11.2.0.4 DB on Oracle Linux 6.5
We have a DB whose archive generation is as follows.
Average Archive Log generation: 400 GB/day
Max log generation : 900 GB/day
Archive Log diskgroup size: 4TB
Backup strategy: We take full backups on Monday and Wednesday and Level1 for the rest of the days.
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Sunday --> Level 0 backup
Monday --> Level 1 backup
Tuesday--> Level 1 backup
Wednesday--> Level 0 backup
Thursday--> Level 1 backup
Friday--> Level 1 backup
Saturday--> Level 1 backup
Both Level0 and Level1 scripts have PLUS ARCHIVELOG ; (without DELETE ALL INPUT clause)
We have archiveLog backup script which runs at 10AM and 4PM which doesn't do DELETE ALL INPUT either.
We purge the archivelogs from Level0 and Level1 backup scripts, with the following command
delete noprompt archivelog until time 'SYSDATE-2';
Question1. What is the industry standard of keeping (retention period) the archive logs within DB ? Is there a 'formula'/rule of thumb for this ? In case of restore,recover we don't waste much time restoring archivelogs from backup media. That is why we are keeping 2 days of archivelog within the DB now.
Question2. We have 4TB of space to store archivelogs in this particular DB. With 900GB Max daily arch Logs generation we can safely keep last 3 days of archivelogs . Right ? I mean, is there a possibility of hitting the dreadful archiver error if we increase the retention period of archive logs using delete noprompt archivelog until time 'SYSDATE-3';