System Requirements¶

CPU¶

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

The following CPUs are supported by Scylla:

• Intel core: Westmere or later (2010)

• Intel atom: Goldmont or later (2016)

• AMD low power: Jaguar or later (2013)

• AMD standard: Bulldozer or later (2011)

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 thread. Allow Scylla to run independently without any additional CPU intensive tasks on the same server/cores as Scylla.

SSD¶

We highly recommend SSD and local disks. Scylla is built for a large volume of data and large storage per node. You can use up to 100:1 Disk/RAM ratio, with 30:1 Disk/RAM ratio as a good rule of thumb; for example, 30 TB of storage requires 1 TB of RAM. We recommend a RAID-0 setup and a replication factor of 3 within the local datacenter (RF=3) when there are multiple drives.

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).

Disk Space¶

Scylla is flushing memtables to SSTable data files for persistent storage. SSTables are periodically compacted to improve performance by merging and rewriting data and discarding the old one. Depending on compaction strategy, disk space utilization temporarily increases during compaction. For this reason, you should leave an adequate amount of free disk space available on a node. Use the following table as a guidelines for the minimum disk space requirements based on the compaction strategy:

Use the default ICS (Scylla Enterprise) or STCS (Scylla Open Source) unless you’ll have a clear understanding that another strategy is better for your use case. More on choosing a Compaction Strategy. In order to maintain a high level of service availability, keep 50% to 20% free disk space at all times!

i3 instances¶

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

Source: Amazon EC2 I3 Instances

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.

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

See Amazon EC2 I3en Instances for details.

i4i instances¶

i4i support is available for ScyllaDB Open Source 5.0 and later and ScyllaDB Enterprise 2021.1.10 and later.

All i41 instances have the following specs:

• 3.5 GHz all-core turbo Intel® Xeon® Scalable (Ice Lake) processors

• 40 Gbps bandwidth to EBS in the largest size and up to 10 Gbps in the four smallest sizes (twice that of i3 instances. Up to 75 Gbps networking bandwidth (three times more than I3 instances).

• AWS Nitro SSD storage

See Amazon EC2 I4i Instances for specification details.

See ScyllaDB on the New AWS EC2 I4i Instances: Twice the Throughput & Lower Latency to learn more about using ScyllaDB with i4i instances.