[Info-vax] reboot due to network failure

[Keith Parris]

On 12/13/2011 5:56 AM, Phillip Helbig---undress to reply wrote:
> All the nodes have the same number of votes.  However, the one which
> survived does not have the highest SCSSYSTEMID.

The code which compares SCSSYSTEMID values uses the 6-byte (48-bit) 
DECnet Phase IV-style MAC address format of the SCS System ID, with the 
two low-order bytes being the SCS System ID value, but with the two 
bytes swapped because the Ethernet standard was apparently developed on 
Big-endian hardware, and then the comparison is a character-string 
comparison in Little-endian order, low-order byte first. So while 
deterministic, the decision isn't easy to predict.

If you need a particular node to be the one to survive, give it more votes.

Note that if connectivity loss is partial, in the case of a tie in 
numbers of votes between two possible subsets of the cluster, the number 
of nodes in a subset is the next factor used is selecting the optimal 
subset to survive. If both votes and nodes are equal, then the 
comparison of SCS System ID values (as described above) for the set of 
nodes running the latest version of cluster software is done, with the 
subset having the node with the "highest" value (using that 
character-string comparison) surviving.