What are the common migration strategies?
Big Bang Migration:
A single pass migration strategy that will move the entire mailbox in one pass after MX records are cutover.
A typical scenario consists in cutting over on a Friday evening and migrating during the weekend.
Pros:
Cost-effective.
Simplest to implement.
Cons:
Migration may potentially not complete in time for various reasons.
Users accessing the new system may not have access to all their data when work resumes.
Any items created during or after the migration may be missed by a single pass.
Downtime may occur for some users if migration fails or takes too long.
Pre-Stage Migration:
A multi-pass migration consists of pre-staging a majority of the data prior to cutover and doing a Full (Delta) Pass after cutover.
Pros:
Majority of data is available at time of cutover.
Mitigate migration risks in which the majority of data will be available regardless of availability of source server at time of cutover.
Cons:
Will not propagate updates, deletes, or moves of the items previously migrated in the first migration pass.
How do I configure a multi-pass migration?
Quick-Switch Migration
A quick-switch migration consists of pre-staging only the newest emails. New emails are accessible immediately at time of cutover by users and the remaining data is backfilled over time.
Pros:
Initial migration is quick.
Time between cutover and data availability is short.
Cons:
Not all data is available at time of cutover for end users.
How do I configure a Quick-Switch Migration?: https://bittitan.zendesk.com/hc/en-us/articles/115008250448