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The following options are available to specify storage policies to apply to the objects it contains when editing the Properties of a domain or bucket:

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A domain or bucket inherits the protection settings in force above it (cluster, domain) by default.

Info

Required

Grant users these specific permissions: PutDomain and CopyBucket if users are allowed to change the content policies (replication, erasure coding, or versioning) on a domain or bucket through the Content UI.

  • To see the options for a storage policy, deselect the Inherit checkbox, which expands the policy section.

  • For guidance about the policy options, click the information icon, which toggles the help text.

Protection

Swarm allows flexibility in determining the type and level of content protection best fitting the storage needs. In Swarm storage, objects can be replicated and/or erasure-coded, with objects of both types co-existing in the same cluster.

Info

Tip

Erasure coding helps cost-effectively scale clusters with many nodes and larger objects, while replication is better for smaller clusters and with smaller objects.

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  • Default Replicas: Accept the inherited number or enter how many replicas are desired (subject to existing min and max values and query arguments).

  • Minimum and maximum Maximum Replicas: A minimum number of replicas is two and the maximum is sixteen for an object.

  • Anchored: Select to override any lower-level policies.

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  • Enabled: Select to allow erasure coding at this level and below (subject to higher-level policies). 

  • EC Size Threshold (MB): (not settable) Reports the object size that triggers erasure coding rather than replication. 

  • Default Encoding: Accept the inherited encoding, or enter data (k) and parity (p) values such as these examples:

    • 5 : 2 (1.4x footprint) - protection for 2 simultaneous disk failures.

    • 9 : 6 (1.7x footprint) - protection for 6 simultaneous disk failures and 1 subcluster failure in clusters of 3 or more subclusters.

  • Anchored: Select to override any lower-level policies.

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For implementation, see Implementing EC Encoding Policy.

Versioning

Swarm supports object-level versioning, which is a powerful content protection option that tracks, secures, and provides access to historical versions of objects, even after they are deleted. With versioning, applications can read, list, revert, and purge prior versions as well as restore objects deleted by mistake.

Tip

Best Practice

  • Plan for higher disk utilization with versioning: each update to a versioned object adds a new object to the cluster (one object updated twice results in three objects stored).

  • Where possible, make use of lifepoints to control the lifetime – and thus the cost of storing – multiple versions of objects.

  • For optimal resource management, limit versioning to the specific domains and/or buckets for which it is needed.

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Info

Important

By default, versioning is disabled at the cluster and every other level. Versioning must be enabled for the cluster through the Swarm configuration setting policy.versioning. Cluster-level values are disallowed (default), suspended, and allowed. In a cluster with versioning allowed, every newly created domain and bucket starts with an unspecified state, so object versioning is disabled until enabled there explicitly.

Info

Reminder

The versioning option selected depends on what is permitted in the given context. Versioning occurs in a cluster that allows it but not in one that disallows it, such as a remote replication cluster if a domain has versioning enabled.

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