Operating System Configuration

You must prepare the operating system with this configuration to run Ocient software:

To check the installation, run this command on each node to show the software version.

If the software is not installed or is the wrong version, see the Ocient Application Installation instructions.

In order to achieve high-performance levels, you must set specific kernel settings. You cannot set these settings at runtime. Therefore, the system must pass these parameters to the kernel at boot time.

You can automatically configure the kernel settings and apply them by running the ockernelparams script in the Ocient software package. This script detects the current system hardware and adjusts the grub bootloader kernel parameters. Then, the script updates the grub configuration with grub2-mkconfig or update-grub (depending on the Linux distribution).

Run this command and specify the appropriate node role.

Run this command to show the current settings for the kernel that is running.

The exact values can vary depending on the DRAM of the machine and the intended role for the node.

Check that the number of free 1G huge pages matches the number specified at the command line. You can check this number using this command.

Output

The returned value should match your configuration.

This section describes the optional kernel settings that you can manually configure. To automatically configure these settings, see Automatically Apply Kernel Settings.

You must add these settings that follow the grub bootloader kernel parameters for the listed applicable node types.

Setting: transparent_hugepages

Ocient requires that transparent_hugepages be disabled because Ocient software needs strict control over which huge pages it allocates.

Applicable Node Types:

Kernel setting:

Setting: isolcpus

To give Ocient software exclusive use of the majority of the cores on the system, the kernel is isolated from the cores using the isolcpus parameter. This isolation ensures that the system executes the kernel code only on a small number of cores where Ocient is not running logic that is critical for performance.

The pattern is to isolate all but the last two physical cores of each CPU from the kernel for CPUs with 26 or more cores. This means that two cores (4 threads) per CPU are available to the kernel.

For CPUs with fewer than 26 cores, all but the last physical core of each CPU is isolated.

Applicable Node Types:

Kernel setting:

Setting: Huge Pages

Ocient utilizes huge pages to streamline the management of large amounts of memory in the system. The system uses 2MB and 1GB huge pages, depending on the node type. These huge pages must be reserved at boot time because otherwise, the system memory quickly becomes too fragmented to allocate the number of huge pages needed at runtime. These settings are the expected huge page settings.



To prepare NVMe drives on Foundation Nodes, Loader Nodes, and SQL Nodes, these nodes must have the state where they are connected to the uio_pci_generic or vfio-pci driver and not contain a partition table. To initialize the drives for use by Ocient that have been previously partitioned, you must perform these steps.

1. Identify the OS drives. The OS drives have partitions that are mounted to mount points such as /. In this example, nvme0n1 is the OS drive.

2. Ensure all drives are bound to the NVMe driver so the NVMe drives show up as standard NVMe devices. List the NVMe drives to identify the drive identifiers.

3. For each NVMe drive that you need to erase and prepare for Ocient (not the OS drive), run this command by replacing X and Y to match the device name.

Some drives do not support the nvme format command. In that case, you can overwrite the partition table by zeroing out the beginning of the drive with this command. This command does not securely erase the whole drive, but does allow it to be used by Ocient.

4. Bind the drives to the UIO or VFIO driver by running this command. The script automatically chooses the appropriate driver after detecting if the IOMMU setting is enabled. Any NVMe drives with mounted partitions (i.e. the OS drive) remain on the NVMe driver. Show all expected NVMe drives on the node attached to the UIO or VFIO driver.

To bootstrap a node that was previously part of an Ocient System, you must clear a set of files from any previous setup of Ocient from the /var/opt/ocient/ directory. These commands remove these files.