Upgrading a Samba AD DC

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Run the following steps when you are updating a Samba Active Directory (AD) domain controller (DC). For a Samba NT4-style PDC, a Samba domain member, or a standalone installation, please see updating samba.

In-place upgrades

  • Stop all Samba services.
  • Install the latest packages over your existing ones.
  • Start the samba daemon.
  • Check your Samba log files for errors.
  • Test your updated installation, e.g. verify users can login successfully.

Updating Multiple Samba Domain Controllers

If you are updating multiple Samba AD DCs, it's recommended to mitigate the risk of data loss by following this process:

  • Update one Samba AD DC that does not hold any flexible single master operations (FSMO) role, or else the DC with the least roles.
    • For upgrading to a new minor release, simply use the 'in-place upgrade' steps above.
    • For upgrading to a new major release, we recommend using the 'DC rejoin' steps below.
  • Start Samba on the updated DC.
  • Verify that the directory replication between all DCs is working correctly:
# samba-tool drs showrepl
  • Test the installation to ensure that the new version works correctly.
  • Upgrade all other Samba DCs one at a time, with those holding FSMO roles last, and always verify that the replication is working correctly.

This method ensures that if any of the DCs have issues with the new version, you can find out with a joined DC rather than the master. If the issue can't be fixed easily, you can return to an earlier version on the joined DC without network downtime or risk of data loss.

DC rejoin

  • Stop all Samba services.
  • Install the latest packages over your existing ones.
  • Run the samba-tool domain join <realm> dc command to rejoin the upgraded DC to the domain. This uses DRS replication to completely rebuild the DC's local database. Try to use the same command options as you did when you originally joined the DC.
  • Start the samba daemon.
  • Check your Samba log files for errors.
  • Test your updated installation, e.g. verify users can login successfully.

Downgrading

If the master (or some DC with an FSMO role) was upgraded and must be downgraded again, please read Downgrading an Active Directory DC.


Samba AD DC Database Check

The samba-tool utility enables you to detect and fix problems in the Samba Active Directory (AD) database. For example, if a previous Samba version stored an attribute incorrectly and the updated version fixes the problem. You must run the check and fix command on every Samba AD DC locally, because some fixes apply to non-replicated attributes and modifications are not replicated to other DCs.

To check the AD database, run: 

# samba-tool dbcheck --cross-ncs

To fix reported errors, run: 

# samba-tool dbcheck --cross-ncs --fix

If you pass the --yes parameter to the command, all questions are automatically answered with yes. Note that if you omit the --yes parameter, the database check executes three fsync() calls for each object. This can result in a longer run duration. For example, passing the --yes parameter to the command fixed 3500 objects in 10 seconds in our test environment. Without this parameter, the command required 4:50 minutes for the same operation.

After a repair, re-check the database to verify a successful operation.

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