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SubjectRe: 2.2.x fails to identify hard disk buffer?
Hi,

It's very likely that Linux does report what the drives returns,
as this field is in the same structure with the other fields
(model, size, etc), and the entire structure is passed to the
host on one command.

However, as far as I remember, the ATA-2 standard defines 0kB as
"unspecified buffer cache size". That is, when the drive reports 0kB
it doesn't want the OS to assume anything about the internal cache
size. It doesn't necessarily mean that there is no cache.

Gadi

On Mon, 1 Nov 1999, Andrea Ferraris wrote:

> Alan Cox wrote:
> >
> > > Fujitsu hard disk, model MHC2040AT. Linux says that the disk has 0KB
> > > cache, Fujitsu says it has a 512KB buffer. What's going on here?
> >
> > Linux is reporting what the drive tells it.
>
> "hda: FUJITSU MPB3032ATU, 3093MB w/0kB Cache, CHS=785/128/63, UDMA"
> my kernel says at boot time.
>
> I have the same problem since years (in 2.0.xx too), but I blindly trust
> in
> Linux (the salesman didn't told me that the disk had some cache and he
> told my
> that it was UDMA), so I thought that I got a bad hard disk drive (it was
> really
> cheap, maybe too much cheap and anyway it works).
>
> But it seems to me that your reply maybe it's a bit too much
> "political":
> it is in a general and ignorant (I speak for me and not for my employer)
> way there are at least 2 manner for a such result; it is
> 1) the drive says buffer size equal 0 and Linux kernel reports it
> 2) the drive says correctly some buffer size different from 0 and Linux
> kernel
> doesn't understand and shows and use 0.
>
> Why are you completely sure that 2) in such cases is false?
>
>
> Andrea Ferraris
>
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