Date: Thu, 21 May 2015 19:49:53 +0100 From: Steven Hartland <killing@multiplay.co.uk> To: freebsd-hackers@freebsd.org Subject: Re: Botched NCQ on SSD - cannot disable? Message-ID: <555E28D1.2070600@multiplay.co.uk> In-Reply-To: <CA%2BK1YHFrxHt5rVU%2BLsH9UN37dr_7or1C7rEB0eHfJisU7sPE0Q@mail.gmail.com> References: <CA%2BK1YHFrxHt5rVU%2BLsH9UN37dr_7or1C7rEB0eHfJisU7sPE0Q@mail.gmail.com>
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We make extensive use of 840 EVO's attached to LSI controllers and never had an issue. What controller are you using? On 21/05/2015 19:42, Neffi wrote: > I was discussing this issue in freenode/#freebsd and I was recommended to > shoot an email to you fellows about it. > > I've got an Samsung 840 EVO SSD (model MZ-7TE250BW), which uses Samsung's > own controller from what I can gather. I had issues of mass data corruption > when used under Linux, and several programs crashing unexpectedly when used > under FreeBSD. I've gone through 2 drives under warranty with the same > issue before customer service suggested to disable drive queuing. > > After some research it seems as though this drive (and several other common > SSDs) report that they support NCQ, but in fact are botched and will have > all sorts of problems with NCQ enabled ranging from poor performance, to > I/O stalls to data corruption. > > Sure enough the logs on Linux spit out something along the lines of: > >> ata1: exception Emask 0x0 SAct 0xf SErr 0x0 action 0x10 frozen >> ata1.00: failed command: READ FPDMA QUEUED > This happens several times when used on Linux, in the few hours leading up > to total filesystem corruption. > > The recommendation in the Linux world is to disable NCQ on these drives, > for which there is an easy boot-time tunable for it. This fixes the issue. > No more data corruption. > > There doesn't seem to be a tunable for this anywhere on FreeBSD. > camcontrol(8) mentions setting the tags used, but only between some > hardcoded limits, with a default of 2 -- not sufficient to disable NCQ on > the drive. It looks like presently the only option is to manually patch the > quirks for this drive in the kernel and recompile before I can even install > the system to the drive. > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org"
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