LINBIT VSAN User Guide

1. Introduction

LINBIT VSAN is a software-defined storage solution for hyper-converged infrastructure, based on LINBIT’s DRBD and LINSTOR.

It uses CentOS 8 as a foundation and utilizes software by LINBIT to provide highly available storage to hypervisors through a convenient iSCSI target.

It is built primarily with VMware ESXi as a target platform in mind, but it is fully independent of the hypervisor software, so it should also work on any other virtualization platform.

Warning

Please note that not all best practices recommended by LINBIT’s tech guides are implemented yet. For example, it is not yet possible to configure multiple links to separate application and replication traffic.

2. Architecture

Logically, LINBIT VSAN fits inbetween the hypervisor and the virtual machines it provides storage for.

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In practice, VSAN runs one of its instances as a virtual machine on each hypervisor in the cluster. The hypervisor passes its local storage through to VSAN, which then replicates its contents across the cluster. One of the VSAN virtual machines exports an iSCSI target through a static IP, which can then be fed back to the hypervisor in order to provide a highly available datastore. This in turn can be used to store virtual machines and disk images on solid, redundant storage.

3. Prerequisites

  • LINBIT customer credentials, which are also used to log in to LINBIT’s Customer Portal. You can get these by requesting an evaluation.

  • VSAN installation medium (ISO or OVA file). The download link will be sent to you when you request an evaluation.

  • A virtualization platform, such as VMware ESXi.

  • Internet access for all VSAN VMs.[1]

3.1. Node count

Because VSAN makes use of DRBD’s quorum mechanism, a VSAN cluster needs to consist of at least three member nodes.

The usual limitations and caveats of systems using quorum apply — for example, an odd number of nodes is greatly preferred over an even one. Please refer to the DRBD9 User’s Guide for more information.

4. Installation

LINBIT currently distributes VSAN in two formats, as an ISO image which gives a generic way to install VSAN on any kind of virtualization platform, and as an OVA file which can be imported into VMware ESXi easily and directly.

4.1. Installing via ISO file

Because VSAN is based on CentOS 8, you have to create one VM on each hypervisor node manually. You then need to attach a virtual or local disk for VSAN itself, and assign or pass-through local storage devices which will be used by VSAN for data replication. Make sure those local storage devices are untouched during VSAN installation (for example, do not create any partitions). Of course, one or more network adapters and IPs are mandatory for each VSAN VM.

Notice

Make sure you have your LINBIT customer credentials at hand and that all VSAN VMs can access the internet before you proceed. Also make sure that your subscription has enough allowed nodes for the VSAN deployment.

Start all VSAN VMs on all hypervisor nodes and install the Operating System step by step, similar to a regular CentOS 8 installation.

Warning

VSAN ISO contains a customized kickstart file to auto-configure CentOS 8, please do not install via your own kickstart file to automate the installation process!

4.1.1. Networking

VSAN relies on a network connection being made available on boot. By default, the CentOS installer configures the network interface to not automatically connect.

Please make sure that, when configuring the network interface, the “Connect automatically with priority” checkbox is checked.

vsan connect automatically

4.1.2. Time

In a cluster of multiple servers, it is important to ensure that the clocks of the individual nodes are in sync with each other.

This is easiest achieved by using NTP (Network Time Protocol). Please make sure that NTP is enabled in the CentOS setup and that the nodes’ clocks are synchronized after the installation is done.

4.2. Installing via OVA file

Simply import OVA file into your VMware Cluster, then deploy it to each ESXi node. Thanks to this pre-baked VMware image file, you do not have to install VSAN one by one, just assign or pass-through local storage devices to each of VSAN VMs and start all VSAN VMs, and you are done!

By default, the OVA image configures its network via DHCP. If you need to configure a different method (e.g. static IP or multiple IPs), you need to log into the VSAN VM with the default credentials, and configure it directly in CentOS 8.

Warning

When using the OVA image, the default password for the root user is set to linbit. It is highly recommended to log into the machine and change the password immediately after installation.

5. Initialization

After all VSAN VMs are installed and rebooted, access any one of them via your browser to setup VSAN. VSAN gives you a one-stop Web UI wizard to configure the storage cluster. Step by step screenshots can be found on LINBIT’s website, and there is also a walk-through video.

For general help with the terms and concepts used during the setup, please refer to the LINSTOR User’s Guide.

6. Administration

The VSAN Web UI is built to enable an administrator to handle most basic tasks with ease.

If you are familiar with the technologies under the hood, you are free to directly use the underlying operating system and treat it as a standard CentOS-based LINSTOR cluster.


1. Internet access is only required during the initial setup, not for continued operation.