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If you backup the database with a Level 0 every six hours, then do the archive logs in between, every 15 minutes perhaps, what benefit would I have to incorporating a differential backup? Essentially, full backup only with archive logs x minutes. Particularly cumulative. Is it only because of disk space?

I have read this,

Is it enough to have only full backup and transaction log backup only for a good backup plan?

But it did not help, as it includes a differential.

Edit: I ask because I thought you had to have a full backup to use a differential in the first place. So why not just have the full backup to begin with?

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  • What do you mean "it didn't help"? It explained the principles - and in this case, even though they were addressing MSSQL, the principles are the same. If you understand the principles you should be able to judge for yourself if your proposed/present strategy is "bad". What kind of answer are you looking for?
    – EdStevens
    Commented Dec 18, 2018 at 22:19
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    If you can comfortably store multiple full backups, if the restore time is acceptable and the resources required while the backup is running is acceptable you can stick with this simple scheme. Simple is good.
    – eckes
    Commented Dec 19, 2018 at 0:32
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    Bit basically a full backup done very often would result in the fastest restore time, so if this works for you do it.
    – eckes
    Commented Dec 20, 2018 at 13:14
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    @eckes You should put an answer. I would mark it correct. But I think you can't now.
    – johnny
    Commented Dec 20, 2018 at 15:25
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    Technically you don't need anything but full bkup + archlogs, but for fastest recovery you don't want to rely solely on archlogs. After restoration of db from full bkup, recovery will begin with any available inc-1 backups. When those are exhausted it will continue with archlogs but in general recovery from archlogs is slower than from inc bkups. In the end the only 'bad' strategy is one that fails to meet recovery requirements. But some are less efficient than others.
    – EdStevens
    Commented Dec 20, 2018 at 22:54

3 Answers 3

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Do you have enterprise edition or standard edition? If you have enterprise edition you can create a block change file and do a true level 1 incremental backup. Doing a level 0 backup is a FULL backup. There is not reason for you to do a FULL backup every 6 hours. Most people do a FULL backup every day and possibly send the archive logs to more than one server. I do two level 0 backups per week and level 1 backups on the days when I am not doing a level 0 backup. If you are new to Oracle you may want to do a backup/recovery class. You should practice backup and recovery on development databases.

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  • But why is it bad to do the full backup and archive logs? That's what I don't get.
    – johnny
    Commented Dec 19, 2018 at 14:57
  • You don't need 4 full backups per day. You should probably specify the size of your database and the longest time that you can wait for a restore. It might also help to know what edition of Oracle you use, number of cores and amount of RAM. As others have stated, you do the backup so that you can recover if needed.
    – Gandolf989
    Commented Dec 19, 2018 at 20:25
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IMHO, you're asking the wrong question.

What are your Recovery Point and Recovery Time Objectives? (That is: how quickly do you need to get the database back after a critical failure and how much data are you prepared to lose in doing so?)

Get those answers nailed down (and that's not solely your decision, by the way; it needs to come from your Organisation) and then you can start worrying about how to achieve those objectives and, from that, the kinds of backups you're going to need.

Remember - you're implementing a Recovery Strategy; backups are just a way to deliver that.

After all:

Backups are a complete waste of time and effort ... until you've completed a Recovery that uses them.

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The most important question is: Why are the backups done the way they are done? Are there special reasons for takeing full backups every six hours?

You can do - depending on your database edition - a lot of backup strategies. The best method depends on your Environment. How big is your DB? Do you want fast backups or quick restores? Depending on these answers you can decide if incremental backups are a benefit.

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