From owner-freebsd-fs@FreeBSD.ORG Sun Nov 27 11:27:47 2011 Return-Path: Delivered-To: freebsd-fs@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id B56F8106564A for ; Sun, 27 Nov 2011 11:27:47 +0000 (UTC) (envelope-from lev@FreeBSD.org) Received: from onlyone.friendlyhosting.spb.ru (onlyone.friendlyhosting.spb.ru [IPv6:2a01:4f8:131:60a2::2]) by mx1.freebsd.org (Postfix) with ESMTP id 7BAB48FC0A for ; Sun, 27 Nov 2011 11:27:47 +0000 (UTC) Received: from lion.home.serebryakov.spb.ru (unknown [IPv6:2001:470:923f:1:5974:a369:b987:bc4d]) (Authenticated sender: lev@serebryakov.spb.ru) by onlyone.friendlyhosting.spb.ru (Postfix) with ESMTPA id 4801B4AC1C; Sun, 27 Nov 2011 15:27:46 +0400 (MSK) Date: Sun, 27 Nov 2011 15:27:39 +0400 From: Lev Serebryakov Organization: FreeBSD Project X-Priority: 3 (Normal) Message-ID: <469709203.20111127152739@serebryakov.spb.ru> To: Kirk McKusick In-Reply-To: <201111261712.pAQHCY8G081783@chez.mckusick.com> References: <147455115.20111126115248@serebryakov.spb.ru> <201111261712.pAQHCY8G081783@chez.mckusick.com> MIME-Version: 1.0 Content-Type: text/plain; charset=windows-1251 Content-Transfer-Encoding: quoted-printable Cc: freebsd-fs@FreeBSD.org Subject: Re: Does UFS2 send BIO_FLUSH to GEOM when update metadata (with softupdates)? X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: lev@FreeBSD.org List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 27 Nov 2011 11:27:47 -0000 Hello, Kirk. You wrote 26 =ED=EE=FF=E1=F0=FF 2011 =E3., 21:12:34: > Kostik has it right. The requirement for SU and SU+J is simply > that the underlying I/O subsystem not issue bio_done on a write > until it is on stable store. If the I/O subsystem wants to cache > it for a while (multiple seconds) before writing it to disk that > is fine (SU thinks in terms of 30-second intervals). The only Ok, These "multiple seconds" are good news. > thing that SU requires is that the subsystem NOT lie by issuing > the bio_done before it has committed the data to disk. Perhaps > what we need is a "delay acknowledgement until done' flag to make > this clear. Ok, such flag (and "30 seconds is Ok" statement) will be enough for me (RAID5) to implement robust but high-performance write queuing. But FSYNC flag will be nice and useful too, IMHO. --=20 // Black Lion AKA Lev Serebryakov