🚀 go-pugleaf

cdewick@orb.apana.org.au (Craig Dewick) writes:

>I'd never really given much time to think about the benefits of parity
>checking of RAM, but this afternoon I have come home to find that my 3/80
>had self-rebooted at 17:19 when the kernel detected a parity error. I'll
>let the log file speak for itself.... 

[...]

>Anyway, I'm a little confused as to how this error was actually detected,
>and since it hasn't occured again would I be right to assume that it might
>have been a random thing and not a *real* RAM problem? I was under the
>impression that RAM integrity checking was only ever done as part of the
>power-on self test. 

The whole point of parity ram is that you detect errors while the machine
is running. Dynamic ram, being essentially a capacitor, can be discharged
by radiation - it's actually not that uncommon for single bit errors to
occur.

The NCR machines that I used to use had error correcting ram - they would
log a correction about once every six months (these machines generally had
uptimes in the order of years).

--
Andrew McNamara
System Engineer
connect.com.au Pty Ltd