You need to add the clause “oflag=sync” on your dd commands. Without it the MB/s numbers are really just measuring how fast you can fill up the RAM cache (for write) or scoop up data from the RAM cache (in the case of read).
Here’s an example from one of my machines with a SATA-III SSD and lots of RAM: rbthomas@nuc8:~$ dd if=/dev/zero of=tempfile bs=1M count=1024 1024+0 records in 1024+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 1.77789 s, 604 MB/s rbthomas@nuc8:~$ dd if=/dev/zero of=tempfile bs=1M count=1024 oflag=sync 1024+0 records in 1024+0 records out 1073741824 bytes (1.1 GB, 1.0 GiB) copied, 4.88158 s, 220 MB/s Hope it helps! Rick > On Jul 21, 2019, at 2:44 PM, Shahryar Afifi <shahryaraf...@yahoo.com> wrote: > > Correct! > I attached a screen shot of read write speed. > The 2 min hibernation time is when there is little or no contents > present. If I have many things opened, it would take more.
