Question
How to choose IP migration scenario in Plesk?
Answer
Note: this is a description of migration planning step 4 of Plesk Migration guide. Steps 1-3 of the planning should be completed before choosing a scenario below.
To choose a scenario, check if new public IPs for the destination server are available.
If they are, choose scenario 1:
Scenario 1. Migration to new IPs
It is recommended to have the same amount if dedicated and shared IP on two servers, but this is optional. This scenario is recommended and used commonly. It is the safest for websites availability, causes minimal services downtime: the websites can be switched to the new IP one by one at any time when verified that they were migrated correctly.
- (optional) Decrease TTL for DNS zones to 1 hour or less (step #9 of this article). Low TTL value will allow clients to get the DNS updates faster.
- Perform migration to these IPs
- Verify how websites work locally on the destination server by adding the other IPs into the
hosts
- Point websites in DNS to the new IPs after migration.
- If DNS could not be switched for a domain for a long time, sync web/databases/mail data with the source server without starting full migration anew.
If there are no, or not enough additional public IPs for the destination server, choose one of scenarios below:
Scenarios 2. Migration to same IPs
Scenario 2a. Migration to same IPs using interim external IPs
- Have temporary internal (not routable) IPs on the destination server (same amount as on the source server)
- Migrate to these internal IPs
- Verify how websites work locally on the destination server by adding the internal IPs to the
hosts
- Remove the real IPs from the old server or shutdown it (to avoid IP conflict when we bring the IPs on the destination server online).
- Add the real IPs to the new server.
- Change IPs of Plesk subscriptions on the new server from temporary to the real.
This method is applicable if you do not have enough additional public IPs for the destination server to migrate to.
Another case is if there is a problem to switch DNS for most of the domains to the destination server IPs in a timely fashion (for example, domains’ DNS is hosted by different DNS providers and it takes a time to organize switching each one). This method requires services interruption between steps 4. and 5. (Switching subscriptions’ IP can take up to half an hour depending on the number of websites)
Scenario 2b. Migration to the same IPs with isolation
- Add same IPs on the destination server that are on the source but isolate them (avoid IP conflict by placing the IPs on the destination in a different VLAN or by blocking arp requests)
- Add two more different public IPs – one on the source (IP1) and one on the destination server (IP2)
- Perform migration of…
