Swapping DSSI cables

[Russ Carraro]

Customer has an OpwnVMS 7.1 DSSI cluster consisting of 3 AS2100s and 4 HSD30 controllers. Due to the cable connectors he needs to reverse the cable between 2 of the Alphas (there are dual paths so he'll need to reverse both cables). Do all 3 nodes have to be shut down or just the 2 nodes the cables connect or do none of the nodes have to be shut down since there are 2 paths?

[John Gillings]

Russ,

DSSI is NOT hot swap in any way shape or form. You will need to shutdown and power off all systems, disks and controllers on the bus before unplugging anything.

[Ian Miller.]

power off everything before disconecting DSSI cables otherwise Bad Things can happen

[Allan Bowman]

The DSSI busses always need to remain terminated. That being said, there are cases where I have successfully disconnected and then reconnected a DSSI cable with no adverse affect on the system. This would require being assured of no activity on the systems - almost the same as a shutdown.

There are DSSI Y-adapters available that enable you to isolate a single system without taking down the whole bus. These are usually used on HSD controllers, but could also be used on the Alphas.

Allan in Atlanta

[Benjamin Levy]

Original DSSI cables had a retangular connector block, but later ones had two semi-circles cut out of the connector, allowing screwdriver access to the screws holding the jumper block to the device. If those type are installed, the jumper block can be deinstalled while the bus is live.

[Russ Carraro]

Ben, I have BC29S cables that have a straight connector with thumb screws and a right angle connector that has the little holes for a screwdriver. From your description I believe I can replace the cables with the bus live. By "live" do you mean I don't have to shut down any nodes or power, i.e. a hot swap?

[Russ Carraro]

We shut everything down since the customer decided to remove the VAXs and just leave the ALPHAs.