Hi,

On 9/2/21 9:01 PM, Martin K. Petersen wrote:

Hans,

quoted

So it looks like we actually need to disable NCQ for Samsung 860/870
devices when the SATA controller has a vendor-id of PCI_VENDOR_ID_ATI
rather then AMD.

That's another great data point!

I wonder if there actually is a Samsung problem (given that these drives
work fine on other controllers). Or if it is just the queued trim
handling that's broken on 1002:4391 controllers from ATI.

When I originally experimented with queued trim I had systems I could
not get to work. But queued trim worked fine when the same drives were
connected to more modern chipsets (note that this was "did not work at
all" as opposed to "randomly corrupting data").

Do we have any evidence at all of queued trim working with non-Samsung
drives on these controllers? Not sure how many modern SATA drives
actually implement this feature. Maybe the reason we see Samsung drives
in the bug reports is due to a combination of popularity and the fact
that these drives actually implement queued trim support.

The Samsung 860 / 870 series causing issues when queued trim support
is enabled are quite wide-spread, covering many different controller
models from all well known controller vendors (Intel, Asmedia, Marvell
and AMD). So disabling queued-trim support definitely is the right
thing to do (and we should have done so a long time ago, I am to
blame for this not being done sooner).

As for your theory that it is really a problem with the controller
and not the the SSDs, I honestly do not know, but I doubt it,
there are no such reports with any other vendor's SSD or newer
Samsung models, so this seems unlikely.

Regards,

Hans