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Date:      Wed, 19 Feb 1997 22:51:11 -0700
From:      Warner Losh <imp@village.org>
To:        asami@vader.cs.berkeley.edu (Satoshi Asami)
Cc:        joerg_wunsch@uriah.heep.sax.de, james@wgold.demon.co.uk, hackers@freebsd.org, dufault@hda.com
Subject:   Re: [Fwd: Failed mail: unknown user] 
Message-ID:  <E0vxRPT-0006tK-00@rover.village.org>
In-Reply-To: Your message of "Wed, 19 Feb 1997 16:52:38 PST." <199702200052.QAA00662@silvia.HIP.Berkeley.EDU> 
References:  <199702200052.QAA00662@silvia.HIP.Berkeley.EDU>  

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In message <199702200052.QAA00662@silvia.HIP.Berkeley.EDU> Satoshi Asami writes:
: Really?  I think drives have their own cache, and if they have write
: buffering turned on, they will happily return "write complete" when
: they are only holding data in the buffer.

Yes.  Most modern drives have this feature.

: I know Seagate ST15150WC (old Barracuda 4) had the write buffer
: disabled, while Quantum 34300WC (Atlas 4) had it enabled.  If you
: really want to make sure you write through to the platter, either get
: one of those that don't have it turned on or turn it off by youself
: (I heard it's in one of the SCSI mode pages).

Don't know if you can turn it off, but a friend at Conner once told me
that they use the drive's momentum to power the rest of the drive long
enough to flush out the cache to media, and then they engage the
brakes.

Warner



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