To transfer all of your accounts to a new server, you'll need to follow a few steps.
1) First, you'll need to install DA on the new server. Create another license in your Client Account. Once created, contact sales@directadmin.com to activate the license for a short period of time while you do the transfer. Install DirectAdmin on the new server as a default install. Goto step 2. Once the transfer is complete, email sales@directadmin.com again to delete that license, and to put the new IP into the old license. Once that's set, then update your new server to use the old license: How to update License.
2) For each IP that you are using on the old server, you'll need to add new IP's to the new server. Plan out which IP's will match up. Go to Admin Panel -> IP Manager on the new server, and add all of the IP's. You can change the IP assignment of the user when doing the transfer. Eg: If they are currently on an owned IP address, it's quite easy to transfer everyone to a shared IP address, so If you don't have as many IP's, that's not a problem. Similarly, you can add users to owned IP's if they were shared on the old server.
3) For each Admin/Reseller account on the old system, they will have to be create through DA the usual way on the new system (does not apply if you're using Admin Backup/Transfer). If the User backup files of the Reseller/Admin (their personal user files) were just restored, their account would be created as a user. This is why their account needs to be first created. Once each Reseller/Admin are created, go to Admin Panel -> IP Manager and assign each one whichever IP's they'll need to be using.
4) On the old server, for each Admin/Reseller, login as them, and go to their Reseller Panel -> Manage User Backups. Select all accounts, and make a local backup of those accounts. We recommend doing a local backup and then transferring the files over to the new server by hand. You can try to use the ftp feature to upload to the same Admin Reseller on the new server, but you'll have to make sure the firewalls are setup correctly first. (try it and make sure the files exract properly before doing all accounts). When uploading the backup files to the new server, place them in /home/reseller/user_backups. Where reselleris the name of the admin/reseller who owns those accounts (including his own personal file). Make sure that the user_backups directory is owned by that admin/reseller and that the backup files in that directory are chmod to 755 (needs to be readable by the user who is being restored).
The newer alternative for the Reseller Level Backups is Admin Level -> Admin Backups/Transfers. It's essentially the same thing, except the file naming is slightly different and it can all be done from one screen (no extra logins required), and you can skip step 6 as Reseller Level settings are included in this system. Restore the Admins and Resellers first. (Admin Backups/Transfers also creates Reseller *as* Resellers, not users, so there is no need to create an empty template account first, the restore does it all for you).
5) On the new server, for each Admin/Reseller, login and go to Reseller Panel -> Manage User backups. For all accounts shown in the list, restore them. If you are assigning different users to different IP addresses, you'll have to do 1 restore per IP with which ever user(s) you are restoring. Eg: if 5 users are going to 1 shared IP, select those 5 users, select the shared IP and restore them. (Make sure you set that IP to be "shared" in the Reseller Panel -> IP Assignments first.). If you are restoring 1 user to his own shared IP, he'll have to be restored by himself without any other users. Repeat the restore process for all users until complete. When restoring Admin/Reseller user accounts, the IP selection doesn't matter as their user account is already created.
6) The restore process for Reseller Level settings will have to be copied manually. To copy the Reseller's packages over, copy the contents of /usr/local/directadmin/data/users/reseller/packages/* and /usr/local/directadmin/data/users/reseller/packages.list over to the new server with the same settings. The reseller will also have to setup any nameserver settings again. (dns info isn't restored), so make sure that the default nameservers are set in the Reseller Panel -> Nameservers before restoring the users.