hsmalley / hpc-zram-systemd

HPC zram Script for systemd on RHEL7/CentOS7

HPC-zram-systemd

HPC zram Script for systemd on RHEL 7 / CentOS 7

Getting Started

This script and unit file will get zram swap working on RHEL7/CentOS7 on default minimal install.

Prerequisites

Red Hat Enterprise Linux 7, CentOS 7 or similar

If you're using Red Hat Enterprise Linux 8, Rocky 8, or similar use the zram-generator.

Kernel options vm.overcommit_memory, vm.page-cluster, vm.spwapiness have their defaults below:

vm.overcommit_memory=0
vm.page-cluster=3
vm.spwapiness=60

Variable FACTOR in zram script set the % of system RAM used for zram swap.

10% is a sane default to start with, tune to for your workloads.

This generates as many zram devices as CPUs. This because the default kernel doesn't support compression streams (/sys/block/zram0/max_comp_streams).

Installing

Use install.sh to install.

Tuning Options

I configured the tuning options to variables in the script. Modify them to suite your needs. I have them configured best for HPC workloads

See also

Systemd ZRAM-Generator

Chapter 7. Memory

7.5. Configuring System Memory Capacity

Linux kernel tuning for GlusterFS