HCP services are responsible for optimizing the use of system resources and maintaining the integrity and availability of the stored data. Each of the services performs a specific function that contributes to the overall health and viability of the system.
The following HCP services are available for selection when utilizing the Objects Processed and Objects Processed Per Second visualizations for a dashboard in the Monitor App:
- Capacity Balancing
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The Capacity Balancing service ensures that the percent of HCP storage space used on the storage nodes in the system remains roughly equivalent across the nodes when new nodes are added.
- Compression
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The Compression service compresses object data so as to make more efficient use of HCP storage space. The space reclaimed by compression can be used to store additional objects.
- Content Verification:
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The Content Verification service ensures the integrity of each object by:
- Verifying that the object data, system metadata, and custom metadata still match the stored cryptographic hash values.
- Ensuring that certain secondary metadata other than the hash value matches the primary metadata for the object.
- Disposition
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The Disposition service automatically deletes expired objects. An object is expired if either of these is true:
- The object has a retention setting that’s a specific date and time, and that date and time is in the past.
- The object has a retention setting that’s a retention class, and the date and time calculated from the duration specified by the retention class is in the past. In this case, the Disposition service deletes the object only if the retention class has disposition enabled.
- Duplicate Elimination
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Duplicate elimination is the process of merging the data associated with two or more identical objects. For objects to be identical, their data content must match exactly. By eliminating duplicates, HCP increases the amount of space available for storing additional objects.
- Erasure Coding
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The Erasure Coding service is responsible for ensuring that objects that are or have ever been subject to erasure coding are in the correct state at any given time.
- Fast Object Recovery
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The Fast Object Recovery service verifies unavailable objects and, if it finds that an object is available, changes the object status from unavailable to available.
- Garbage Collection
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The Garbage Collection service ensures that HCP storage doesn’t fill up with data that’s no longer needed.
- Geo-distributed Erasure Coding
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The Geo-distributed Erasure Coding service is responsible for ensuring that objects that are or have ever been subject to erasure coding are in the correct state at any given time.
- Migration
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The Migration service migrates data off selected storage nodes in either an HCP RAIN or SAIN system or off selected storage arrays in an HCP SAIN system in preparation for retiring those devices. During a data migration, the service copies objects and, if applicable, the metadata query engine index from the selected devices to free storage on the remaining devices. Before you start a data migration, you need to ensure that those devices have enough unused capacity to hold the data to be migrated.
After copying an object, the service deletes it from the source device.
- Migration Verification
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The Migration Verification service is responsible for verifying whether the Migration service encountered any errors with objects that should have been replicated. If the Migration Verification service encounters such an object, the service tries to migrate the object.
- Protection
- The Protection service ensures the stability of the repository by maintaining a specified level of data redundancy, called the data protection level (DPL), for each object in the repository throughout the entire object lifecycle. The DPL for an object is the number of copies of the object data that HCP must maintain.
- Replication
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The Replication service starts sending information on a link the first time you add HCP tenants and default-namespace directories to that link, as long as the link schedule has the service running at that time. If the service is not scheduled to run at that time, the service starts sending information as soon as the next scheduled run period starts.
- Replication Verification
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The Replication Verification service is responsible for verifying whether the Replication service missed replicating or cannot replicate any objects that should have been replicated. If the Replication Verification service encounters such an object, the service tries to replicate the object.
- Retirement
- The Retirement service restores the chunk for the object to a full copy of the object data on HCP systems where the object is not supposed to be metadata-only. It also deletes the chunk for the object on HCP systems where the object should be metadata-only. The service does not delete the chunk for an object until a full copy of the object data exists either on at least two systems in the topology or on one system if the object should have data on only one system.
- Scavenging
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The Scavenging service ensures that objects in the repository have valid metadata. When the service runs, it verifies that both the primary metadata for each object and the secondary metadata is complete, valid, and in sync with each other.
- Shredding
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The Shredding service shreds deleted objects that are marked for shredding. If the object is a multipart object, the Shredding service shreds each part of the object. The Shredding service also shreds unused parts of multipart uploads that began in namespaces where the default shred setting is True.
- Storage Tiering
- The Storage Tiering service performs these functions according to rules specified in service plans:
- Moving copies of the objects in a given namespace among all of the storage tiers that are defined for that namespace by its service plan.
- Creating and deleting copies of objects in a given namespace on each storage tier that’s defined for that namespace to ensure that each tier always contains the correct number of copies of each object.
- Changing objects stored on primary running storage to be metadata-only or restoring data to metadata-only objects.
- S Series Compression/Encryption Validation
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The S Series Compression/Encryption service compresses object data so as to make more efficient use of HCP storage space. The space reclaimed by compression can be used to store additional objects.