migration sbs2003 to 2019

[elulto]

Hello everyone 

i have some project to do

on my customer site we have :

1. sbs 2003 with just this roles - dc+dhcp+dns+lot of shared folders (fileserver) (without exchange move 365)

2. another server 2012 r2 for second DC 

3 i create new 2 2019 servers 

what is the best way to migrate without lost all map users drive and demote sbs 2003 

thanks

[#2]

The two prerequisites to introducing the first 2019 domain controller are that domain functional level needs to be 2008 or higher and older sysvol FRS replication needs to have been migrated to DFSR
https://techcommunity.microsoft.com/t5/Storage-at-Microsoft/Streamlined-Migration-of-FRS-to-DFSR-SYS...

I'd use dcdiag / repadmin tools to verify health correcting all errors found before starting any operations. Then stand up the new 2019, patch it fully, license it, join existing domain, add active directory domain services, promote it also making it a GC (recommended), transfer FSMO roles over (optional), transfer pdc emulator role (optional), use dcdiag / repadmin tools to again verify health, when all is good you can decommission / demote old one.