Déjà Dup

Delete Old Backups!

Asked by Vanessa

Hi,

I am also using Ubuntu 11.10 with Deja Dup, and backing up to a cloud service. The functionality that I want is to backup every day, and delete backups that are over a week old, so at any given point I should have a total of seven backups. I specified to "keep backups at least a week," however I now have backups from the last two weeks, and they keep adding up!

I logged into my cloud service to see if it was a big deal to delete them manually... and it IS... each one is hundreds of difftar.gpg files that would take considerable time to even delete one instance. That does not seem like a feasible option to me.

Could you please help me figure out how to automate the deletions?

Many thanks,

Vanessa

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Michael Terry
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Revision history for this message
Michael Terry (mterry) said : 		#1

So Deja Dup always makes sure to have two full backups. It has its own logic that is sometimes at odds with the "Keep backups" setting. That setting carefully says "at least", meaning it specifies a minimum amount of time. Deja Dup sometimes holds on to data for longer.

But looking at its logic now, I see that it will make a new full backup no sooner than each month. I'm realizing this would be the sequence:

1) First backup
2) A month of daily backups
3) A new full backup
4) A month of daily backups
5) A new full backup, at the end of which, the data from (1) and (2) is deleted

So, it seems that the "Keep backups" settings has a secret minimum of 1 month (and could hold data for up to 2 months even on the most aggressive setting).

This is a bug, but the alternative would be to make full backups much more frequently which would also be annoying. Perhaps the easiest solution is to remove the "1 week" setting for "keep backups". Is it a problem for you that the data can be kept for so long?

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Vanessa (vsoch) said : 		#2

Hi,

I don't quite understand the distinction between a "full backup" and a "daily backup." I was under the impression that every backup done is a "full" backup, at the rate specified by the scheduling. Are you saying that he default is for the software to do a "full" backup on the first of the month, and then I am supposed to specify if I want a more frequent interval?

I don't quite understand the "at least" setting. You are suggesting that I "make full backups much more frequently" however I already have the most frequent setting specified, "daily." Your second suggestion is to "remove the 1 week setting for keep backups" - however I'm not sure how I m supposed to remove a setting... I have to pick some rate given that I am doing automatic backups!

So with this bug, with the settings on "daily" and "keep at least a week" - you are saying that the best I can do is have two months work of full backups, which is like, 12TB of data? That's a lot of space to pay for on the cloud...

It seems like my only option is really to do a full backup once a week, and manually delete? That kind of sucks :/

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Best Michael Terry (mterry) said : 		#3

Sorry, I was vague.

Regarding your question about "full" vs "daily". So Deja Dup typically makes incremental backups. These backups contain only the difference between the last backup and your current data. So the daily backups in my steps 2 and 4 above are incremental, small backups. Deja Dup will, on its own, occasionally decide to make a full backup. With your current setup, that will be once a month. So once a month, instead of an incremental backup, it will make a full one.

Regarding your question about "at least". I only meant that in the UI, you are choosing a minimum time that you want Deja Dup to keep your data. "Keep backups at least a week". Deja Dup may hold on to the data longer. My suggestion to remove a setting was a note for myself. Because after looking at the code again, I realized that Deja Dup will always hold data for at least a month. So there's little point in letting you the user choose a week. I was just commenting that I should probably remove that option, to reduce confusion like this.

Regarding how much space it will take up in the cloud, you will always have two full backups plus two months of incremental backups, which may take up more space if you have made more changes.

Does that all make sense and does it work in a way that you are happy with?

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Vanessa (vsoch) said : 		#4

Oh, I understand! So each "daily backup" is just the incremental changes, and the full backups are done monthly. I think I was misled into thinking otherwise when I was looking at the "restore" option, and it gave me each day as a possibility. That isn't suggesting that there is a full backup for each day, but rather I would start at some marginal change and then go backwards in time until I hit the full backup.

Storing two full backups and then incremental files along the way is definitely reasonable! I think the interface is good, but it gets confusing when you log into your server / look at your drive to see all the files, and it just seems like a ton. In the future it might be nice to have an interface from within Deja Dup to manage those files, in a less confusing way!

Thank you for your prompt reply, and for answering my question!

Best,

Vanessa

Revision history for this message
Shahar Or (mightyiam) said : 		#5

I never would have guessed that this is the logic.

I was actually looking for and expecting a maximum amount of storage or backups when I found the "at least" setting. Thus I was conused about it.