-intensive workloads such as databases.

This guide will walk you through the process of configuring your cluster and machines to use local storage with TopoLVM, a one-time process that allows you to efficiently use storage attached directly to your servers and rely on Autopilot for lifecycle automation.

{% callout type="warning" %}

Most of the procedure described in this guide will be automated in the upcoming release of Syself Autopilot. Please stick to the configuration options described here to guarantee compatibility.

{% /callout %}

## 1. Deploy cert-manager

You need to have `cert-manager` version `v1.7.0` or higher installed on your cluster as a dependency of TopoLVM. Install it with the following command:

{% terminal height="8rem" steps="[{\"command\":\"helm repo add jetstack https://charts.jetstack.io\"},{\"command\":\"helm repo update\"},{\"command\":\"helm template --namespace=kube-system cert-manager jetstack/cert-manager --set installCRDs=true | kubectl apply -n kube-system -f -\"}]" /%}

You can follow the [official guide](https://helm.sh/docs/intro/install/) on installing `helm` if you don't have it.

{% callout type="warning" %}

To guarantee compatibility with future Autopilot releases, **don't** use `helm install`, as our automation will create the resources directly instead of installing charts.

{% /callout %}

## 2. Deploy TopoLVM

We use the TopoLVM CSI driver for local storage on bare-metal. You can follow the steps below to deploy it to your workload cluster.

1. Add the Syself helm repository:

   {% terminal height="6.5rem" steps="[\"helm repo add syself https://charts.syself.com\",\"helm repo update\"]" /%}

2. Template the TopoLVM chart and apply it to the cluster:

   {% callout type="warning" %}

   Do **not** use `helm install`. This chart will be added as a base feature in later versions of Syself Autopilot, so stick to the installation steps shown here to guarantee compatibility. Use the command below to install it with `helm template` and `kubectl apply` to the `kube-system` namespace.

   {% /callout %}

   {% terminal height="5rem" steps="[\"helm template --namespace=kube-system csi-local syself/topolvm | kubectl apply -n kube-system -f -\"]" /%}

   Now the storage space in your bare-metal server is exposed to your cluster via the `local-nvme` Storage Class:

   {% terminal height="14rem" steps="[{\"command\":\"kubectl get storageclasses\",\"output\":\"NAME                  PROVISIONER         RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION\\nlocal-hdd             topolvm.io          Retain          WaitForFirstConsumer   true\\nlocal-nvme            topolvm.io          Retain          WaitForFirstConsumer   true\\nlocal-ssd             topolvm.io          Retain          WaitForFirstConsumer   true\\nstandard (default)    csi.hetzner.cloud   Retain          WaitForFirstConsumer   true\"}]" /%}

## 3. Configure your servers

In this step, you'll define the _physical volumes_ and _volume groups_ in your disks to be used by TopoLVM.

{% callout %}

We support all three types of disks: HDD, SATA SSD, and NVMe SSD. If your server, for example, only has NVMe, you should only follow the steps for NVMe and cannot use the storage classes `local-ssd` or `local-hdd`.

If your server has NVMe, SSD, and HDD, you can use all three storage classes.

{% /callout %}

1. Access your server via ssh:

   {% terminal height="5rem" steps="[\"ssh -i path-to-your/ssh-key -p 100 root@<machine-ip>\"]" /%}

1. List your disks with `lsblk`:

   {% terminal height="14rem" steps="[{\"command\":\"lsblk\",\"output\":\"NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS\\nnvme1n1     259:0    0 476.9G  0 disk \\nnvme0n1     259:1    0 476.9G  0 disk \\n|-nvme0n1p1 259:2    0   512M  0 part /boot/efi\\n|-nvme0n1p2 259:3    0     1G  0 part /boot\\n`-nvme0n1p3 259:4    0 475.4G  0 part /\"}]" /%}

1. Identify if the disk(s) you want to use is an HDD, SATA SSD, or NVMe SSD.

   {% callout type="warning" %}

   Don't use your OS disk (`nvme0n1` in the above output), as this can lead to data loss.

   {% /callout %}

   {% callout type="tip" %}

   To identify the type of disk you have, you can look at the first column `NAME` and third column `RM` of the `lsblk` output.
   - An NVMe disk will have `nvme` at the beginning of its name, otherwise:
   - A SATA SSD disk will have the value 0 in the `RM` column.
   - A HDD disk will have the value 1 in the `RM` column.

