I'm struggling with the backup life settings for my data sets on disk.
I can't get this to work properly; either jobs are purged from disk which shouldn't have or jobs are still on disk while they should be purged.
For example I often see that there are daily jobs on disk but without the preceding full job. So these daily jobs are useless to keep on disk.
So I'm wondering what other users have for backup life settings; based on full backup count or based on time or both, with or without force expiry.
Full backup runs on Friday night = weekly backup
Incremental backup runs on Monday-Thursday night = daily backup
Backup is disk > disk > tape, used tapes are taken home each night.
I can divide the data on disk in 2 groups :
Group 1 - my file server: I want to be able to restore data from disk up to 2 weeks old. This server has it's own 'advanced backup options' for daily and weekly jobs.
Group 2 - all other servers: it is enough to restore data from disk up to 1 week old. These servers all use the same 'advanced backup options'.
On Tuesday Jan 10th, I want to restore a file from a server in group 2 from Wednesday Jan 4th.
To use the daily jobs from Wednesday Jan 4th, I would need the preceding full backup from Friday Dec 30th as well. So I would need to have 2 full backup sets on disk to be able to restore data from 1 week old, full backup from Friday Dec 30th + full backup from Friday Jan 6th. Correct?
In your opinion, what would be the correct backup life settings to accomplish this (both for the daily and weekly jobs) ?
Expiration requirements are dependent on more requirements than it may seem from the options description when configuring the retention in the 'Advanced Options Set'. For example, If you set both Discard After Full Backup Count and Discard After options for a Full Backup, the backup is retired only when both conditions are met. For example, if you set the Discard After Full Backup Count option to four Full Backups and the Discard After option to 30 days, the backup is retired after four Full Backup counts and 30 days.
If any dependent Incremental or Differential Backups exist for a backup, the backup is not retired until all dependent backups have reached their retirement date.
NOTE: When you set time-based retirement, the time component (HH:MM) is automatically set to the job save or job submit time.
NOTE: In time-based retirement, the time component (HH:MM) does not represent the actual retirement time. It only represents the time due for backup retirement. The actual time of retirement is determined by the interval at which Media Manager scans the Media Database to identify the backups that it needs to retire. The default interval between two scans is 60 minutes. Thus, if the retirement time is set to 10:20, the backup is actually retired at 11:00.
To understand this better, please see this brief section from the NetVault Backup 11.x Administration Guide under "Backup Indexes." This section will explain what you are seeing, which is basically, that retirement is reached when the retention period is met for all backups, even in an incremental sequence. Granted, the incrementals for a retired full may be rendered useless, but they still reside on disk, but the retention for the last incremental in that set must be expired before they are purged and overwritten.
To answer your last question, if you were trying to restore data from Wednesday Jan. 4th, you are correct, you would need the Full from Dec. 30th. Basically, when it comes to retiring backups vs. restorability, you always want to make sure you keep retention as long as you need to restore from. So, if you have more recent restore needs, you will need to ensure you have restorability from the some means such as you have with Disk, and then have other means, such as you have with tape, for your longer retention or archival needs. If the timeframe for restore runs out on the disk copy, you need to recall from tape.
I don't see anything wrong with how you have it currently, and you could not necessarily change it to free up space if you needed to recover data from disk from a backup over 2 weeks old. I would say the most common retention period setting people use would still be the 30 day retention at least, unless they were slim on disk based storage or something to that effect - and we do see more people use a Time Based Retention rather than Generation Based (discard after full backup count.)