fsck unable to read disk sectors

[Bernd Walter]

On Tue, May 11, 2010 at 10:15:13PM +0200, Alexander Best wrote:
> i've posted a log here which is pretty self explanatory:
> 
> http://pastebin.com/tn3NiDDW
> 
> On Tue, May 11, 2010 at 10:13 PM, Alexander Best
> <alexbestms at uni-muenster.de> wrote:
> > the problem is getting more awkward.
> >
> > if i do `fsck /dev/label/rootfs` fsck complains that it cannot read a
> > specific sector of my hdd as i mentioned before. if i run fsck on the
> > device node directly using `fsck /dev/ada0p3` however, fsck succeeds.

So this is not hardware it is bad partitioning.

> > what i did was to boot into single user mode with / being mounted read
> > only. for some reason however fsck will check /dev/label/rootfs in
> > write mode, but if i want fsck to check ada0p3 it will only do so in
> > read mode.
> >
> > this looks like something is really broken. right now the only way to
> > get the clean flag set on my hdd is to boot from a livefs cd and then
> > run `fsck /dev/ada0p3` (again: `fsck /dev/label/rootfs` will NOT
> > succeed).

One of the typical problems users have is that they forget that
adding a label takes one sector, so the labeled device is smaller.
This is no problem if you create the filesystem on the labeled
drive, but often enough people add the label after creating the
filesystem.
Everything seems to work fine until the FS decides to use that special
sector.
I wouldn't add a label for ufs anyway, since UFS has labeling itself,
which is also handled by glabel module and doesn't require extra space.
Just setup the ufs label with tunefs -L and use the resulting /dev/ufs/...
device.
You only need extra label for swap, but this is not problem, since
it has no persistent ondisk structures.

> > this is the output of `glabel status` btw:
> >
> >                                     Name  Status  Components
> >                               label/boot     N/A  ada0p1
> > gptid/e52df583-e446-11de-bb92-000fb58207c8     N/A  ada0p1
> >                               label/swap     N/A  ada0p2
> >                             label/rootfs     N/A  ada0p3
> >
> > cheers.
> >
> > On Tue, Mar 30, 2010 at 2:08 AM, Paul B Mahol <onemda at gmail.com> wrote:
> >> On 3/29/10, Alexander Best <alexbestms at wwu.de> wrote:
> >>> hi there,
> >>>
> >>> when doing fsck on my / fs i get this error:
> >>>
> >>> "Cannot Read BLK. 471617640" and "The Following Disk Sectors could not be
> >>> read: 471617643". after this message the partition gets marked dirty.
> >>>
> >>> i performed the following steps to verify the problem:
> >>>
> >>> 1) dd if=/dev/ada0 of=/dev/null bs=1m
> >>> 2) fsck / under freebsd 7
> >>> 3) mount -u -o snapshot /.snap/snapshot1 / && fsck_ffs /.snap/snapshot1
> >>>
> >>> all three steps showed no problem with that harddrive whatsoever. also
> >>> smartd
> >>> doesn't complain about anything.
> >>>
> >>> i'm running HEAD (r205860) on amd64.
> >>>
> >>> this is the output of `dmesg -a|grep ada0`:
> >>>
> >>> ada0 at ahcich2 bus 0 scbus3 target 0 lun 0
> >>> ada0: <SAMSUNG SP2504C VT100-50> ATA-7 SATA 2.x device
> >>> ada0: 300.000MB/s transfers (SATA 2.x, UDMA6, PIO 8192bytes)
> >>> ada0: Command Queueing enabled
> >>> ada0: 238474MB (488395055 512 byte sectors: 16H 63S/T 16383C)
> >>
> >> Last time I tried ahci on dead disk it did not complained at all
> >> (usually I get dead LBA listed on console).

-- 
B.Walter <bernd at bwct.de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.