From: Phillip Susi <psusi@cfl.rr.com>
To: Yogesh Pahilwan <pahilwan.yogesh@spsoftindia.com>
Cc: linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org
Subject: Re: raw I/O support for Fedora Core 4
Date: Thu, 23 Mar 2006 10:47:34 -0500 [thread overview]
Message-ID: <4422C316.5070305@cfl.rr.com> (raw)
In-Reply-To: <WM57DB3DF98115400697C908A54A80DEE9@spsoftindia.com>
The raw device driver is obsolete because it has been superseded by the
O_DIRECT open flag. If you want to have dd perform unbuffered IO then
pass the iflag=direct option for input, or oflag=direct option for
output, and it will use O_DIRECT to bypass the buffer cache.
This of course assumes that you mean "bypass the buffer cache" when you
say "raw io".
Yogesh Pahilwan wrote:
> Hi All,
>
> I want to do raw I/O on MD RAID and LVM for fedora core 4(kernel 2.6.15.6).
>
> After doing googling I came to know that "raw" command does the raw
> operation by linking
> MD device and LVM volume to the raw device as
>
> # raw /dev/raw/raw1 /dev/md0.
>
> But when I search on this I came to know that there is no raw (/dev/rawctl)
> device support available with 2.6 kernel.
> I have also tried recompile the kernel sources with raw device support it is
> not getting compiled as it is obsolete in 2.6.
> If I want to include raw device support in my kernel what should I will have
> to do, so that I
> Will be able to do raw I/O on MD device and LVM volumes.
>
> Thanks and Regards,
> Yogesh
>
prev parent reply other threads:[~2006-03-23 15:47 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-23 9:24 raw I/O support for Fedora Core 4 Yogesh Pahilwan
2006-03-23 10:07 ` Arjan van de Ven
2006-03-23 15:47 ` Phillip Susi [this message]
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