14
Data Migration Cutover
Data Migration Cutover
1
2027-01-04T08:00:00
2027-03-04T08:00:00
1
08:00:00
17:00:00
7
0
0
1
Standard
1
-1
1
0
2
1
08:00:00
12:00:00
13:00:00
17:00:00
3
1
08:00:00
12:00:00
13:00:00
17:00:00
4
1
08:00:00
12:00:00
13:00:00
17:00:00
5
1
08:00:00
12:00:00
13:00:00
17:00:00
6
1
08:00:00
12:00:00
13:00:00
17:00:00
7
0
1
1
Discovery
1
0
1
1
500
2027-01-04T08:00:00
2027-01-13T17:00:00
PT64H0M0S
7
0
0
1
0
168000
0
0
2
2
Inventory the source estate
1
0
1.1
2
700
2027-01-04T08:00:00
2027-01-08T17:00:00
PT40H0M0S
7
0
0
0
0
182400
0
4
2027-01-04T08:00:00
Site collections, mailboxes, file shares, group memberships. Record volume in GB and item counts, both matter to throughput.
3
3
Name a data owner for every workload
1
0
1.2
2
500
2027-01-06T08:00:00
2027-01-08T17:00:00
PT24H0M0S
7
0
0
0
0
182400
0
4
2027-01-06T08:00:00
One accountable owner per site, share or mailbox group. Unowned data is what stalls a wave.
4
4
Record baseline counts for reconciliation
1
0
1.3
2
700
2027-01-11T08:00:00
2027-01-11T17:00:00
PT8H0M0S
7
0
0
0
0
177600
0
4
2027-01-11T08:00:00
Item counts and totals per workload, captured before anything moves. You cannot reconcile against a number you did not take.
5
5
Agree what does not move
1
0
1.4
2
500
2027-01-11T08:00:00
2027-01-13T17:00:00
PT24H0M0S
7
0
0
0
0
168000
0
4
2027-01-11T08:00:00
Archive, leave in place, or delete. Every GB ruled out here is throughput you get back later.
6
6
Design
1
0
2
1
500
2027-01-14T08:00:00
2027-01-22T17:00:00
PT56H0M0S
7
0
0
1
0
134400
0
0
7
7
Map identities and group membership
1
0
2.1
2
700
2027-01-14T08:00:00
2027-01-18T17:00:00
PT24H0M0S
7
0
0
0
0
153600
0
4
2027-01-14T08:00:00
Source accounts and groups to target accounts and groups, including the ones that will not exist on the other side.
8
8
Map permissions, and decide where inheritance breaks
1
0
2.2
2
700
2027-01-18T08:00:00
2027-01-20T17:00:00
PT24H0M0S
7
0
0
0
0
144000
0
4
2027-01-18T08:00:00
Broken inheritance and per-item permissions rarely survive intact. Decide now which are recreated and which are dropped.
9
9
Choose the tooling and prove throughput
1
0
2.3
2
700
2027-01-19T08:00:00
2027-01-22T17:00:00
PT32H0M0S
7
0
0
0
0
134400
0
4
2027-01-19T08:00:00
Measure GB per hour against the live target, not a lab. Throttling is the number every wave plan depends on.
10
10
Pilot
1
0
3
1
500
2027-01-25T08:00:00
2027-02-01T08:00:00
PT40H0M0S
7
0
0
1
0
110400
0
0
11
11
Run a pilot wave with one willing team
1
0
3.1
2
700
2027-01-25T08:00:00
2027-01-27T17:00:00
PT24H0M0S
7
0
0
0
0
120000
0
4
2027-01-25T08:00:00
A team that will tell you what broke. Small enough to redo, representative enough to learn from.
12
12
Reconcile the pilot against the baseline
1
0
3.2
2
700
2027-01-28T08:00:00
2027-01-29T17:00:00
PT16H0M0S
7
0
0
0
0
110400
0
4
2027-01-28T08:00:00
Item counts, permissions, and a sample opened by a real user. Sign-off is the gate to wave 1.
13
13
Write the user comms and the rollback note
1
0
3.3
2
500
2027-01-29T08:00:00
2027-01-29T17:00:00
PT8H0M0S
7
0
0
0
0
110400
0
4
2027-01-29T08:00:00
What changes, when, what to do if it looks wrong, and what the rollback actually is. Send before the wave, not during it.
14
14
Pilot signed off
1
0
3.4
2
500
2027-02-01T08:00:00
2027-02-01T08:00:00
PT0H0M0S
7
0
1
0
0
110400
0
4
2027-02-01T08:00:00
15
15
Waves
1
0
4
1
500
2027-02-03T08:00:00
2027-02-19T08:00:00
PT96H0M0S
7
0
0
1
0
43200
0
0
16
16
Migrate in waves by owner, not by volume
1
0
4.1
2
700
2027-02-03T08:00:00
2027-02-16T17:00:00
PT80H0M0S
7
0
0
0
0
52800
0
4
2027-02-03T08:00:00
Group a wave around people who work together, so a half-migrated team is never trying to share a file across the boundary.
17
17
Run delta syncs behind each wave
1
0
4.2
2
700
2027-02-08T08:00:00
2027-02-16T17:00:00
PT56H0M0S
7
0
0
0
0
52800
0
4
2027-02-08T08:00:00
Source stays live during coexistence, so everything already moved keeps changing. Delta until the final pass is small.
18
18
All waves migrated
1
0
4.3
2
500
2027-02-19T08:00:00
2027-02-19T08:00:00
PT0H0M0S
7
0
1
0
0
43200
0
4
2027-02-19T08:00:00
19
19
Cutover
1
0
5
1
500
2027-02-25T08:00:00
2027-03-04T08:00:00
PT40H0M0S
7
0
0
1
1
0
0
0
20
20
Final delta, then switch the endpoint
1
0
5.1
2
900
2027-02-25T08:00:00
2027-02-26T17:00:00
PT16H0M0S
7
0
0
0
0
14400
0
4
2027-02-25T08:00:00
Freeze the source, run the last delta, then move DNS, MX or the mapped drive. The switch is the cheap part if the delta is small.
21
21
Production cutover
1
0
5.2
2
500
2027-03-01T08:00:00
2027-03-01T08:00:00
PT0H0M0S
7
0
1
0
0
14400
0
4
2027-03-01T08:00:00
22
22
Decommission the source and reclaim licences
1
0
5.3
2
500
2027-03-01T08:00:00
2027-03-03T17:00:00
PT24H0M0S
7
0
0
0
1
0
0
4
2027-03-01T08:00:00
Read-only first, then decommission on a date you announced. Licences and storage are the savings the business was promised.
23
23
Source decommissioned
1
0
5.4
2
500
2027-03-04T08:00:00
2027-03-04T08:00:00
PT0H0M0S
7
0
1
0
1
0
0
4
2027-03-04T08:00:00