Date: Fri, 15 Oct 2010 17:19:22 -0400 From: Scott Charron <shewless@unleashed-web.org> To: freebsd-fs@freebsd.org, shewless@unleashed-web.org Subject: Re: consistent file system inconsistencies (tried replacing drive) Message-ID: <AANLkTi=jcf7vAAc6yPurpjrLP9tVxVtOkdrV7ZSdc7HM@mail.gmail.com> In-Reply-To: <201010151932.o9FJWXb3066388@lurza.secnetix.de> References: <AANLkTi=RMKLpVzv48Pu1Wk=afCL0NU-v-D0p2_A5JdNe@mail.gmail.com> <201010151932.o9FJWXb3066388@lurza.secnetix.de>
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> This problem was fixed some time ago, i.e. now the freeing > of disk space is not delayed if there is no free space left > on the file system. =A0But the default of not enabling soft- > updates on the root partition was kept. =A0Normally it's > not very important because there aren't many files written > to on the root file system during normal operation. =A0Unless > you have /tmp or similar things included on your root file > system. =A0BTW, you also might want to disable atime-updates > on the root-file system (mount option "noatime"), unless > you have a reason why you need them. I will disable atime-updates > > =A0> Also I was under the impression soft-updates would actually require > =A0> a little more disk access time and thus make the problem slightly > =A0> worse. > > No, soft-updates doesn't require more disk access time in > general. =A0It caches and re-orders meta data updates, so it > can even save disk access time. =A0But the important thing > is that soft-updates re-orders the meta data updates in a > way that guarantees that it is in a consistent state at > any time (provided that the disk's firware cooperates > correctly). =A0This means that there won't be _unexpected_ > inconsistencies after a crash, and fsck will be able to > run without user-intervention. =A0(NB: =A0If you want to avoid > fsck completely, you will have to use journalling, or go > to a ZFS-only system without any UFS file systems.) > Maybe I should just go to ZFS... it's fully supported now even for root right? Will that be more robust against power outages?? > If you still get unexpected inconsistencies even though > you use soft-updates everywhere, then something else must > be wrong. =A0Maybe your hard disk doesn't play along nicely. > The usual recommendation is to disable the write-cache > on hard disks. =A0This will make your system slower, though. Remember I'm using a USB stick here :) > If you see filesystem problems on your non-root filesystem as well, e.g. > ones with SU (soft-updates) applied, I would recommend setting > background_fsck=3D"no" in your /etc/rc.conf. There are some old threads > documenting how background filesystem checks don't always fix all > problems before the system starts actually using the filesystem. There > were reports of people finding that manual fsck would detect issues that > background fsck wouldn't fix. YMMV. Is this recommended? Should I schedule regular manual fscks? Thank you.
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