Real World SSD Performance

Posted by JD 01/09/2016 at 15:00

Yes, SSDs tend to be faster than other storage. That is true, but unless you look deeper at the specs, you may end up with poor performance. Let me explain. This is a general knowledge article. Without a huge sample size, anything beyond generalizations don’t mean anything.

Installed an Anker USB3 front-panel on one of the systems here a few months ago. It was purely for convenience since the system has USB3 internal headers and USB3 storage has been working fairly well from the rear ports. Did a few quick checks and everything was just a little slower than I expected. Didn’t have any hard data, just that things were slower than expected. Gave it 3-stars on the review site.

Vendor Nagging

A month later, the vendor – always worried about unhappy customers – emailed trying to help. I put them off, it was holiday time and I had other things to do.

A month after that, they emailed again. Didn’t really have the time, but decided it would be fun, so spent about 2 hrs running tests thru the USB3 front-panel with some different storage devices. Used Bonnie++, a linux disk I/O tool, for the tests. Wouldn’t call it benchmarking, since the tests were highly specific to my needs, not general needs for everyone.

Results

For comparison, internal SATA spinning disks had 100-120Mb/s writes. Mb = Megabits
An encrypted SSD inside an external USB-c to USB3 enclosure, which the manufacturer’s page claimed 180Mbps writes, achieved only 120Mbps writes.
A WD Blue 320G 2.5in laptop drive inside an USB3 enclosure, achieved only 40Mbps writes.
A SanDisk Ultra 32G class10+ SDHC with a USB3 converter achieved only 15Mbps writes.
That same SanDisk with a USB2 converter achieved only 11Mbps writes.

BTW, I looked through the Bonnie++ man pages and they reference K/s for their outputs. They don’t say if that is K-bits or K-bytes. Bad developers. Bad.

What does this say?

  1. It is highly unlikely that most home users will ever come close to the USB3 5Gbps.
  2. USB2 limits of 480Mbps seems to be unattainable too, but most USB2 devices seem stuck well below that.
  3. SSD performance ranges from every slow to 800Mbps and higher, with cost being the main difference in performance. Average cost, current-gen SSDs will get 100-200Mbps writes. Reputable. But we have to know what we are buying.