Performance & Tiering
A dedicated cluster lets you match device classes and data-protection schemes to each workload, rather than accept a one-size-fits-all tier.
NVMe as a fast tier or cache
Section titled “NVMe as a fast tier or cache”You use NVMe drives two ways:
- As a dedicated fast pool. Place latency-sensitive workloads (databases, metadata, hot buckets) on an all-NVMe pool, and bulk or cold data on high-capacity drives.
- As a cache layer for spinning disks. Front high-capacity HDDs with NVMe so frequently accessed data is served from flash.
A modest amount of NVMe paired with high-capacity drives delivers strong performance per GB stored, without paying for all-flash capacity.
Replication vs erasure coding
Section titled “Replication vs erasure coding”Per pool, pick the data-protection scheme for the workload:
- Replication (for example 3x). Lowest latency and simplest recovery. Higher raw-capacity overhead.
- Erasure coding. Much better usable-to-raw capacity ratio. Best for large, throughput-oriented or archival data.
Mixing schemes across pools in the same cluster lets you tune cost and performance per workload.
| Resource | URL |
|---|---|
| Ceph pools | https://docs.ceph.com/en/latest/rados/operations/pools/ |
| CRUSH / device classes | https://docs.ceph.com/en/latest/rados/operations/crush-map/ |
| Erasure coding | https://docs.ceph.com/en/latest/rados/operations/erasure-code/ |