On Thu, Apr 14, 2016 at 9:56 PM, Warren Block <wbl...@wonkity.com> wrote:

> On Thu, 14 Apr 2016, Warner Losh wrote:
> The CAM I/O scheduler has been committed to current. This work is described
>> in https://people.freebsd.org/~imp/bsdcan2015/iosched-v3.pdf though the
>> default scheduler doesn't change the default (old) behavior.
>> One possible issue, however, is that it also enables NCQ Trims on ada
>> SSDs.
>> There are a few rogue drives that claim support for this feature, but
>> actually implement data corrupt instead of queued trims. The list of known
>> rogues is believed to be complete, but some caution is in order.

> Is the list of drives queryable?  Is there an easy way to tell if the
> currently-connected drives are on the list?

/usr/src/sys/cam/ata/ata_da.c has the list.

dmesg will tell you if it detected a bad one since it prints the drive's
But that's no big deal, because the bad one work just fine if you never
a NCQ TRIM. This small group of drives were early adapters of this

Here's the full list of known rogues:

Crucial/Micron M500 (all firmware prior to MU07)
Micron M510 MU01 firmware (newer firmware is good)
Crucial/Micron M550 MU01 firmware (newer firmware is good)
Crucial MX100 MU01 firmware (newer firmware is good)
FCCT M500 all firmware
Samsung 830 all firmware
Samsung 840 all firmware
Samsung 850 all firmware

All of these are at least 18 months old (if not older). There's some
confusing in Linux lists on
the full impact of the Samsung drives (there was a bug in the Linux
implementation (that can't
be present in the FreeBSD implementation) that may have been the root cause
for the Samsung
black listing). Out of an abundance of caution, I've kept them in the list.
Also, it's my belief that
the Crucial/Micron models with MU01 firmware were mostly corrected after
early samples
since most of the channel drives I've helped people debug had MU02
firmware. Also, a quick
google search shows the MU02 firmware for each of these models has been
available for
at least a year.

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