Configuring Lightbits Target Virtual Machines

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This article details how to prepare the Lightbits storage VMs for running the Ansible installer packages and creating a cluster.

SSH into your Lightbits target VM using a method described in the SSH Into An Azure VM section.

Installing wget

To pull packages, we will use wget. If you have another preferred tool, you can use your organization's best practices instead.

sudo yum install -y wget

Installing the Correct Kernel

Lightbits software involves installing Lightbits proprietary kernel modules on the VMs in the storage cluster. As a result, a specific kernel must be used. The mapping of kernels to Lightbits versions is outlined below.

As noted in the table, releases 3.4.1 and above live in user space. This step can therefore be skipped since the kernel is no longer relevant. Please move on to the Disabling SELinux section.

Lightbits Release	Release Type	Kernel Version	Supported OS
3.7.1~b1548	RHEL	User space	Alma, RHEL, Rocky (8 & 9)
3.6.1~b1503	RHEL	User space	Alma, RHEL, Rocky (8 & 9)
3.5.1~b1443	RHEL	User space	Alma, RHEL, Rocky (8 & 9)
3.4.1~b1397	RHEL	User space	Alma, RHEL, Rocky (8 & 9)
3.3.1~b1335	RHEL	4.18.0_477.13.1.el8	Alma, Red Hat 8.7
3.2.1~b1252	RHEL	4.18.0-425.19.2.el8	Alma, Red Hat 8.6
3.1.2~b1127	RHEL	4.18.0_425.3.1.el8	Alma, Red Hat 8.6
3.1.1~b1119	RHEL	4.18.0-425.3.1.el8	Alma, Red Hat 8.6

In this guide, the examples illustrate using Lightbits release 3.2.1.

Azure does not allow for fully configuring RHEL kernel versions, so we will illustrate how to use Alma open source kernels. If your organization has access to the RHEL kernels, follow your organization's internal best practices.

Download the kernel packages from the Alma repository, using wget.

wget https://repo.almalinux.org/almalinux/8.7/BaseOS/x86_64/os/Packages/kernel-core-4.18.0-425.19.2.el8_7.x86_64.rpm wget https://repo.almalinux.org/almalinux/8.7/BaseOS/x86_64/os/Packages/kernel-modules-4.18.0-425.19.2.el8_7.x86_64.rpm wget https://repo.almalinux.org/almalinux/8.7/BaseOS/x86_64/os/Packages/kernel-4.18.0-425.19.2.el8_7.x86_64.rpm

Install the kernel packages.

sudo rpm -i "kernel-core-4.18.0-425.19.2.el8_7.x86_64.rpm" sudo rpm -i "kernel-modules-4.18.0-425.19.2.el8_7.x86_64.rpm" sudo rpm -i "kernel-4.18.0-425.19.2.el8_7.x86_64.rpm"

Set the kernel in grubby.

sudo grubby --set-default="/boot/vmlinuz-4.18.0-425.19.2.el8_7.x86_64"

Prevent the yum update from changing the kernel version.

echo 'exclude=redhat-release* kernel* kmod-kvdo*' | sudo tee -a /etc/yum.conf

Installing IP Tables

For Lightbits, we use iptables by default.

Install iptables.

sudo yum install -y iptables

Disabling SELinux

For the Lightbits installation to succeed, SELinux must be disabled.

Disable SELinux.

sudo sed -i 's/^SELINUX=.*$/SELINUX=disabled/' /etc/selinux/config

Enabling Persistent Journaling

To aid with troubleshooting and support, Lightbits recommends setting the journal to keep logs even after reboots and shutdowns. To ensure that the OS disk does not fill up, Lightbits also recommends updating the log rotation.

Enable persistent journaling.

sudo sed -i 's/#Storage.*/Storage=persistent/' /etc/systemd/journald.conf

Enable log rotation.

sudo sed -i 's| missingok$| daily\n rotate 30\n compress\n missingok\n notifempty|g' /etc/logrotate.d/syslog

Rebooting as Needed

To ensure that the kernel changes have been applied, reboot the virtual machine.

sudo shutdown -r now

Repeating the Process as Needed

Repeat the above process for all virtual machines that will be a part of the Lightbits storage cluster.

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