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Date:      Sat, 5 May 2007 07:30:02 -0700 (PDT)
From:      Arne "Wörner" <arne_woerner@yahoo.com>
To:        Ivan Voras <ivoras@fer.hr>, freebsd-geom@freebsd.org
Subject:   Re: graid5 after-reboot problem
Message-ID:  <398236.18997.qm@web30309.mail.mud.yahoo.com>
In-Reply-To: <f1i3s4$j4n$1@sea.gmane.org>

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--- Ivan Voras <ivoras@fer.hr> wrote:
> Arne Wörner wrote:
> 
> > (that disables the write cache in graid5, which slows down write requests)
> 
> Is the write cache in graid5 aware of what happens on the VFS / UFS
> layers (something like gjournal does)? Otherwise, how can you guarantee
> consistency with write caching at the GEOM layer when there's a power
> outage or some other system interruption?
> 
I cant... :-)
Just like many ATA disks, that just cant turn off their write cache...
(but graid5 can at least turn off its write cache)

But graid5 is aware of BIO_FLUSH... :-))
So somewhen UFS might send a BIO_FLUSH when it is appropriate...
Or gjournal sends the BIO_FLUSH...

-Arne

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