[Info-vax] hub better than switch?!

[Bob Gezelter]

On Sunday, March 4, 2012 2:14:31 AM UTC-5, Phillip Helbig---undress to reply wrote:
> A while back, I posted a question about a slowly (about 2 per day)
> increasing error count, mostly on PEA0: but occasionally on some disks
> connected to the same machine which shows the errors on PEA0:.  This 
> stopped after my old switch died and I replaced it with a hub (actually 
> this strange 10/100 Mb/s hybrid thingamajig).  I assumed that whatever 
> caused the switch to fail was also responsible for these errors before 
> the failure.
> 
> Since I replaced this "hub" with a brand new 10/100/1000 MB/s proper 
> switch a few days ago, the increasing error count is back.  :-(  It 
> occurs on the one machine in the cluster which has a 100 MB/s ethernet 
> card (the others have 10).  On the switch, this is running at 100 while 
> on the "hub" it ran at 10 (but other things on the hub---an access point 
> and another switch---ran at 100).

Phillip,

Two possibilities occur to me:
- Possible problem with the switch hardware
- Duplex mismatch problems

I have seen strange results when a machine/switch disagree on duplex. The underlying problem (squelched/lost messages or parts thereof) are clear, but the precise times when they occur can be difficult to predict.

I would also be concerned about a loose connection "jittering" due to vibration. Most likely this would involve the modular cable from the VMS system, but I have seen situations where the power connector for the switch was at fault.

Careful trouble shooting will resolve the problem, although it is excruciating with a failure event frequency of 2/day.

- Bob Gezelter, http://www.rlgsc.com