On Fri, 13 Apr 2007, Freels, James D. wrote:
> I discovered today that my tape drive was dirty and did not realize it.
> What happened was the drive sent a scsi error to the kernel/OS and
> somehow the root (/), home (/home), and holding disk area recognized by
> AMANDA was changed from rw access to ro access.  I believe this change
> was made by AMANDA itself.  This happened while AMANDA was backing up.
> 
> I had to reboot the machine to place the ro filesystems back to rw as
> they should be.  I then repeated the attempted backup and the failure
> occurred again exactly the same way (so it was repeatable).  This is
> when I suspected the dirty tape drive.  I cleaned the drive and the
> problem went away.  The backups now work like they should (and have for
> years).
> 
> This is the first time I have seen this.  The drive got dirty due to a
> different person changing the tapes did not realize they should also
> clean the drive occasionally.  I also have new higher-capacity tapes so
> that the same number of tapes will get the driver dirtier quicker.
> 
> Does the switch from rw to ro by AMANDA make sense ??  Is this a
> "feature" ?  This is first I have heard of this.

The Linux kernel (I assume you run Linux?) automatically remounts a file
system ro if it notices a medium error on the underlying disk.

Since there are no actual medium errors on the disk, but problems on the
tape drive (both are on the same SCSI host adapter?), it looks like the SCSI
driver has a bug and incorrectly told the upper layer about an error on
the disk. Is there some more info about the actual error(s) in the kernel logs?

Gr{oetje,eeting}s,

                                                Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert AT linux-m68k 
DOT org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                                            -- Linus Torvalds