The raw device driver is obsolete because it has been superseded by the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not getting compiled as it is obsolete in 2.6.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
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