Il giorno mar, 24/02/2009 alle 20.49 +0100, Mauro ha scritto:
> 2009/2/23 Mauro <mrsanna1@gmail.com>:
> > 2009/2/23 Federico Di Gregorio <fog@initd.org>:
> >
> >> Io ho fatto così: ho creato due partizioni di / (io uso solo una piccola
> >> boot in ext3, poi la / con sopra tutto il resto esclusa la home a parte)
> >> identiche e nessuna /home. Ho installato. La situazione è:
> >
> > Per non avere sorprese ho smontato la /tmp, formattata ext4, rimontata.
> > All'avvio il kernel mi dice:
> >
> > [ 181.380460] EXT4-fs: barriers enabled
> > [ 181.389561] EXT4 FS on dm-2, internal journal on dm-2:8
> > [ 181.389587] EXT4-fs: delayed allocation enabled
> > [ 181.389612] EXT4-fs: file extents enabled
> > [ 181.390049] EXT4-fs: mballoc enabled
> > [ 181.390076] EXT4-fs: mounted filesystem with ordered data mode
> >
> > ma poi:
> >
> > JBD: barrier-based sync failed on dm-2:8 - disabling barriers
>
> Non avete idea di cosa significa?
> A voi, per chi usa ext4, il kernel non riporta questi messaggi all'avvio?
Dipende dall'hardware che hai. La migliore spigazione l'ho trovate nella
KB della Novell e dice:
By default, the Linux kernel will try to use transaction
barriers. Transaction barriers are an additional mechanism to
help maintain data integrity. In general, modern storage
subsystems may cache writes and may occasionally reorder pending
writes in order to increase write performance. While this is
fine in general, it is not desirable when handling journal data
for journaled filesystems. With journal data, metadata updates,
that is updates to the journal, should be written out to the
storage prior to the regular data they are associated with, to
make true crash recovery possible.
The informational message indicates that the storage driver
and/or the storage device do not support transaction barriers.
Under normal operation, this does not compromise data integrity.
However, barriers do provide a greater degree of performance for
journaling file systems and help ensure data is correctly
written out to the disk.
"JBD" in this message refers to the Journaling Block Device, an
abstraction that was developed to provide the journaling
capabilities of the ext3 filesystem on top of the infrastructure
of the ext2 filesystem on which ext3 is based. JBD is now used
by the OCFS2 filesystem as well.
Il modo per disabilitare il messaggio di errore è disabilitare le
barrier globalmente (barrier=off al boot) oppure disabilitarle al mount
dei device che non le supportano (barrier=0 come opzione di mount).
federico
--
Federico Di Gregorio http://people.initd.org/fog
Debian GNU/Linux Developer fog@debian.org
INIT.D Developer fog@initd.org
I did appreciate the irony that I was whining about encoding issues on
a mailing list that was unable to show those chars, too.
-- Antti S. Lankila to mono-devel-list@
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