topic Re: difference between raw and block device in Operating System - HP-UX

difference between raw and block device

Scott_20 — Thu, 12 May 2005 15:55:22 GMT

i know it is simple, but I can't find a clear definition of either.
thanks

Re: difference between raw and block device

A. Clay Stephenson — Thu, 12 May 2005 16:01:35 GMT

At the most fundamental level, the difference is the buffer cache. Raw disk devices transfer data to and from the disk directly; block device writes transfer data to the buffer cache and then to the disk at some later time; block device reads do the reverse. This is the fundamental difference between raw and "cooked" (block) i/o. With cooked i/o the concept of logical i/o (ie writes/read to/from the buffer cache) comes into play. With raw i/o only physical i/o applies.

Re: difference between raw and block device

Robert-Jan Goossens — Thu, 12 May 2005 16:01:43 GMT

Hi Scott,

Check this thread.

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=102950

Regards,
Robert-Jan

Re: difference between raw and block device

KCS_1 — Thu, 12 May 2005 20:43:21 GMT

Hi,Scott

Take a look this the following:

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=14654

It might be so helpful for you.

Best wishes
Kim,