Subject: Re: external USB cases for ATA drives
To: Florian Stoehr <firstname.lastname@example.org>
From: Denis Lagno <email@example.com>
Date: 01/03/2005 16:02:06
> > I use USB drives sometimes. Flashes work fine.
> > But recently I've got external USB case for hard drive.
> > It turns on the drive only after plugging USB cable in.
> > And 2-3 seconds are needed to spin the drive on.
> > And it often happens that kernel recognizes only umass and
> > scsibus at umass, but not sd itself.
> > So I need to plug it off and on again in hope of finding
> > myself more fortunate.
> > Can it be because of some too restrictive timeouts in the kernel?
> Maybe this is related to the "buffer space" USB bug?
> I wrote a little program some time ago to bypass this. It will allocate,=20
> use and free a given amount of RAM.
I believe it is not direct manifestation of that bug.
I encountered that bug earlier and in that case
kernel used to issue explicit message like "no buffer memory".
(I run DEBUG+DIAGNOSTIC kernels)
That bug seems to be fixed in -current
Also, usually if I just plug drive off and on again,
kernel recognizes sd at scsibus properly.
> At least on -current, I don't think that's it. I just bought an
> external ATA case, too, and it takes about 30 seconds from when I turn
> it on to when I see the console messages showing the attachment.
When kernel recognizes sd properly it takes no more than 3 seconds.
When it is recognizes only umass and scsibus, it does not recognize
sd ever, or at least within 20 minutes.
> What version of NetBSD are you running? If it's 2.0 and you're hitting
> the buffer memory issue, there should be a message; I don't think that
> that message existed in 1.6.x. (I use fvdl's patch, so I don't see the
> problem in any event.)
I run different recent snapshots of -current on two machines,
and both demonstrate the same behaviour with my drive.
Maybe it is just weird behaviour of the particular external case