Re: Performance variation in traditional HDDs?

On Wed, Apr 23, 2025 at 10:00 PM Damien Le Moal <[email protected]> wrote:
> So these are drive-managed SMR disks, right ?

Yes. I chose these first because they show the largest performance
difference between two "identical" drives. We do an ATA SECURITY ERASE
to reset their state/LBA mapping - it takes longer than a full drive
write.

Here is another set of identical drives
(https://pcpartpicker.com/product/XtjG3C) that just completed and also
show a significant performance difference. These are CMR drives with
the same model number and firmware.

We did three full drive writes on each drive, using the same proper
horizontal mounting and position.

Looking at the average full drive write speed we saw the following
results in MB/s:

Drive 1: 162.72, 162.73, 162.73
Drive 2: 155.69, 155.70, 155.72

Each individual drive is incredibly consistent in its performance. But
drive 1 is over 4% faster than drive 2.

The difference can be seen in a graph comparing one full write run of each:
https://cdna.pcpartpicker.com/static/forever/images/content/221396115ee6bae8fbd35135fbc6441e.png