Re: [Duplicity-talk] Minimizing risk on incremental

[Mark Grandi]

You can use the par2 wrapper backend that takes a little more space but provides redundancy if one of the chain files gets corrupted somehow (flips a bit...Solar radiation? Bad disk?)

~mark

On Apr 22, 2017 6:15 AM, "Manuel Morales via Duplicity-talk" <address@hidden> wrote:

As written on Wikipedia, about Duplicity:

“Chains consisting of a full backup and a series of incremental backups can be recovered to the point in time that any of the incremental steps were taken. If any of the incremental backups are missing then the incremental backups following it cannot be reconstructed.”

 

Im concerned about those chains, in my particular implementation.

Im using rsync.net as backend, and they automatically create a daily snapshot of whatever we put there.

Each snapshot is a “picture of the file system” as it existed when was taken.

 

If I just do simple rsync to rsync.net, only the changes are transmitted, but the filesystem is a “copy” of the source, not an “incremental backup chain”

Therefore, the rsync.net’s daily snapshot have only the changes, and grows by the size of the data changed every day, letting me recover any snapshot at any time, even if the snapshots in between are lost/deleted.

 

If I use Duplicity, I will be sending incremental every day, and if one of those days is missing or corrupted, all my snapshots are worthless, right?

For example, lets say I have 400 GB of original data, and 2 GB of changes per day.

 

Day 1: Duplicity, first backup, totaling 400 GB (full)

Day 1: rsync.net snapshot (full is recoverable)

Day 2: Duplicity, incremental, totaling 2 GB (incremental)

Day 2: rsync.net snapshot (full is recoverable, incremental might be broken)

Day 3: Duplicity, incremental, totaling 2 GB (incremental)

Day 2: rsync.net snapshot (full is recoverable, incremental might be broken because Day 2 is broken/missing)

Etc

 

If I continue forever, then I might be on day 200 and be able to recovery only full back up from Day1.

What am I missing here?

 

I guess I could do full backup, every week, but that will cause a full 400GB of data every week, so in few weeks I will have a few Terabytes of data on rsync.net.

 

Is there any way to make duplicity just sync the file system, and avoid the incremental part?

The attractive part of duplicity in my case is the encryption, but it seems the “incremental backup” is not ideal for me.

 

Thoughts?

Thanks!

Dotty

 

 

 

 

 

 

 

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