Best way to move sites from one cpanel to another with minial downtime

Yes, backup and restore is the safest option, but here are a few checks.

1- To minimize downtime for your sites during IP change from reseller to dedicated, reduce the TTL value in the DNS zones of your sites on the reseller to a very low value a couple of days before transfer or equivalent time of the current TTL value. You can do so from "WHM >> DNS Functions >> Edit DNS zone."

2- Log in to your dedicated WHM and go to "Transfers >> Copy multiple accounts/packages from another server", or you can use the individual account transfer feature. These are pretty self-explanatory and easy to use.

3- Once all accounts have been restored on the dedicated, you can change DNS to point everything to dedicated.

4- On destination, you can again increase the TTL value of the sites to the original value on the reseller after everything is propagating from the dedicated.

 

I would have migrated the following way:

1. Migrate the website from Reseller account to Dedicated server using the "Transfers >> Copy multiple accounts/packages from another server" option on the Dedicated server.

2. As soon as a domain is migrated over to the Dedicated server, edit the DNS zone of the domain on the Reseller account from "WHM >> DNS Functions >> Edit DNS zone" and change the A record of the website from old server IP to the Dedicated server IP.

3. Assign the new name servers to the domain at the domain registrar end.

The 2nd step will make sure that the website will work from the dedicated server even if the request come to the reseller account. And once the name servers are updated, the requests will directly come to the dedicated server.

This will minimize the downtime and you are free to terminate the domain from the reseller account within 24 hours of changing the name servers.

 

Which are the DNS records that should have a lower TTL? I have personally lowered all A TTLs and after the data copy I intend to change the IPs for all A records (and after that the IPs for the nameservers). Should I lower any other TTL besides A records?

 

You may want to lower MX TTL as well. I would recommend uniformly reducing TTL values for all records. You do not want mails delivering to the old server during the DNS propagation period.

 

If you select "Express Transfer" then this is done automatically.

 

So A and MX. I leave all the rest untouched...SOA values, NS, CNAME etc. Right?

One problem with this is that I believe you have to select it individually from that list and I have close to 1000 accounts.

 

No -- there's a checkbox at the top to select all the accounts for express transfer.