   {% /callout %}

1. Create a physical volume (point to every disk in your server where you want to store data) with `pvcreate /dev/[disk-name]`. For example:

   {% terminal height="5rem" steps="[\"pvcreate /dev/nvme1n1\"]" /%}

1. Map the disks to the appropriate volume group type with `vgcreate vg-[type] /dev/[disk-name] /dev/[other-disk]`. For example:

   {% terminal height="5rem" steps="[\"vgcreate vg-nvme /dev/nvme1n1\"]" /%}

   If you missed a disk and want to add it later, extend the volume group with `vgextend vg-[type] /dev/[new-disk]`. For example:

   {% terminal height="5rem" steps="[\"vgextend vg-nvme /dev/nvme2n1\"]" /%}

   {% callout type="note" title="Available volume group types" %}
   - For NVMe disks you use: `vg-nvme`
   - For SATA SSD disks you use: `vg-ssd`
   - For HDD disks you use: `vg-hdd`

   {% /callout %}

1. Repeat the previous steps for every disk you want to use.
1. After adding all disks to their respective volume groups, create a thin provisioned logical volume for each volume group. This step is done once per volume group, not per disk: Create a thin provisioned logical volume with `lvcreate --thinpool pool-[type] --extents 100%FREE vg-[type]`.

   {% tabs #storage-types %}
   {% tab title="NVMe" %}
   {% terminal height="5rem" steps="[\"lvcreate --thinpool pool-nvme --extents 100%FREE vg-nvme\"]" /%}
   {% /tab %}
   {% tab title="SSD" %}
   {% terminal height="5rem" steps="[\"lvcreate --thinpool pool-ssd --extents 100%FREE vg-ssd\"]" /%}
   {% /tab %}
   {% tab title="HDD" %}
   {% terminal height="5rem" steps="[\"lvcreate --thinpool pool-hdd --extents 100%FREE vg-hdd\"]" /%}
   {% /tab %}
   {% /tabs %}

## 4. Use it!

You can use the newly created Storage Classes in the same way you would use any other.

Local storage can be up to 100 times faster than storage provided over the network. However, it provides no redundancy out of the box.

Some services handle replication and backups on their own, such as database operators. In these cases, local storage is a great option. For other services, it is advised to setup replication and disaster recovery.

{% callout title="Available storage classes" %}

By default, you have Storage Classes for all three disk types available in your cluster:

- For NVMe disks: `local-nvme`
- For SATA SSD disks: `local-ssd`
- For HDD disks: `local-hdd`

If you use a Storage Class for a disk type unavailable in your machine volume groups, your workload will be stuck at provisioning. We include all three to make your cluster ready for any new disks you might add in the future.

{% /callout %}

If you want to test your new setup:

1. Create a `pv-claim.yaml` file with the following content:

   ```yaml
   /// pv-claim.yaml
   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: pv-claim
   spec:
     storageClassName: local-nvme
     accessModes:
       - ReadWriteOnce
     resources:
       requests:
         storage: 1Gi
   ```

1. And apply it with `kubectl apply -f pv-claim.yaml`.
1. Create a `pod.yaml` file with the following content:

   ```yaml
   apiVersion: v1
   kind: Pod
   metadata:
     name: pv-pod
   spec:
     volumes:
       - name: pv-storage
         persistentVolumeClaim:
           claimName: pv-claim
     containers:
       - name: pv-container
         image: nginx
         ports:
           - containerPort: 80
             name: http-server
         volumeMounts:
           - mountPath: /usr/share/nginx/html
             name: pv-storage
   ```

1. And apply it with `kubectl apply -f pod.yaml`.

   Now, all the data stored in the container under `/usr/share/nginx/html` will be in `/mnt/data` on your machine.

   {% callout %}

   In this example, we used the `local-nvme` class, but you can also use `local-hdd` and `local-ssd` too if your servers have disks of those types attached.

   {% /callout %}

1. Create a test file in your pod:

   {% terminal height="6.5rem" steps="[\"kubectl exec -it pv-pod -- /bin/sh\",\"echo 'Hi from Kubernetes to bare metal!' > /usr/share/nginx/html/hi.txt\"]" /%}

1. Now delete the pod, so we are sure the storage is persistent, and not ephemeral: `kubectl delete pod pv-pod`

1. Apply the pod again with `kubectl apply -f pod.yaml`. Show the content of the `hi.txt` file:

   {% terminal height="6.5rem" steps="[{\"command\":\"cat /mnt/data/hi.txt\",\"output\": \"Hi from Kubernetes to bare metal!\"}]" /%}