Date: Thu, 31 May 2012 07:16:09 -0600 (MDT) From: Warren Block <wblock@wonkity.com> To: Polytropon <freebsd@edvax.de> Cc: dmitry@zhigulinet.ru, freebsd-questions@freebsd.org Subject: Re: fsck on a mounted fs as read-only Message-ID: <alpine.BSF.2.00.1205310711590.81499@wonkity.com> In-Reply-To: <20120531134636.e070cef2.freebsd@edvax.de> References: <546749752.20120531141933@zhigulinet.ru> <20120531134636.e070cef2.freebsd@edvax.de>
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On Thu, 31 May 2012, Polytropon wrote: > On Thu, 31 May 2012 14:19:33 +0400, 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) >> >> 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. > > Correct. For file system modifications the file system may not > be mounted because "lower level operations" maybe will take > place. In your current setting, only checks will be performed, > but _if_ something needs to be modified, it will not happen. > The reason: It _might_ affect the file system to change, even > if it's "just" in read-only state. > > Solution: Unmount the file system and re-run fsck. fsck(8) can work on filesystems mounted read only. If, say, graphics/cairo causes X to crash the machine, rebooting into single-user mode and running # fsck -y -t ufs will clean up the read-only mounted / also. Agreed that this should be avoided if possible, but sometimes it is necessary.
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