[Info-vax] Clock running very slow on an Alpha

[Peter Weaver]

> First, make sure that BOOT_RESET (IIRC the name) is set to be enabled.
That 
> is, make sure the bus is fully reset when rebooting.
> 
> Time loss problems on these systems tends to be associated with bus errors

> and bus hogs.  The clock is updated by interrupt.  If you get into a 
> situation where there is a high volume of recoverable bus errors, you will

> end up losing interrupts (that is, the latency between a clock interrupt 
> will exceed a clock tick).  Network cards not being initialized fully (see

> above) have been implicated in this error.
>
> Bus "hogs" are PIO devices which do high-speed blind writes to a PCI
device 
> (with no checks to see if the device is ready to accept the write).  What 
> happens in these devices is that it responds with a retry NAK, and keeps 
> responding until ready - and that blocks all other bus activity.  One
device 
> that does this is some graphics - especially the TGA2 based cards.
>
> So - look at the behavior of the system having the problem that is
different 
> than the others.  Errors?  High graphics use?  BOOT_RESET setting?  Etc.

Thanks Fred. The last time this system (and the other systems in the
cluster) booted was when it was moved in the data centre over 650 days ago
so that would have reset the bus.

There are no unusual errors in the error log but I'll double check that the
next time I am there. There are no graphics on any of the boxes.

I'll probably schedule the service people to come in and replace anything
dealing with the clock and set BOOT_RESET at the same time.


Peter Weaver
Certified OpenVMS System Administrator
Certified OpenVMS System Engineer
Winner of the OpenVMS.org Readers' Choice Award for System
Management/Performance
http://www.weaverconsulting.ca
http://www.linkedin.com/in/peterweaver