Warner thank you very much. Sent from my iPhone
> On Apr 14, 2016, at 8:17 PM, Warner Losh <i...@bsdimp.com> wrote: > >> On Thu, Apr 14, 2016 at 8:01 PM, Warner Losh <i...@bsdimp.com> wrote: >> >> >> >>> On Thu, Apr 14, 2016 at 7:22 PM, Alfred Perlstein <bri...@mu.org> wrote: >>> >>> >>> >>>> On 4/14/16 3:42 PM, 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. >>>> >>>> Yowch... >>> >>> With data at stake wouldn't a whitelist be better along with a tool for >>> testing it? >>> >>> Example, you have whitelist and blacklist, if the device isn't on either >>> list you output a kernel message and suggest they run a tool to "test" the >>> controller and report back the findings? >> >> >> The only way to test it is to enable it. Run it for a day or six. If your >> data goes away, the drive is a lying sack. There's no tool to detect this >> that I've seen. You run the NCQ trim, it works. You do it again, it works >> again. After a while, if you have a bad drive model, bad things happen that >> are drive model specific. >> >> Did I mention that the black list matches Linux's black list and that only >> a tiny number of drive models lie. I guess I didn't. > > I just sync it back up to the Linux list. This list has been stable for the > past year or so, with only one entry added back in August. All the other > entries came early in Linux's tables. I did add a quirk to allow it on the > Micron/Crucial M500 with MU07 firmware, but only because I've personally > tested that on dozens of drives over the past 6 months under Netflix > streaming video loads after getting the new firmware. > > >> I am thinking of adding a tunable to turn it off though for people that >> are paranoid. > > Actually, since it is already a quirk, you can use the tunable > > kern.cam.ada.X.quirks=0x2 > > to disable NCQ trim. You can change it to 0x3 if you need 4k sectors as > well. So there's no need to change anything to be able to disable it. Given > how long Linux has been in the wild with NCQ enabled (approximately 18 > months), I'm guessing their quirk list is going to be fairly complete. I > have no other systems to cross check this with, but would welcome pointers > if I've overlooked something. I did this bit of code about 15 months ago, > but it wasn't until 6 months ago that I had working SSD firmware to test it > on. > > Warner > _______________________________________________ > email@example.com mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org" > _______________________________________________ firstname.lastname@example.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"