Copying index snapshots between Data Center nodes should be faster

Problem

Data Center nodes can ask another node to provide a full index snapshot when:

1. A new node is started and has no index
2. Index replication has fallen sufficiently far behind
3. The copy request has been triggered manually

Currently, this can take upwards of an hour, making the node where the index is broken or missing unusable. The chief contributor to this is the time it takes to zip the index, and this can be shortened by using a faster compression algorithm as long as the I/O device used for shared storage is fast enough.

Suggested fix

• The compression method used can be configured with the jira.index.snapshot.copy.archiver application property.
• Format: jira.index.snapshot.copy.archiver=(snappy|zip|tar)
• setting the jira.index.snapshot.copy.archiver application property to zip will revert to the old behavior.