Talk:Raw device
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terms rawdevice and blockdevice are confused.
in linux eg a rawdevice is a special method for accessing blockdevices without using the caching mechanisms of the operating system. database systems tend to implement caching by themselves and prefer raw device access.
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Is a raw device a block device?
I just had the pleasure of setting up raw devices in FC5 and it's a procedure that, to say the least, is poorly documented.
First you have to compile the kernel with raw support. There seem to be two ways, via a kernel module, or by setting CONFIG_RAW_DRIVER=y in .config. That'll get you /dev/rawctl.
Next, you need the raw command, which is missing in FC5. It's supposed to be part of the linux-utils package, but it's not part of the FC5 linux-utils package. You need to compile linux-utils from source to get /sbin/raw or wherever it's supposed to be. I think I put it in /bin.
Next, you need to make the /dev/raw/raw1 ... rawxx devices. And these are character devices.
[root@ raw]# mkdir /dev/raw [root@ raw]# mknod /dev/raw/raw1 c 162 1 [root@ raw]# mknod /dev/raw/raw2 c 162 2 [root@ raw]# ls -l /dev/raw/* crw-r--r-- 1 root root 162, 1 Aug 22 11:31 /dev/raw/raw1 crw-r--r-- 1 root root 162, 2 Aug 22 11:32 /dev/raw/raw2 [root@ raw]# raw /dev/raw/raw1 /dev/sdb /dev/raw/raw1: bound to major 8, minor 16 [root@ raw]#
So is a raw device character or block? 67.111.73.2 16:25, 23 August 2007 (UTC)Rich
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[edit] raw devices are not linux-specific
Raw devices are in no way Linux-specific (quite the contrary). This article should be rewritten in the broader Unix context. jhawkinson (talk) 15:45, 14 January 2008 (UTC)