Date: Fri, 31 Jul 2009 21:51:21 +0200 From: Roland Smith <rsmith@xs4all.nl> To: PJ <af.gourmet@videotron.ca> Cc: freebsd-questions@freebsd.org Subject: Re: how to boot or access problem file system Message-ID: <20090731195121.GA92292@slackbox.xs4all.nl> In-Reply-To: <4A734215.6080003@videotron.ca> References: <4A71DB2A.4040401@videotron.ca> <20090730190458.GA36265@slackbox.xs4all.nl> <4A71F297.1080903@videotron.ca> <20090730220618.GA40281@slackbox.xs4all.nl> <4A734215.6080003@videotron.ca>
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--W/nzBZO5zC0uMSeA Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Jul 31, 2009 at 03:12:21PM -0400, PJ wrote: > Roland Smith wrote: > > On Thu, Jul 30, 2009 at 03:20:55PM -0400, PJ wrote: > > =20 > >> Roland Smith wrote: > >> =20 > >>> On Thu, Jul 30, 2009 at 01:40:58PM -0400, PJ wrote: > >>> =20 > >>> =20 > >>>> What can be done to access a file system that seems to have the boot > >>>> sector screwed up? > >>>> =20 > > > > I forgot to mention that your boot sector is fine. If it were screwed > > up, you wouldn't get to the boot prompt. > > > > Since the boot code cannot locate your kernel, there are several things > > that could have gone wrong. See below. > > > > <snip> > > =20 > >>>> The /usr files should be ok but how to access? =20 > >>>> =20 > >>> Use fsck_ffs to try and repair the filesystem. > >>> =20 > >>> =20 > >> how can I use it if I can't boot or access the file system? > >> =20 > > > > Use a livefs cd or use the Fixit option in the main menu of sysinstall > > on an install disk. That should get you a shell where you can run > > fsck_ffs on your disk partitions. > > > > If you have booted from CD, list the disk devices with e.g. 'ls > > /dev/ad*'. If you have SCSI drives, use 'da' instead of 'ad'. > > What does that command list? On my machine, I'll get > > something like this: > > > > /dev/ad4 /dev/ad4s1d /dev/ad6 /dev/ad6s1d > > /dev/ad4s1 /dev/ad4s1e /dev/ad6s1 /dev/ad6s1e > > /dev/ad4s1a /dev/ad4s1f /dev/ad6s1a /dev/ad6s1f > > /dev/ad4s1b /dev/ad4s1g /dev/ad6s1b /dev/ad6s1g > > /dev/ad4s1c /dev/ad4s1g.eli /dev/ad6s1c /dev/ad6s1g.eli > > > > If you only see e.g. /dev/ad4 and /dev/ad6, your slice table has been > > overwritten (with fdisk) and your data is lost. If you see /dev/ad4s1 > > but not /dev/ad4s1a-g, the BSD partitions have been removed and your > > data is lost as well. > > > > Since there is only one slice on both ad4 and ad6 (otherwise you'd see > > /dev/ad4s2x) The next step is to examine the disk labels: > > > > bsdlabel /dev/ad4s1 > > # /dev/ad4s1: > > 8 partitions: > > # size offset fstype [fsize bsize bps/cpg] > > a: 1024000 16 4.2BSD 2048 16384 64008=20 > > b: 16777216 1024016 swap =20 > > c: 976768002 0 unused 0 0 # "raw" part, = don't edit > > d: 4194304 17801232 4.2BSD 2048 16384 28528=20 > > e: 104857600 21995536 4.2BSD 2048 16384 28528=20 > > f: 41943040 126853136 4.2BSD 2048 16384 28528=20 > > g: 807971826 168796176 4.2BSD 2048 16384 0 > > > > This tells us that the a, d, e, f and g partition are carrying a BSD > > filesystem, and should be checked with fsck_ffs. > > > > Try these steps and report back what you find. > > > > =20 > >>>> I don't have a problem with irrecoverable files, I would just finally > >>>> understand how things work and what can be done on FBSD. > >>>> =20 > >>> Make regular backups. Especially before big upgrades. > >>> =20 > >>> =20 > >> Maybe the real problem is that the manual is too screwed up (why are > >> there so many problems being brought up on the mailing lists? we can't > >> all be that stupid.) > >> =20 > > > > It is a mailing list for questions. Ipso facto you'll see questions and > > problems on this list. People who are not having problems will not be > > posting very much. :-)=20 > > > > As to the handbook, this is by necessity written by people who are > > knowledgeable on the subject they write on. Unfortunately this sometimes > > lead to really basic steps/assumptions being skipped because they are > > self-evident for the writer. If you gain enough knowledge about a > > subject it becomes really hard to write for people new to the system > > because you've internalized a lot of stuff by then. > > > > If you have specific questions about parts of the handbook, ask. > > > I get the impression that my disks have all been overwritten; it's Don't have impressions. Get the data. Boot from a livefs CD and start a shell as explained in in some of my previous messages. Then use the commands listed above to check your filesystems. *And report back wat you found*. > rather strange that in the instructions to upgrade it says to not change > anything on the Newfs... and that files would not be overwritten... is > that at fact? What instructions are you referring to? Neither the handbook section [http://www.freebsd.org/doc/en/books/handbook/updating-freebsdupdate.html] nor the manual page for freebsd-update mention newfs at all! Nor should the= y. > If that is true, then surely it should be possible to recover files in > the /usr /var and /tmp directories. If the disks have not been > overwritten... I think there was a huge misinformation gap here if this > is not so... For an upgrade, the filesystems are not overwritten. Only a new install creates new filesystems. Please boot from a livefs CD and check the filesystems on the harddisk as explained before and report the results. Roland --=20 R.F.Smith http://www.xs4all.nl/~rsmith/ [plain text _non-HTML_ PGP/GnuPG encrypted/signed email much appreciated] pgp: 1A2B 477F 9970 BA3C 2914 B7CE 1277 EFB0 C321 A725 (KeyID: C321A725) --W/nzBZO5zC0uMSeA Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.12 (FreeBSD) iEYEARECAAYFAkpzSzkACgkQEnfvsMMhpyUdCgCdH8Z5ap+Licslwz4KS5ipQaBB V30AnjHpFU3FZcydOndYTwlKmNXL2gdX =hwbL -----END PGP SIGNATURE----- --W/nzBZO5zC0uMSeA--
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