Introduction

A popular request for Jira DC is the support for issue archiving which helps to speed up the performance of Jira. This article is to explain the different modes of archiving.
To avoid confusion between the 2, we will using the following naming convention

Issue Archiving - the archiving feature bundled with Jira Data Center
Issue Archiver - the Issue Archiver for Jira app

Simplified explanation

How Jira DC’s Issue Archiving works

When a project or issue is archived, it is being tagged so that it would be excluded in some screens and dropdown options. This prevent further changes to the project/issue.
The index entries of the archived issues will be deleted. Searching becomes faster with a smaller search index.

How Issue Archiver works

It generates a HTML file for each selected issues containing the fields and comments. The files are zipped up together with the attachments in an organised manner.

Comparison Table

Consideration	Issue Archiving	Issue Archiver

Consideration	Issue Archiving	Issue Archiver
Data Integrity	In some scenarios, it is possible for data to be modified after being archived. If some of the custom fields are deleted or options removed, the un-archived issues would lose the field values even after being unarchived.	This is definitely a point in time snapshot
Disk Storage	The data and attachments still reside within Jira. It is only hidden from view	The archives can be moved to another storage to free up disk space or as a secondary backup
Accessibility	This is a plus factor as the archived issues can be viewed directly from Jira	The archive can only be viewed by those who have access to the files. It can also be circulated to those who do not have access to the Jira server (e.g. external auditors, external project stakeholders)
Reversibility	It is possible to put the project back into Jira	It is not possible to reimport the archive back into Jira
Searchability	The issue can be searched by restoring and reindexing the archived project	It is not possible to search since this

Suitable Scenarios

Feature	Useful when

Feature	Useful when
Issue Archiving	You have sufficient disk space to store all the attachments You may need to work on the project again in future
Issue Archiver	You want to clean up the workflows and other schemes There is no future need to work on those archived projects. It is sufficient just to keep an offline backup of the issues You need to ensure a 100% point-in-time snapshot (due to regulatory requirements) You are concerned that Jira administrators might remove unused custom fields which can lead to some loss of data

Conclusion

It’s not easy to have a solution that addresses all the considerations. You can choose one that fits your needs or use a hybrid strategy to play safe.