Date: Sun, 21 Apr 2013 14:11:04 +0300 From: Alexander Motin <mav@FreeBSD.org> To: Jeremy Chadwick <jdc@koitsu.org> Cc: freebsd-current@freebsd.org, freebsd-stable@freebsd.org, Matthias Andree <mandree@FreeBSD.org> Subject: Re: Any objections/comments on axing out old ATA stack? Message-ID: <5173C948.1010906@FreeBSD.org> In-Reply-To: <20130420212957.GA19158@icarus.home.lan> References: <51536306.5030907@FreeBSD.org> <20130331130409.GO3178@equilibrium.bsdes.net> <C699FE76-B456-49C7-8D3A-DD54F98DAFC1@samsco.org> <515B25D8.7050902@FreeBSD.org> <515BF5AE.4050804@FreeBSD.org> <515CAA04.1050108@FreeBSD.org> <20130403233815.GA65719@icarus.home.lan> <515CC704.90302@FreeBSD.org> <20130404010526.GA66858@icarus.home.lan> <515D3312.3010109@FreeBSD.org> <20130420212957.GA19158@icarus.home.lan>
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On 21.04.2013 00:29, Jeremy Chadwick wrote: > - The ATA commands which lead up to the error also vary. Many are for > write requests, and from some entries I can see that the OS was doing > NCQ writes (WRITE FPDMA QUEUED) and then suddenly decided to do a > classic 28-bit LBA write (WRITE DMA). I'm not sure why an OS would do > this (there's nothing optimal about it) unless there were conditions > occurring where the OS/ATA driver said "this NCQ write isn't working > (timeout, etc.), let me retry with a classic 28-bit LBA write". ATA disk driver in CAM inserts non-queued command every several seconds of continuous load to limit possible command starvation inside the disk. SCSI driver does alike things, but inserts ordered command flag, that does not exist in SATA, instead of different command. -- Alexander Motin
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