[Info-vax] Third node into 2-node cluster

[Hans Bachner]

Phillip Helbig (undress to reply) schrieb am 29.03.2019 um 18:50:
> [snip]
>
> If you have a third node anyway, why not make them equivalent?  Then you
> could lose any one node.  If the third node hosts no disks, then if
> those are shadowed between the other two nodes, if one is down, the
> shadow set has just one member.  If you have controller-based shadowing,
> then the disks are unavailable if the node is.  Unless you have an
> expensive setup where disks can be accessed by all nodes other than via
> MSCP.

Using shadowsets built from local disks on the participating nodes is 
useful for a home cluster or other low priority stuff.

In a production environment you usually have shared storage accessed via 
fibre channel or (rarely these days) shared SCSI, so a multi-member 
shadow set will survive a node leaving the cluster. If a third node is 
considered to replace a quorum disk (probably to reduce cluster 
transition times), I'd assume that shared storage is already in place - 
otherwise the money would be better invested into professional storage.

Just mho,
Hans.