I have a Backup to Disk folder (on a USB Drive) which does a full backup Monday through Saturday, inclusive. It runs at 23:00 each day, but the drive is only large enough to fit 5 backups. (Each backup is about 360GB, the drive 1.81TB.)

If I set the Overwrite protection policy to 1 day, by the time it gets to the Saturday backup, Monday's through Friday's backups are all overwriteable. How does BackupExec see this? Will it just overwrite anything from that selection, or will it still only overwrite the oldest? That is, will it overwrite Monday's, then when it runs again on Monday, will that overwrite last Tuesday's, then on Tuesday will that overwrite last Wednesday's etc.

Or is that not how it works?

If not, how can I set it up so that it does work like I have described above, keeping in mind I can only fit just 5 onto my drive?

I have a single job, all backing up to a single device called Back to Disk, and a single media set with OPP of 1 day. This is a client's setup, and as much as I imagine you will suggest it's awful practice the way I'm doing this, they don't want it changed, but just working so they don't need to delete the previous day's backup everyday so that it will append. (It is set to append first, then overwrite.)

  • Backup Exec places a Bit mask and a time stamp to identif the backup times and caluclates the oldest. – Zapto May 9 '12 at 18:38

Hope this helps... This is from the BackupExec 2010 help "About media overwrite protection" for "Rules specified in the media set": I bolded the important part for your situation.

Append period: The amount of time that data can be appended (added) to media. It is measured from the time the media was first allocated. It can be specified in hours, days, weeks, or years.

Overwrite protection period The amount of time that media is protected from being overwritten. It is measured from the time of the last write to the media, that is, at the end of the last append or overwrite job. It can be specified in hours, days, weeks, or years. When the overwrite protection period is over, the media becomes recyclable and can be overwritten.

The overwrite protection period begins when the backup job is completed. If there is an append period, the overwrite protection period begins again each time an append job completes. Because the overwrite protection period does not begin until the job completes, the amount of time that the job takes to complete affects the amount of time until the media can be overwritten. You may shorten the overwrite protection period to take into account the amount of time a job may run.

For example, setting the overwrite protection period for seven days and the append period for four days ensures that data will not be overwritten for at least seven days, and that data can be appended to the media for the next four days. The last data appended to this media is retained for at least seven days.

You will want to set the overwrite protection period for as long as you want the data backed up to be retained from the time the backup job completes. In your case I would set it to 4 days so the Saturday job still has the ability to overwrite the Monday job, but not overwrite the Tuesday job.

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