Thoughts on HDD and SSD speed
I posted a tutorial recently about installing EasyOS to a new 2.5inch SATA3 on my Mele PCG35 Apo mini-PC:
https://easyos.org/install/how-to-install-easyos-on-a-new-ssd.html
...where I reported a write speed of 63MB/sec to the SSD. However,
that is going through some bottlenecks, a file was being copied from my
SanDisk Extreme USB-stick. The SanDisk Extreme, though, is a very fast
drive, so that 63MB/sec is a bit disappointing.
The manufacturer claims "read and write speeds up to 500MB/s and 450MB/s", see here:
https://www.kingston.com/us/ssd/consumer/sa400s37
Well, we can do some simple tests,
eliminating some bottlenecks. Mostly, I am interested in sequential read
and write, of large files. So, creating a 411MB file 'easy.sfs' in
/tmp, then write this to the SSD. /tmp is a tmpfs and the contents of
/tmp will reside in RAM (unless paged-out to a swap partition). Here we
go:
# dd if=/tmp/easy.sfs of=/mnt/sda2/easy.sfs bs=1M conv=fsync status=progress oflag=sync
...we get 153MB/sec. Much better!
Doing the reverse, reading from the SSD, we get 431MB/sec.
Faster, as expected. Note, I had to be very careful with how it is done
in reverse, rebooted first, to make sure everything was flushed from
the virtual memory.
Testing with a USB3 2.5 inch HDD on the Mele:
Write: 56.7MB/sec
Reboot then read: 91.9MB/sec
Over on my HP mid-tower PC, with an internal 5400 RPM SATA HDD, running the same sequential write and read test:
Write to HDD: 19.6MB/sec
Reboot, then read from HDD: 139MB/sec
Tags: tech