Hello Charles Kincaid,

Some statements you made in your article are not entirely correct. The log backup chain does not start when you make the first database backup, it starts when you make the first log backup. The log starts to grow from the moment the database is created if you choose the full recovery model at creation time. The log also starts to grow the moment you switch from the simple recovery model to the full recovery model. The log file starts to grow as soon as the log does not fit in this file anymore, assuming that you did allow it to grow.

You don't need the most recent full backup to restore a database that uses the full recovery model, any full backup will do, as long as you still have all log backups available that were made after that full backup. A full backup replaces the entire log backup chain up to the time this full backup was made, when it comes to restoring your database. By the way, the same is true for a COPY_ONLY backup, there is no difference between an 'ordinary' full backup and a COPY_ONLY backup in this respect.

Then why do we need COPY_ONLY backups anyway? Because there is a third kind of backup that you did not mention in you article: the differential backup. A differential backup also replaces the log chain like the full backup, but when restoring a database, you always need the most recent full backup preceeding that differential backup to be able to use this differential backup. Things might go wrong if you take a full database backup outside the normal maintenance sequence. This full backup might not be available at the time of the (unplanned) restore and without you can not restore your differential backup you might rely on.

Certain backup tools (like BackUpExec) will always take the possibility of an intermediate differential backup into account. They need to make a full backup themselves to guarantee the usefulness of a potential differential backup, even if you don't use them yet. So they stop making log backups as soon as you made a full backup yourself outside the tool, for example to create a duplicate of a database on another SQL server instance. That's not a wise thing to do, because the log backups are still very useful if there is at least one full backup made with the tool, but that's just the way it is.

Using COPY_ONLY to avoid warning messages from these tools has nothing to do with the log backup chain, but everything with differential backups needing the most recent full backup. That makes your article still pretty relevant, because there are times you do need a COPY_ONLY backup, only for a different(ial) reason.