Date: Wed, 08 Jun 2011 22:21:06 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: Jeremy Chadwick <freebsd@jdc.parodius.com> Cc: freebsd-stable@FreeBSD.org Subject: Re: [SOLVED] Re: labelling root file system (RELENG_8) Message-ID: <4DEFCBA2.10908@FreeBSD.org> In-Reply-To: <20110608165515.GA95345@icarus.home.lan> References: <4DEF7322.8030907@gmx.de> <BANLkTimBYL8e2y86m7GZv5U8hdok3KR%2B=w@mail.gmail.com> <4DEF8103.9030401@gmx.de> <20110608162626.GA94883@icarus.home.lan> <4DEFA5E3.8080806@FreeBSD.org> <20110608165515.GA95345@icarus.home.lan>
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on 08/06/2011 19:55 Jeremy Chadwick said the following: > On Wed, Jun 08, 2011 at 07:40:03PM +0300, Andriy Gapon wrote: >> on 08/06/2011 19:26 Jeremy Chadwick said the following: >>> I have the exact same question except not with regards to labels but >>> toggling TRIM capability on the root filesystem. >>> >>> - Start system >>> - At loader, boot single-user (option 4) >>> - At prompt choose /bin/sh >>> - mount -a >> >> I think that this is a culprit. > > I'll try removing this step. > >>> - tunefs -t enable /dev/ada0s1a --- fails >> >> Shouldn't you have / mounted r/o here? >> BTW, AFAIR, *re*-mounting root read-only won't help; it needs to have never been >> mounted r/w. > > I'm a little confused by this sentence, so my apologise in advance. / > is mounted read-only in single-user by default. Did you mean I should > make it r/w by doing "mount -u -o rw /" ? I may have omitted this step. No. My English is not perfect it seems - my point was that you should never mount your root fs r/w if you want to do tunefs on it. > I will re-verify the exact procedure and exact steps in a moment, and > reply here. > >>> - sysctl kern.geom.debugflags=16 >>> - tunefs -t enable /dev/ada0s1a --- works >>> - tunefs -p /dev/ada0s1a -- shows TRIM enabled >>> - reboot >> >> I think that at this step your superblock on disk gets re-written with its copy in >> memory which has never been updated. But not sure. > > Hmm, I sure hope that isn't the case. I think that this is the case. > That would mean the only time a > person can use tunefs on a root filesystem is when they either do it > manually during the FreeBSD installation (adding "-t" to the list of > newfs flags in the filesystem creation UI), or if they boot off of some > other medium (USB flash drive, CD, PXE, etc.). Or when your root fs is mounted r/o, which is not as bad as what you listed above. -- Andriy Gapon
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