RHEL 8.x Spectrum Protect Theory

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Device class

The type of storage device that can use the volumes that are defined in a sequential-access or random-access storage pool. Each device class of removable media type is associated with a single library.

DISK device class

In a DISK device type of storage pool, data is stored in random access disk blocks. You can use caching in DISK storage pools to increase client restore performance with some limitations on server processing. Space allocation and tracking by blocks uses more database storage space and requires more processing power than allocation and tracking by volume.

FILE device class

In a FILE device type of storage pool, files are stored in sequential volumes for better sequential performance than for storage in disk blocks. To the server, these files have the characteristics of a tape volume so that this type of storage pool is better suited for migration to tape. FILE volumes are useful for electronic vaulting, where data is transferred electronically to a remote site rather than by physical shipment of tape. In general, this type of storage pool is preferred over DISK storage pools.

Storage pool

A set of storage volumes or containers that is the destination that is used to store client data. IBM Spectrum Protect uses the following types of storage pool:

• Directory-container storage pools
• Cloud-container storage pools
• Sequential-access storage pools that are associated with a device class
• Random-access storage pools that are associated with a device class

Policy domain

The policy domain is the primary organizational method of grouping client nodes that share common rules for data management. Although a client node can be defined to more than one server, the client node can be defined to only one policy domain on each server.

Policy set

A policy set is a number of policies that are grouped so that the policy for the client nodes in the domain can be activated or deactivated as required. An administrator uses a policy set to implement different management classes based on business and user needs. A policy domain can contain multiple policy sets, but only one policy set can be active in the domain. Each policy set contains a default management class and any number of extra management classes.

Management class

A management class is a policy object that you can bind to each category of data to specify how the server manages the data. There can be one or more management classes. One management class is assigned to be the default management class that is used by clients unless they specifically override the default to use a specific management class.

The management class can contain a backup copy group, an archive copy group, and space management attributes. A copy group determines how the server manages backup versions or archived copies of the file. The space management attributes determine whether the file is eligible for migration by the space manager client to server storage, and under what conditions the file is migrated.

Copy group

A copy group is a set of attributes in a management class that controls the following factors:

• Where the server stores versions of backed up files or archive copies
• How long the server keeps versions of backed up files or archive copies
• How many versions of backup copies are retained
• What method to use to generate versions of backed up files or archive copies

Types of data protection services

a. Back up and restore services:

You run a backup process to create a copy of a data object that can be used for recovery if the original data object is lost. A data object can be a file, a directory, or a user-defined data object, such as a database.

To minimise the use of system resources during the backup operation, IBM Spectrum Protect uses the progressive incremental backup method. For this backup method, a first full backup of all data objects is created and in subsequent backup operations only changed data is moved to storage. Compared to incremental and differential backup methods that require taking periodic full backups, the progressive incremental backup method provides the following benefits:

• Reduces data redundancy
• Uses less network bandwidth
• Requires less storage pool space

To further reduce storage capacity requirements and network bandwidth usage, IBM Spectrum Protect includes data deduplication for data backups. The data deduplication technique removes duplicate data extents from backups.

You run a restore process to copy an object from a storage pool to the client. You can restore a single file, all files in a directory, or all of the data on a computer.

b. Archive and retrieve services

You use the archive service to preserve data that must be stored for a long time, such as for regulatory compliance. The archive service provides the following features:

• When you archive data, you specify how long the data must be stored.
• You can request that files and directories are copied to long-term storage on media. For example, you might choose to store this data on a tape device, which can reduce the cost of storage.
• You can specify that the original files are erased from the client after the files are archived.

The retrieve service provides the following features:

• When you retrieve data, the data is copied from a storage pool to a client node.
• The retrieve operation does not affect the archive copy in the storage pool.

c. Migrate and recall services

You use migrate and recall services to manage space on client systems. The goal of space management is to maximise available media capacity for new data and to minimise access time to data. You can migrate data to server storage to maintain sufficient free storage space on a local file system. You can store migrated data in the following ways:

• On disk storage for long-term storage
• In a virtual tape library (VTL) for fast recall of files

You can recall files to the client node on demand, either automatically or selectively.

Ref: https://www.ibm.com/docs/en/SSEQVQ_8.1.5/srv.solutions/b_srv_concepts_guide.pdf

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