Editing Tornedo.tetrain.com Upgrade Plan (section)

== 2. Precision note on 'in-place to CentOS Stream 10' — read this before scheduling ==

There is '''no single-hop tool path from CentOS Linux 7 straight to CentOS Stream 10.''' <code><nowiki>leapp</nowiki></code> (the only real in-place conversion mechanism for this OS family) only supports one major version at a time, and each hop requires its own compatible leapp release/actors. To reach Stream 10 in place, this is actually '''three chained conversions''', each a separate maintenance event with its own reboot and validation pass:

<pre>
<nowiki>
CentOS Linux 7  --[ELevate/leapp, target=centos]-->  CentOS Stream 8
CentOS Stream 8 --[leapp]-->                          CentOS Stream 9
CentOS Stream 9 --[leapp]-->                          CentOS Stream 10
</nowiki>
</pre>

Two things this changes about how risky this is compared to a normal single-hop hobbyists:

* '''This is not a commonly documented/validated path for a domain controller.''' Red Hat/leapp guidance is written and tested around one hop (N→N+1) on general-purpose servers. Chaining three major-version conversions on a live Kerberos KDC + LDAP directory + PKI CA is well outside the normal-case documentation, and each hop's <code><nowiki>ipa-server-upgrade</nowiki></code> (which runs automatically post-conversion) has to succeed cleanly before the next hop is safe to attempt.
* '''CentOS Stream is a rolling upstream branch, not a stable point release''' — it receives updates ahead of RHEL, which is a materially different stability/change profile than Rocky/AlmaLinux for a service this sensitive to schema/version compatibility (LDAP, Kerberos, and Dogtag PKI all have on-disk/protocol formats that change across majors). Worth a deliberate call, not a side effect of picking Stream — flagging in case Rocky/Alma 10 (same RHEL-family lineage, stable point release) is actually what's wanted and "Stream" was shorthand rather than a specific choice.

Since there's no replica/fallback host in this approach, the safety net has to come from backups and (if the box is virtualized) snapshots, taken '''before every single hop''', not just once at the start.