From owner-freebsd-questions@FreeBSD.ORG  Thu May 31 12:38:43 2012
Return-Path: <owner-freebsd-questions@FreeBSD.ORG>
Delivered-To: freebsd-questions@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52])
	by hub.freebsd.org (Postfix) with ESMTP id B95E0106566C
	for <freebsd-questions@freebsd.org>;
	Thu, 31 May 2012 12:38:43 +0000 (UTC) (envelope-from nvass@gmx.com)
Received: from mailout-us.gmx.com (mailout-us.gmx.com [74.208.5.67])
	by mx1.freebsd.org (Postfix) with SMTP id 587998FC0A
	for <freebsd-questions@freebsd.org>;
	Thu, 31 May 2012 12:38:43 +0000 (UTC)
Received: (qmail invoked by alias); 31 May 2012 12:38:41 -0000
Received: from g230070075.adsl.alicedsl.de (EHLO [192.168.178.28])
	[92.230.70.75]
	by mail.gmx.com (mp-us004) with SMTP; 31 May 2012 08:38:41 -0400
X-Authenticated: #46156728
X-Provags-ID: V01U2FsdGVkX1+vz5VLJPuv856hpC690tu9Z9gkKx2lSmnxe+9XRI
	dQ6j/l+7s262C6
Message-ID: <4FC76645.3050609@gmx.com>
Date: Thu, 31 May 2012 14:38:29 +0200
From: Nikos Vassiliadis <nvass@gmx.com>
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US;
	rv:1.9.2.17) Gecko/20110414 Thunderbird/3.1.10
MIME-Version: 1.0
To: dmitry@zhigulinet.ru
References: <546749752.20120531141933@zhigulinet.ru>
In-Reply-To: <546749752.20120531141933@zhigulinet.ru>
Content-Type: text/plain; charset=windows-1251; format=flowed
Content-Transfer-Encoding: 7bit
X-Y-GMX-Trusted: 0
Cc: freebsd-questions@freebsd.org
Subject: Re: fsck on a mounted fs as read-only
X-BeenThere: freebsd-questions@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: User questions <freebsd-questions.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-questions>
List-Post: <mailto:freebsd-questions@freebsd.org>
List-Help: <mailto:freebsd-questions-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 31 May 2012 12:38:43 -0000

On 5/31/2012 12:19 PM, dmitry@zhigulinet.ru wrote:
> Good afternoon.
> Could not tell whether you can run fsck on checking mounted file system as read-only, if prior to that with which the parameters
>
>
> ftp # mount
> ...
> / dev/aacd0 on / var / ftp (ufs, NFS exported, local, read-only)

Could you copy & paste the exact lines?
The "/ dev/aacd0 on" & "on / var / ftp" parts make no sense to me.
It should be:
some_dev on some_dir (ufs, NFS exported, local, read-only)

>
> Launched with these parameters and this is what gives
>
> ftp # fsck -yf / dev/aacd0
> ** / Dev/aacd0 (NO WRITE)
> ** Last Mounted on / var / ftp
> ** Phase 1 - Check Blocks and Sizes
>
> As I understand it does not fix the fsck filesystem.
>

fsck filesystem_goes_here
for example "fsck /dev/ada0s1a"
or
fsck mount_point_goes_here
for example "fsck /"

You are probably trying to fsck the wrong device...

Rebooting to single user and fscking the RO mounted / fs works as usual.
Please provide more info.

HTH, Nikos