I wrote a short article on enabling and disabling trace flags. You can read it, but I didn’t really discuss the implications of session v global trace flags, which is something I’d like to do here.
In the article, I set trace flag 3226 for my session. This showed that a second backup wasn’t in the error log. Note the image below doesn’t have a backup message after (above) the trace flag change entry. You’ll have to trust me that I ran the backup, enabled the traceflag, and then re-ran the backup to get this image.
However, if I have a backup job, as I do here, does the trace flag affect this? This is, after all, run by SQL Agent, which would be a different session.
It turns out that the session trace flag doesn’t affect this. I ran the backup job and there was a message in the error log.
To suppress this, I’d have to use DBCC TRACEON (3226, –1) or put this in the startup parameters to ensure none of these messages appear.