UC-2.4

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UC-2.4 Error Checking
Summary
Number	UC-2.4
Name	Error Checking
Context	UC-2 Archival Storage
Sub-Use Cases	None
Overview	Error Checking conducts error checks on AIP to ensure that no components of the AIP are corrupted during Archival Storage data transfers; Error Checking produces error logs that are checked by archives staff
Actors	Error Checking Manage Storage Hierarchy
Description
Preconditions	UC-2.1 Receipt of AIP
Triggers	Receive Data transfers the AIP to the archival storage volumes (Step 5 of UC-2.1) or Manage Storage Hierarchy assigns AIP to appropriate storage media based on storage management policies (Step 2 of UC-2.2) or Provide Data provides AIP or transfers to staging area (Step 2 of UC-2.6)
Successful outcome	Error Checking produces error logs and sends error logs to Manage Storage Hierarchy.
Steps	Error Checking conducts error checks on AIP (OAIS Page 4-8) Error Checking receives Data (notification of potential errors) from all hardware and software within the archive (OAIS Page 4-8) Error Checking produces error logs (OAIS Page 4-8) Error Checking sends error logs to Manage Storage Hierarchy (OAIS Figure 4-3:Functions of Archival Storage Page 4-7)
Exceptions
Documentation
Citations	OAIS page 4-8, section 4.1.1.3 "The Error Checking function provides statistically acceptable assurance that no components of the AIP are corrupted during any internal Archival Storage data transfer. This function requires that all hardware and software within the archive provide notification of potential errors and that these errors are routed to standard error logs that are checked by the Archival Storage staff. The PDI Fixity Information provides some assurance that the Content Information has not been altered as the AIP is moved and accessed. Similar information is needed to protect the PDI itself. A standard mechanism for tracking and verifying the validity of all data objects within the archive may also be used. For example, CRCs could be maintained for every individual data file. A higher level of service, such as Reed-Solomon coding to support combined error detection and correction, could also be provided. The storage facility procedures should provide for random verification of the integrity of data objects using CRCs or some other error checking mechanism."
Diagrams
Notes
	Triggers are different instances of internal data transfer. Do all these triggers count, or just this one: Manage Storage Hierarchy assigns AIP to appropriate storage media based on storage management policies (Step 2 of UC-2.2)?