[Info-vax] Processes hang on USB-access

abrsvc dansabrservices at yahoo.com
Thu Feb 17 14:27:16 EST 2022


On Thursday, February 17, 2022 at 2:07:29 PM UTC-5, Dave Froble wrote:
> On 2/17/2022 4:15 AM, Joukj wrote: 
> > Hi all, 
> > 
> > I have an 2 TB USB-disk attached to a DPWS500 running OpenVMS Alpha V8.4-2L1. 
> > After a couple of hours to couple of days the process reading/writing to the 
> > disk seems to hang on the disk access. When some other process tries to access 
> > this disk in this state, it also hangs. A normal reboot of the machine is not 
> > possible anymore since also the dismount of the disk hangs. I have to reset the 
> > machine. 
> > 
> > No errors are logged for the device. 
> > 
> > What could be the problem and how can I avoid processes hanging on access to 
> > this disk? 
> > 
> > I already changed the USB-disk for a brand new one and I changed the machine to 
> > which it is connected. I think I also tried a XP1000. 
> > 
> > 
> > regards 
> > Jouk
> I seem to recall that the USB implementation on older systems from DEC was less 
> than great. You may discover the problem with a system dump and SDA, but, then 
> what? 
> 
> -- 
> David Froble Tel: 724-529-0450 
> Dave Froble Enterprises, Inc. E-Mail: da... at tsoft-inc.com 
> DFE Ultralights, Inc. 
> 170 Grimplin Road 
> Vanderbilt, PA 15486

As with any "problem", knowing what exactly is wrong yields a potential solution.  With a nebulous report of "hangs", there is nothing to go on here.  Is the process waiting for an I/O completion that was missed or never occurred? An examination of the dump would answer this question.  Perhaps there is a code path that results in a deadlock and that is what happened here.  Who knows without additional investigation?



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