When the drive is powered down during a write operation, the sector
which was being written has got an incorrect checksum stored on disk.
So far, so good---but if the sector is read later, the drive returns a
*permanent*, *hard* error, which can only be removed by a low-level
format (IBM provides a tool for it). The drive does not automatically
map out such sectors.
IBM claims this isn't a firmware error, but thinks that this explains
the failures frequently observed with DTLA drivers (which might
reflect reality or not, I don't know, but that's not the point
anyway).
Now my question: Obviously, journaling file systems do not work
correctly on drivers with such behavior. In contrast, a vital data
structure is frequently written to (the journal), so such file systems
*increase* the probability of complete failure (with a bad sector in
the journal, the file system is probably unusable; for non-journaling
file systems, only a part of the data becomes unavailable). Is the
DTLA hard disk behavior regarding aborted writes more common among
contemporary hard drives? Wouldn't this make journaling pretty
pointless?
1. http://www.cooling-solutions.de/dtla-faq (German)
-- Florian Weimer Florian.Weimer@RUS.Uni-Stuttgart.DE University of Stuttgart http://cert.uni-stuttgart.de/ RUS-CERT +49-711-685-5973/fax +49-711-685-5898 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/