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Date: Sat, 2 Sep 2006 02:43:12 -0700 (PDT)
From: "R. B. Riddick" <arne_woerner@yahoo.com>
To: hardware@ee.ccny.cuny.edu, freebsd-fs@freebsd.org
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Subject: Re: ATA flush cache on sync()
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--- hardware@ee.ccny.cuny.edu wrote:
> When the sync() system call is called on an ATA drive with a UFS 2
> filesystem, is the "FLUSH CACHE" ATA command sent to the drive?
>
As far as I know, when sync() return u cannot even be sure, that the in-kernel
buffers are flushed already...

And the "FLUSH CACHE" ATA command (or BIO_FLUSH since gjournal) is disputed,
since it might break (in FBSD not implemented) concepts like TCQ(?) (tagged
command queuing) or so...

But I think there should be a FLUSH CACHE command from time to time, so that
there cannot be an arbitrary gap...

-Arne


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