Heads up

[O. Hartmann]

Am Fri, 15 Apr 2016 08:26:23 -0600
Warner Losh <imp at bsdimp.com> schrieb:

> On Fri, Apr 15, 2016 at 7:51 AM, O. Hartmann <ohartman at zedat.fu-berlin.de>
> wrote:
> 
> > On Thu, 14 Apr 2016 22:19:23 -0600
> > Warner Losh <imp at bsdimp.com> wrote:
> >  
> > > On Thu, Apr 14, 2016 at 9:56 PM, Warren Block <wblock at 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
> > > quirks.
> > > But that's no big deal, because the bad one work just fine if you never
> > > issue
> > > a NCQ TRIM. This small group of drives were early adapters of this
> > > technology
> > >
> > > 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  
> >
> > This is funny,
> >
> > ALL of our Fujitsu Workstations and those I use pprivate do have Micron SSD
> > drives (Fujitsu) and Samsung SSD (830 and 840).
> >  
> 
> Which Micron drives? I'm not familiar with the 'Fujitsu' model for that
> line.

The boxes are Celsius M-7XX series boxes, I checked but forgot, but I think its M600 type
SSDs (sold with workstations Marsch/April 2015).

> The newer ones are fine, the ones listed above with the MU01 firmware
> being bad have MU02 firmware (or newer) available that fixes the problem.
> The M500's firmware exists, but I don't know how available it is. So for
> Micron, solutions to the problem exist.
> 
> The 830 and 840 apparently claim support, but are in the class of drives
> that simply fail to actually work in what may be a reasonable way to detect.
> There's code to do the fallback in there now, but I'm not so sure that it is
> working given some of the reports I've seen. Maybe I need to try to but
> a couple of these drives to see.

I was mistaken, I personally use some 830 and since a couple of weeks 850 (not 840). Both
are marked as you described.

> 
> So - they are the most popular/used drives in a more "professional"
> > environment these days and they get blacklisted :-(
> >  
> 
> At least for the micron drives, you don't want to use NCQ trim on the
> versions listed. It's data corruption roulette. For newer drives, it is
> fine.
> The performance will certainly be no worse than it was before my
> commit.
> 
> Warner
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