• Glossary

Descriptions of terms used in the Netarchive software. The terms are listed in alphabetic order

Active Bit Preservation

• Active bit preservation means that the bits are actively monitored. Depending on the Quality of Service level this will give different requirements for the configuration of the archive in question. In the Danish installation of NetarchiveSuite we have the following configuration:

  • Two bitarchive locations representing copies of the data objects to be preserved (in order to be able to recover a bit error in a data object).
  • The two bitarchive locations are placed on separate physical locations (in order to have a copy in case of fire, floods, earth quake etc.).
  • One checksum location giving the number of three voting object locations (which is minimum number for the voting to make sense).
  To have a higher quality level for the active bit preservation more requirements will be needed.

• Please also refer to term Bitarchive Location.

• Please also refer to term Checksum Location.

• Please also refer to term Quality of Service Level.

• Please also refer to figure under term Repository.

ArcRepository

• Please refer to term Repository.

Bitarchive

• Very broad term that should be use with care since it can be used on many different levels. In princip a bitarchive is an archive of bits stored on some media.

• If possible it is preferable to use the terms like repository, bitarchive location and bitarchive instance.

Bitarchive Application

• Please refer to term Bitarchive Instance.

Bitarchive Instance

• A number of bitarchive instances are the representation of a bitarchive location. A bitarchive instance is an instance of the bitarchive software which can upload, run batch-jobs, correct or get-file/-record information for the represented part of the bitarchive location. In technical terms it is the instance that the NetacrchiveSuite bitarchive-application is running on. Note that this is not bound to be on one machine.

• Please also refer to figure under term Repository.

• Please also refer to term Bitarchive Location.

Bitarchive Location

• A bitarchive location is an object location in a repository containing the repository files as data objects.

• Please also refer to figure under term Repository.

• Please also refer to term Object Location.

Checksum Location

• A checksum location is an object location in a repository containing checksums of the repository files.

• Please also refer to figure under term Repository.

• Please also refer to term Object Location.

Development release

• Internal development release. Can be used for experiments.

Event harvest

• A selective harvest made at special events.

Full harvest

• See Snapshot harvest.

Object Location

• An object location is either a bitarchive location or a checksum location, i.e. either a location with a copy of repository data objects or a location with a copy of checksums of the Repository data objects. An object location will have one vote in voting on which object location is having the correct copy, as part of the active bit preservation.

• Please also refer to figure under term Repository.

• Please also refer to term Bitarchive Location.

• Please also refer to term Checksum Location.

Partial harvest

• See Selective harvest.

Physical Location

• A physical location is the geographical address or abbreviation indicating the geographical placement of for applications or object locations.

• Please also refer to figure under term Repository.

• Please also refer to term Object Location.

Quality of Service Level (of Active Bit Preservation)

• In the NetarchiveSuite the Quality of Service level can (or can in future) be regulated via different parameters, for instance:

  • Number of checksum algorithms used (future)
  • Distance between locations
  • Number of checksum locations (future)
  • Number of bitarchive locations
  • Time interval between checksum checks (future)
  • Quality of hardware

Release

• See Stable Release or Development release

Selective harvest

• A harvest of a few, selected sites that can be done repeatedly.

Snapshot harvest

• A limited-depth harvest of all domains known in the system. A snapshot harvest can only be run once, but can be based on an earlier snapshot harvest, harvesting only those domains that were not fully harvested in the previous harvest.

Stable Release

• Stable release of NetarchiveSuite SW.