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Durability, quotas and billing

Durability

Ceph spreads your data across many disks and several hosts, and protects it with one of two redundancy schemes depending on the storage type and pool:

  • 3-way replication keeps three full copies of every object on different hosts. It is fast and rebuilds quickly, at the cost of using three times the raw capacity.
  • Erasure coding splits data into shards plus parity, so it survives failures with much less storage overhead than three full copies. It is used where capacity efficiency matters more than the lowest possible latency.

Either way, if a disk or a whole node fails, the data is still served from the remaining copies or shards and Ceph rebuilds the missing redundancy automatically. You do not need to configure RAID or replication yourself.

This protects against hardware failure. It does not protect against:

  • Deleting data yourself (the delete is replicated immediately).
  • An application or ransomware overwriting or encrypting your files.
  • Deleting a volume together with all of its snapshots.

For those cases you need a backup that lives outside the cluster, or at least object versioning with a lifecycle policy you control.

What is not backed up by default

Object (S3), block, and filesystem storage are not backed up by Sunet unless you have specifically ordered a backup service. Plan your own strategy:

  • For S3, enable versioning and lifecycle rules, or copy critical buckets to another location with rclone or aws s3 sync.
  • For OpenStack volumes, take and export snapshots, or back up at the application level (for example database dumps to S3).
  • For Kubernetes, back up persistent volumes and cluster state, for example with Velero.

Quotas

Storage capacity is allocated per project. If you reach a quota, requests to write more data or create new volumes will fail until you free space or ask Sunet to raise the quota. Contact Sunet support to adjust a project's storage quota.

Billing

Storage is billed on usage per month. Object storage (S3) is billed per gigabyte stored, with lower rates for longer commitment terms; block storage is billed per gigabyte by tier. Usage is metered and aggregated across all of an organisation's projects.

For current, authoritative pricing, see the official Sunet VDC price list.