Jerky video playback

[Ralf Mardorf]

On Wed, 2023-06-14 at 15:01 +0200, Volker Wysk wrote:
> There's another strange thing, which might or might not be related. I have
> two external hard disks, which I use for backups. Both have USB 3. When I
> synchronize the two, I get a data transfer rate which fluctuates between
> about 20 MB/s and 150 MB/s. That's what's displayed by the "rsync" command.
> I expect that this display is smoothed.

Hi,

from hearsay it's what I would expect from shingled magnetic recording
(SMR) drives, see picture: 
https://www.researchgate.net/figure/Real-time-bandwidth-of-SMR-vs-CMR-disks-when-performing-random-writes_fig1_339923370
For visually impaired subscribers a description of the real-time
bandwidth of SMR vs. CMR disks when performing random writes. For CMR
drives it's more or less a flat line, while for SMR drives read:
https://www.musixmatch.com/lyrics/Vengaboys/Up-Down

Probably the data transfer rate of syncing two drives isn't related to
the video issue.

Regards,
Ralf