Backends on Strata Documentation

ScyllaDB

Mon, 01 Jan 0001 00:00:00 +0000

ScyllaDB metadata backend#

ScyllaDB is supported as a drop-in replacement for Apache Cassandra. Strata’s metadata access path is gocql + CQL — no Cassandra-specific extensions are used — so the same internal/meta/cassandra backend talks to either cluster. The storetest.Run contract suite (35+ scenarios covering bucket/object/multipart LWT semantics, sharded objects listing, GC and notification queues, audit log, versioning null literal, access points, etc.) passes against both.

Compatibility status#

Code: zero gateway changes required to switch from Cassandra to ScyllaDB. Point STRATA_CASSANDRA_HOSTS (and friends) at a Scylla cluster and bring up the gateway as usual.
Schema: same DDL — internal/meta/cassandra/schema.go::tableDDL applies as-is. No ALTER differences.
Consistency: gateway uses LOCAL_QUORUM for reads/writes and LOCAL_SERIAL for LWT (internal/meta/cassandra/session.go). ScyllaDB honours both.
LWT: bucket creation, versioning toggle, multipart Complete, GC ack, storage-class transitions, lifecycle worker leases — all rely on IF NOT EXISTS / IF EXISTS. ScyllaDB 5.0 ships LWT on the Paxos protocol by default; ScyllaDB 5.4+ optionally enables Raft-backed LWT (raft_lwt-enabled tables) which dramatically reduces tail latency. The storetest contract is agnostic to the underlying coordination protocol; it only asserts the linearizable observable behaviour, which both Paxos and Raft modes provide.
Sharded objects listing: Strata fans out N=64 shard partitions in parallel (cassandra.Store.ListObjects). ScyllaDB’s per-shard CPU pinning is a natural fit for this access pattern — token-aware queries land on the right shard with a single hop.

Deployment notes#

Connection#

STRATA_CASSANDRA_HOSTS=scylla-1.example,scylla-2.example,scylla-3.example
STRATA_CASSANDRA_KEYSPACE=strata
STRATA_CASSANDRA_LOCAL_DC=datacenter1
STRATA_CASSANDRA_REPLICATION='{"class":"NetworkTopologyStrategy","datacenter1":"3"}'

STRATA_CASSANDRA_LOCAL_DC should match the Scylla dc you want token-aware routing to prefer. Multi-DC deployments work identically to Cassandra: NetworkTopologyStrategy keyspace + per-DC RF.

TiKV

Mon, 01 Jan 0001 00:00:00 +0000

TiKV metadata backend#

TiKV is a first-class metadata backend for Strata, on equal footing with Cassandra (and ScyllaDB as the CQL drop-in). The full meta.Store contract in internal/meta/storetest/contract.go runs against a real PD+TiKV cluster on every PR via .github/workflows/ci-tikv.yml.

The fundamental shape difference vs Cassandra is the objects table: TiKV keys are a flat ordered byte space, so ListObjects is a single ordered range scan instead of Cassandra’s 64-way fan-out + heap-merge. The gateway discovers this at runtime via the optional meta.RangeScanStore interface (internal/meta/store.go) and dispatches to the native scan path automatically — no operator action required.

S3-over-S3 data backend

Mon, 01 Jan 0001 00:00:00 +0000

S3 Data Backend#

The S3-over-S3 data backend stores object bytes in any S3-compatible bucket (AWS S3, MinIO, Ceph RGW, Garage). One Strata object = one backend S3 object under the key <bucket-uuid>/<object-uuid>. RADOS remains the default and recommended data backend; this page covers the S3 alternative.

When to choose S3 over RADOS#

Question	Pick RADOS if	Pick S3 if
Existing infra investment	Operator already runs Ceph	Operator already runs MinIO / has AWS account / wants Garage
Tail latency budget	< 5 ms p99 GET on hot data is critical	50–200 ms p99 GET is acceptable (HTTPS round-trip floor)
Bytes-stored cost model	Self-hosted hardware, want bare-metal economics	Cloud storage tiers (Standard-IA, Glacier) carry the lifecycle
Availability boundary	Single-DC, hardware-controlled	Multi-AZ via the cloud provider’s bucket SLA
Encryption-at-rest mandate	Strata-side envelope encryption is enough	Want backend SSE / KMS independent of Strata
Operational complexity	Team owns Ceph operations	Team owns S3 operations (or has zero ops via AWS)

The two backends are equal-tier alternatives — pick by what your operations team already runs. Mixing within a single Strata deployment is not supported (STRATA_DATA_BACKEND is a single-value flag).