For I/O preserving reasons that aren't really relevant to the list, I've temporarily had my backup server on MaxBackups = 1 for a couple of weeks. I also have a backup client that is on a tightly restricted BlackoutPeriod of 8.0 through 23.9 (allowing backups from 23:59 through 08:00).
The combination of these two things has resulted in the blackout server never receiving an automatically queued backup for two straight weeks. We're back to regular MaxBackups now, and the other server will return to unrestricted hours soon, but I thought I'd bring this up in case there's a design problem with the scheduler that can be addressed. This is my guess about what's going on ... I assume someone in here knows more than I do about the scheduler and can correct or confirm my assumptions. When BackupPC does a wakeup it adds every host to the queue, and doesn't appear to apply any kind of sorting (is it explicitly random order?). When the server gets under MaxBackups and decides to start a new backup, it appears to iterate over the current queue in the order listed, discarding hosts that are not due for backups at all as it finds them. The first host it finds that is due for a backup of any kind, it starts the backup and removes that host from the queue. If it encounters a host that is due for backup but in blackout, it discards/removes that host as if it were not due for backup. The end result is that a server that has a blackout period might never get a backup, because the server will only execute a backup for it if, outside of its blackout period, there are no servers ahead of it in the queue that are due for backup. The problem does not require that there be too many backups to complete in a single BackupNightlyPeriod. All it needs is for there to be enough servers for there to be a low probability of a server with a blackout period randomly appearing near the top of the queue outside its blackout hours. Assuming I'm right about the mechanisms in play, there are two fixes I can think of (one can be changed in two places): 1a. hosts are added to the queue in reverse order of their "Last Backup (days)" value from the Host Summary (larger numbers first). 1b. backuppc processes the queue in Last Backup order, larger numbers first. 2. when picking from the queue, hosts that are due for backup but in blackout are skipped without being removed, leaving them in their queue position Thoughts? Am I completely off base?
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