On 2020-04-01 09:14, Roger Heflin wrote:
To have the issue it helps to have the reading disk be a quite a bit
faster than the receiving disk that way the reading disk can easily
get ahead and fill up the write cache faster than the reading disk can
process it (it backs up into the writecache).
So USB3.0 3.5-7200rpm or an SSD will easily overrun a standard laptop
5900 rpm 2.5" hard disk.
This was not done on a quiet system CPU wise, boinc jobs running. But not much other I/O
going on.
SDD--->USB-Flash
real 16m38.608s
user 0m1.416s
sys 3m37.379s
USB-Flash--->SDD
real 6m37.671s
user 0m0.662s
sys 1m4.984s
I then found an old laptop HDD in a USB 2.0 enclosure. Reading from the SDD should be
much faster
than writing to the HDD.
SDD--->HDD
real 30m53.407s
user 0m0.942s
sys 2m46.756s
HDD--->SDD
real 32m48.615s
user 0m0.896s
sys 1m9.483s
And, for completeness
SDD--->SDD
real 4m58.406s
user 0m0.517s
sys 1m8.402s
No issues at anytime with stability or slowdown in all cases.
--
The key to getting good answers is to ask good questions.