What relative size should my backup location be?

Asked by Thomas Chamberlain on 2018-06-14

I read that dejadup is by default configured to keep 2 full backups for corruption protection, as well as incremental ones. Is this correct, and then if so what size drive should I aim to backup to? Is it possible to change these settings within dejadup?

I would guess 3x? For example I want to backup ~1TB of data, so to allow for two full backups and incremental ones, I should be looking at a 3TB drive?

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Déjà Dup Edit question
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Solved by:
Vej
Solved:
2018-06-20
Last query:
2018-06-20
Last reply:
2018-06-18
Best Vej (vej) said : #1

Hello.

You are correct that "dejadup is by default configured to keep 2 full backups for corruption protection, as well as incremental ones".

The drive size is really dependent on the amount of changes. If you backup 1 TB of data, change 1GB of data per day, and do daily updates, you would need at least 1TB * 2 full backups + 29 incremental Backups / per chain * 2 chains * 1 GB / incremental Backup => ~2 TB and 60 GB.

If you change 100 GB per day this means:
 1TB * 2 full backups + 29 incremental Backups / per chain * 2 chains * 100 GB / incremental Backup => ~8 TB.

The above of course ignores compression. If your data is highly compressible (e.g. text) you can divide the necessary sizes by the compression ratio.

I hope this is helpful

Vej

Thank you Vej, that's very helpful indeed.

While I use my laptop regularly, I typically only backup once a week, or after ingesting photos from my camera, so my incremental backups should be relatively small in size.

Unfortunately my data seems not to compress well at all!

As my 1TB drive is not yet full, my 2TB drives should be sufficient for backup, but will probably look to get a larger drive in future.

Thanks again.

Thanks Vej, that solved my question.