Log shipping will not break the log chain. But possibly the maintenance plans could break the log chain for the log shipping, in a way, although I don't know the internals to tell. In any case, if you set up log shipping you probably want to coordinate the log shipping with your maintenance plans.
Here are a couple of ways to break your log chain:
* Flip the recovery mode to Simple and back.
* BACKUP LOG with NO_LOG or TRUNCATE_ONLY (in SQL 2005 and earlier only)
* Overwrite a log-backup.
* Deleting a file with a log backup.
* Forgetting where you have a file log backup.
I don't know exactly how log shipping traces the log files, but possibly if you take a log backup outside the log-shipping schedule, log shipping would miss that log, and would not be able to apply the next log on the standby server.
I need to admit that I am quite out on a limb here. My profile is more of a developer than an operational DBA. While I have some knowledge about how log backups, log-shipping etc works, I don't have that much practical experience. But since this forum is for T-SQL questions, this is also what you can expect here.
The people in the Database Engine forum might be able to give you more precise answers.
Erland Sommarskog, SQL Server MVP, esquel@sommarskog.se
