Talk:1718: Backups

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I think this makes more sense if only a small portion of all files from the laptop complete the ENTIRE loop. if the total percentage of files which complete the entire loop is 0.0004% , and he backups once a month, that should give him exponential growth slightly smaller than Moore's Law. At 18 months, his total file size would be about 168% of the original. 22:03, 10 August 2016 (UTC)

"Cueball: Wait. My laptop is backing up some folders to this server..." Because of that I agree with you. It's saying "Some" folders are being backed up. The wording heavily implies it's not everything in the computer being backed up just a part.
Even if all the files do make the round trip they might use good deduplication. If all the files round trip but only the changes and a few kilobytes of metadata per file are duplicated then the growth can be exponential. This is only true if none of the backups are compressed or encrypted, though. (talk) (please sign your comments with ~~~~)

Also, the title text my refer to that often when you lose a project and have to start over from scratch, the project become so much better. 01:55, 11 August 2016 (UTC)

This happens. It can really surprise you when the exponential curve is flat enough. We had a case where we kept a log of the backups on a server that was backed up. This went fine for years, until at some point when we ran out of backup space we found that backups of the logs of backups consumed over 99% of our diskspace. 10:04, 11 August 2016 (UTC)

Tee hee! This is why the first thing I exclude from backup is the log directory, or the whole /var tree (with a few selected exceptions, like /var/spool/cron/crontabs - this is a royally misplaced location, it should go under /etc). The logs that need to be kept are sent to a log server, online, by the logger daemon itself. If there's no log server (small systems) at least send the logs to backup place during log rotation. -- 18:59, 11 August 2016 (UTC)
I once managed to backup / to the backup disk at /media/Backup Disk. D'oh. Backupception. -- 12:17, 11 August 2016 (UTC)

I think there should be an explanation, why this setup leads to exponential growth. IMO, it is linear or polynomial of degree 2 at most. Let's assume, the notebook does only contain one file: /A.txt. After one backup-cycle there are two files: /A.txt and /backups/A.txt. After the next one, there are three: /A.txt, /backups/A.txt and /backups/backups/A.txt. Thus the amount of files does only grow in a linear way. Only the path-information is growing faster: The amount of additional directories in the file's path is growing with the square of the amount cycles (it's the sum of all integers from 1 to the cycle-count). Can anybody explain the exponential growth? Epaminaidos (talk) 06:44, 12 August 2016 (UTC)

The number of files grows exponentially, if not a certain amount of data but a percentage of the data is backed up in each cycle. -- 07:31, 12 August 2016 (UTC)
Can you elaborate this? I don't get it. Epaminaidos (talk) 09:50, 12 August 2016 (UTC)
I guess most backup systems keep older backups. First, there's /A.txt. Next, there's /A.txt and /backup/2016-08-12/A.txt. Third, there's /A.txt, /backup/2016-08-12/A.txt, /backup/2016-08-13/A.txt and /backup/2016-08-13/backup/2016-08-12/A.txt. --SlashMe (talk) 09:38, 12 August 2016 (UTC)
Cueball is talking about "syncing folders", not about a backup-system that keeps old versions. Epaminaidos (talk) 09:50, 12 August 2016 (UTC)
 ????? The first two panels say they are creating back-ups. 12:35, 12 August 2016 (UTC)
Actually, there are two backup systems and one sync involved. --SlashMe (talk) 13:17, 12 August 2016 (UTC)