Re: USB, NetBSD 6.1.5/amd64: freezes when 2 umass connected

[tlaronde%polynum.com@localhost]

On Thu, Jul 02, 2015 at 05:22:27PM +0800, Paul Goyette wrote:
> On Thu, 2 Jul 2015, tlaronde%polynum.com@localhost wrote:
> 
> >Hello,
> >
> >On an NetBSD 6.1.5/amd64, when I connect a second USB connected disk to
> >the machine, NetBSD freezes. Unable to connect remotely; hard reboot
> >required.
> >
> >Questions:
> >
> >1) The machine has two usb ports, with uhub0 and uhub1 first attached
> >resp. to these ones; the uhub2 cascading from uhub0 and uhub3 from
> >uhub1.
> >uhub2 has 6 ports removable;
> >uhub3 has 8 ports removable;
> >Since in /dev/ there are only 8 devices (from usb0 to usb7) could this
> >be the problem? (6 + 8 = 14, even if I have only one USB device---first
> >disk---and the second disk is only the second device; but how are the
> >device nodes assigned to one USB port?)
> >
> >2) The two USB disks are from the same vendor (Western Digital) but not
> >exactly the same model (not the same capacity). Could the USB driver be
> >confused by two similar devices connected to the same(?) USB tree?
> >
> >3) Physically, on the machine, there are USB ports on the rear, and USB
> >ports on the front. Does somebody know if front ports could be
> >"duplicating" rear ports, that is slots on the front be in fact
> >connected to the same ports as the rear ones causing conflict?
> 
> Unlikely.  All of the motherboards i've played with have the rear ports 
> "hard-wired" internally, while the front-panel ports are connected via a 
> "riser cable" to sockets on the motherboard.
> 
> >
> >I'm trying to find what is causing this misbehavior. And a freeze is
> >rather annoying for a node that is mainly supposed to be administrated
> >from remote...
> 
> I've had problems in the past with only a single umass hard-drive being 
> connected.  I use the external WesternDigital hard drive for backups, 
> and as long as only a single process is writing heavily to the drive, 
> all is well.  But if I try to have two different backups running from 
> two different filesystems (whether or not on the same wd<n> physical 
> drive), the external umass/scsi drive hands the entire system and needs 
> a hard-boot.
> 
> I have a gut feeling (without any hard evidence, FWIW!) that there's 
> something not quite MP-safe with umass/scsi....

Well, in my case (the USB disks are used for backup too), the first disk
is not even mounted and is not used when I try to connect the second
one. So no write nor even read operation is attempted on _both_ disks.
And it freezes the whole system (and I have nothing in the messages
after rebooting, indicating whatever...)
-- 
        Thierry Laronde <tlaronde +AT+ polynum +dot+ com>
                     http://www.kergis.com/
                     http://www.arts-po.fr/
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