Configure Scylla¶

System Configuration Files and Scripts¶

Several system configuration settings should be applied. For ease of use, the necessary scripts and configuration files are provided. Files are under dist/common and seastar/scripts in the Scylla source code and installed in the appropriate system locations. (For information on Scylla’s own configuration file, see Scylla Configuration.)

Bootloader Settings¶

If Scylla is installed on an Amazon AMI, the bootloader should provide the clocksource=tsc and tsc=reliable options. This enables an accurate, high-resolution Time Stamp Counter (TSC) for setting the system time.

This configuration is provided in the file /usr/lib/scylla/scylla_bootparam_setup.

Remove Crash Reporting Software¶

Remove the apport-noui or abrt packages if present, and set up a location and file name pattern for core dumps.

This configuration is provided in the file /usr/lib/scylla/scylla_bootparam_setup.

Set Up Network Time Synchronization¶

It is highly recommended to enforce time synchronization between Scylla servers.

Run ntpstat on all nodes to check that system time is synchronized. If you are running in a virtualized environment and your system time is set on the host, you may not need to run NTP on the guest. Check the documentation for your platform.

If you have your own time servers shared with an application using Scylla, use the same NTP configuration as for your application servers. The script /usr/lib/scylla/scylla_ntp_setup provides sensible defaults, using Amazon NTP servers if installed on the Amazon cloud, and other pool NTP servers otherwise.

Set Up RAID and Filesystem¶

Setting the file system to XFS is the most important and mandatory for production. Scylla will significantly slow down without it.

The script /usr/lib/scylla/scylla_raid_setup performs the necessary RAID configuration and XFS filesystem creation for Scylla.

Arguments to the script are

• -d specify disks for RAID

• -r MD device name for RAID

• -u update /etc/fstab for RAID

On the Scylla AMI, the RAID configuration is handled automatically in the /usr/lib/scylla/scylla_prepare script.

CPU Pining¶

When installing Scylla, it is highly recommended to use the scylla_setup script. Scylla should not share CPUs with any CPU consuming process. In addition, when running Scylla on AWS, we recommend pinning all NIC IRQs to CPU0 (due to the same reason). As a result, Scylla should be prevented from running on CPU0 and its hyper-threading siblings. To verify that Scylla is pinning CPU0, use the command below: If the node has four or fewer CPUs, don’t use this option.

To verify:

cat /etc/scylla.d/cpuset.conf

Example output:

--cpuset `1-15,17-31`

Networking¶

for irq in `cat /proc/interrupts | grep <networking iface name> | cut -d":" -f1`
do echo "Binding IRQ $irq to CPU0" echo 1 > /proc/irq/$irq/smp_affinity done

echo 4096 > /proc/sys/net/core/somaxconn
echo 4096 > /proc/sys/net/ipv4/tcp_max_syn_backlog

Configuring Scylla¶

Configuration for Scylla itself is in the Scylla Configuration section of the administration guide.

Development System Configuration¶

The following item is not required in production.

When working on DPDK support for Scylla, enable hugepages.

NR_HUGEPAGES=128
mount -t hugetlbfs -o pagesize=2097152 none /mnt/huge
mount -t hugetlbfs -o pagesize=2097152 none /dev/hugepages/
for n in /sys/devices/system/node/node?; do
    echo $NR_HUGEPAGES > $n/hugepages/hugepages-2048kB/nr_hugepages;
done

Huge page configuration is written to /etc/sysconfig/scylla-server by the script /usr/lib/scylla/sysconfig_setup

Related Topics¶

System Limits - outlines the system limits which should be set or removed.

Getting Started