Re: Raw devices (Was:Re: NTFS, FAT32, etc.)

Martin von Loewis (
Thu, 8 May 1997 21:22:54 +0200

> O_SYNC gives synchronous writes but using O_SYNC is not the same
> as having raw devices. Raw device writes skip the buffer cache
> but may or may not be completed before return depending whether
> the kernel uses an intermediate buffer or not.

Now it's getting weird. So you are saying that the kernel might have
an extra internal buffer, which is not counted as buffer cache for
raw devices (this sounds like a terminology issue: any internal buffer
of the kernel for writing could be considered a 'cache').
Anyway, so raw devices do *not* guarantee IO finalization, which means
that in case of a crash, data written to a raw device might get lost?
This does not sound like a very usefull device...