1.6TB Data - Sharp Decline in file copying speeds between USB drives

[m654321]

I’ve made an interesting discovery regarding the significant decline in copying/pasting speed, when transferring large amounts of data - the copying speed issue now appears to be solved...

As mentioned in the first post of this thread, I was copying 1.6TB of video files (3000+ files @ average size ~ 500MB) from a 4TB USB Seagate drive (ntfs format) to a 4TB USB Samsung drive (ext4 format). Speeds plummeted from an initial high of around 120-130 MB/s to less than 30 MB/s, resulting in a very significant increase in the time for data transfer to reach completion.

Investigation 1.
First, I wanted to check whether copying from files from a drive with an ntfs format to one with an ext4 format was the culprit.  I had a second 4TB USB Seagate drive (also ntfs formatted). I found no slowdown in speed when copying between USB nfts drives (e.g. speeds remained at 110 to 130 MB/s) throughout the 4 hours it took to copy the 1.6TB.  However, following this observation, I was left unsure whether this was a disk formatting issue or a difference in drive make/model influencing the outcome, i.e. behaviour of Seagate vs. Samsung – so, roll on to Investigation 2 below...

Investigation 2.
I then changed the format of the Samsung drive, from ext4 to nfts. If the copy/paste slowdown I observed initially is due to a difference in drive format between ‘donor’ and ‘receiver’ drive, then there should be no slowdown when copying from Seagate (ntfs) to Samsung (ntfs) – and that’s exactly what I subsequently observed.  Speeds remained high (110 to 130 MB/s) taking around 4 hours to transfer 1.6TB of data, as I observed with the previous Seagate (ntfs) to Seagate (ntfs) copying/pasting.

Conclusion.
The observations above indicate that the speed of copying/pasting a large amount of data, directly from one USB drive to another, is influenced significantly by the drive format.  To maintain high copying/pasting speeds throughout, both USB drives should have the same format, i.e. ntfs in the above case (or ext4 drives, observation of the 6 July 2017).  Conversely, a very significant reduction in data transfer speed will occur if the drives have different formats, i.e. in the above case with a ‘donor’ drive = ntfs, and  ‘recipient’ drive =  ext4.

In view of the above discovery, I’ll therefore now mark this thread as solved 

Regards
Mike