John B. Smith wrote:
Forgot to mention both drives are SATA

On Sun, 19 Nov 2017 20:25:51 -0500, John B. Smith
wrote:

When backing up one logical drive today I noticed Drive Image was
taking a long time to 'scan' all the drives before it declared itself
ready.
(When I back up my system drive I use Macrium, but when I back up this
particular drive I use old Power Quest Drive Image because it allows
me to set a password).
Eventually I was able to back up the drive. It did seem to take longer
than usual though.
For some reason I later used HD Tune to ck my 2 drives, the 500g
system drive and the 1000g data drive. The 500 reported the usual
170Mb per second. The 1000 reports only 4Mb per second!
Otherwise HD Tune reports the drive healthy and working.
I'm pretty sure it really has slowed down from the above 2
indications. Anybody have any idea what's going on?

You're in PIO mode.

This shouldn't happen.

When there is a measurable error rate, the driver scheme
changes transfer rates, in an attempt to reduce the error
rate. But it doesn't take that many "gear down" attempts
by the driver, until it's in polled transfer mode,
a word is transferred at a time by the CPU. That
destroys transfer rate performance.

When you look in the appropriate dialog, you'll see
that DMA is no longer listed, and it's changed to PIO.
But I can tell just by your transfer rate, what just
happened. "4" is a popular number - that's what I'm using
as evidence.

*******

https://support.microsoft.com/en-ca/...-out-or-crc-er

devmgmt.msc

Expand the IDE ATA/ATAPI Controllers node.

Double-click the controller for which you want
to restore the typical DMA transfer mode.

Click the Driver tab.
Click Uninstall.

When the process completes, restart your computer. When
Windows restarts, the hard disk controller is re-enumerated and
the transfer mode is reset to the default value for each device
that is connected to the controller.

Paul