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Speed assumptions for local backups

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I wanted to confirm the following about local backups (files on one external hard drive to another, both USB 3.0):

  • "Disks and partitions" backups are faster than "Files and folders" (to be clear, I am not backing up sector-by-sector)
    • This speed advantage applies to both the initial and subsequent incremental backups
  • Encryption slows speed
  • Compression slows speed

In the real world, how significant are these factors in terms of overall impact on speed?

Thanks

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meiamnick,

Speed of data manipulation is something that is impacted by a lot of factors so the question of how significant the impact of any particular factor is not something you can pinpoint but rather should be viewed in a general sense all the while knowing that results can vary and change.

You have listed some of the factors that impact backup performance but not all of them.  The list is much larger than you propose here.  In general:

  • Disk and partition backup is faster than file and folders backup due to the fact that backup is performed at the block level for disks and partitions whereas for file and folder backup is performed at the bit level.
  • Encryption itself should not slow the backup process to any meaningful significance.  The cost of encryption is in the power requirement to do the encryption as in CPU cycles.
  • Compression of backup takes place at the time of write to disk.  This is again a CPU intensive operation so the faster the CPU and the more RAM available for the task the faster the compression.

Bottom line is that hardware plays a significant role in performance of backup.  The better the hardware and the higher the amount of available hardware resources the faster the performance.

Thanks so much. Very, very helpful.

For what it's worth, I did an experiment to test speed on Disk/Partition versus File/Folder. In my case, Disk/Partition saved time. To backup all of the contents of an external hard drive (2.6TB of multimedia files):

  • 6.5 hours in Disk/Partition mode
  • 9 hours in File/Folder mode

Thanks again

Yes, I would say that would be expected behavior.  Your experience with multimedia files is indicative of a solid external connection and a good external disk.  Care to share hardware details?