System Requirements

Supported Platforms

Scylla runs on 64-bit Linux. The following operating system releases are supported:

Linux distribution Version
CentOS/RHEL 7.2 and above
Ubuntu 14.04 *, 16.04
Ubuntu 18.04 **
Debian 8.6 and above (minor releases)
Debian 9.0 **

* Supported in Scylla 3.0 and below. Not supported in Scylla 3.1 and 2019.1 and above

** Supported in Scylla 2.3 and above

Note

Ubuntu 14 is not supported in future versions of Scylla Open Source 3.1 and Scylla Eneterprise 2019.1 and above. This is because Ubuntu has decided to EOL version 14. For more details refer to Ubuntu Release page.

For a more detailed list with recommendations refer to Operating System (OS) Support Guide.

Scylla requires a fix to the XFS append introduced in kernel 3.15 (back-ported to 3.10 in RHEL/CentOS). Scylla will not run with earlier kernel versions. Details in Scylla issue 885.

Hardware Requirements

It’s recommended to have a balanced setup. If there are only 4-8 Logical Cores, large disks or 10Gbps networking may not be needed. This works in the opposite direction as well. Scylla can be used in many types of installation environments. Each one has its own recommended hardware requirements. The three use cases most often used with their requirements include:

Installation Cores Memory Disk Network
Test, minimal 4 2 GB Single plain SSD 1 Gbps
Production 20 cores - 2 socket, 10 cores each 128 GB RAID-0, 4 SSDs, 1-5 TBs 10 Gbps
Analytics, heavy duty 28 cores - 2 socket, 14 cores each 256 GB - 1 TB NVMe, 10 TB 10-56 Gbps

Core Requirements

Scylla tries to maximize the resource usage of all system components. The shard-per-core approach allows linear scale-up with the number of cores. As you have more cores, it makes sense to balance the other resources, from memory to network.

CPU

Scylla requires modern Intel CPUs that support the SSE4.2 instruction set and will not boot without it.

In terms of the number of cores, any number will work since Scylla scales up with the number of cores. A practical approach is to use a large number of cores as long as the hardware price remains reasonable. Between 20-60 logical cores (including hyperthreading) is a recommended number. However any number will fit. When using virtual machines, containers, or the public cloud, remember that each virtual CPU is mapped to a single logical core, or hyperthread. Allow Scylla to run independently without any additional CPU intensive tasks on the same server/cores as Scylla.

Memory Requirements

The more memory available, the better Scylla performs, as Scylla uses all of available memory for caching. The wider the rows are in the schema, the more memory will be required. 64 GB-256 GB is the recommended range for a medium to high workload. Memory requirements are calculated based on the number of lcores you are using in your system.

  • Recommended size: 16 GB or 2GB per lcore (whichever is higher)
  • Maximum: 1 TiB per lcore, up to 256 lcores
  • Minimum:
    • For test environments: 1 GB or 256 MiB per lcore (whichever is higher)
    • For production environments: 4 GB or 0.5 GB per lcore (whichever is higher)

Disk Requirements

SSD

We highly recommend SSD and local disks. Scylla is built for a large volume of data and large storage per node. The rule of thumb is using 30:1 Disk/RAM ratio, for example, 30 TB of storage requires 1 TB of RAM. When there are multiple drives, we recommend a RAID-0 setup and a replication factor of 3 within the local datacenter (RF=3).

HDD

HDDs are supported but may become a bottleneck. Some workloads may work with HDDs, especially if they play nice and minimize random seeks. An example of an HDD-friendly workload is a write-mostly (98% writes) workload, with minimal random reads. If you use HDDs, try to allocate a separate disk for the commit log (not needed with SSDs).

Network Requirements

Network speed of 10 Gbps or more is recommended, especially for large nodes. To tune the interrupts and their queues, run the Scylla setup scripts.

Cloud Instance Recommendations

Cloud, AWS

We highly recommend EC2 I3 instances—High I/O. This family includes the High Storage Instances that provide very fast SSD-backed instance storage optimized for very high random I/O performance, and provide high IOPS at a low cost. We recommend on using enhanced networking that exposes the physical network cards to the VM.

i3 instances are designed for I/O intensive workloads and equipped with super-efficient NVMe SSD storage, it can deliver up to 3.3 Million IOPS. An i3 instance is great for low latency and high throughput, compared to the i2 instances, the i3 instance provides storage that it’s less expensive and denser along with the ability to deliver substantially more IOPS and more network bandwidth per CPU core.

i3 instances

Model vCPU Mem (GB) Storage (NVMe SSD)
i3.large 2 5.25 0.475 TB
i3.xlarge 4 30.5 0.950 TB
i3.2xlarge 8 61 1.9 TB
i3.4xlarge 16 122 3.8 TB
i3.8xlarge 32 244 7.6 TB
i3.16xlarge 64 488 15.2 TB
i3.metal New in version 2.3 72 * 512 8 x 1.9 NVMe SSD

* i3.metal provides 72 logical processors on 36 physical cores

Source: EC2 Instance Types

More on using Scylla with i3.metal vs i3.16xlarge

i3en instances

i3en instances have up to 4x the networking bandwidth of i3 instances, enabling up to 100 Gbps of sustained network bandwidth.

i3en support is available for Scylla Enterprise 2019.1.1 and higher and Scylla Open Source 3.1 and higher.

Model vCPU Mem (GB) Storage (NVMe SSD)
i3en.large 2 16 1 x 1,250 GB
i3en.xlarge 4 32 1 x 2,500 GB
i3en.2xlarge 8 64 2 x 2,500 GB
i3en.3xlarge 12 96 1 x 7,500 GB
i3en.6xlarge 24 192 2 x 7,500 GB
i3en.12xlarge 48 384 4 x 7,500 GB
i3en.24xlarge 96 768 8 x 7,500 GB

All i3en instances have the following specs:

  • 3.1 GHz all core turbo Intel® Xeon® Scalable (Skylake) processors
  • Intel AVX†, Intel AVX2†, Intel AVX-512†, Intel Turbo
  • EBS Optimized
  • Enhanced Networking

Refer to Amazon Web Services for specific information.

Cloud, GCE

Pick a zone where Haswell CPUs are found. Local SSD performance offers, according to Google, less than 1 ms of latency and up to 680,000 read IOPS and 360,000 write IOPS. The CentOS 7.x image with NVMe disk interface is recommended. (More info)

Model vCPU Mem (GB) Storage (GB)
n1-standard-8 8 30 eight 375 GB partitions for 3 TB
n1-standard-16 16 60 eight 375 GB partitions for 3 TB
n1-standard-32 32 120 eight 375 GB partitions for 3 TB
n1-himem-16 16 104 eight 375 GB partitions for 3 TB
n1-himem-32 32 208 eight 375 GB partitions for 3 TB

Getting Started