Fencing without fencing?
as far as I understand, I/O fencing consists of two separate concepts, which can both be described with the two different meanings of the word "fencing":
fencing(1): membership arbitration by fighting ("fencing") for the majority of coordination points, via SCSI3 PGR or coordination point servers
fencing(2): data protection by "building a fence" around data disks using SCSI3 PGR
Would it be possible to have data protection (fencing(2)) but without arbitration by fencing(1)?
Reasons for wanting this might be:
- sufficient heartbeat and low-pri interfaces
- management overhead of CP servers (which have to be documented, patched, monitored etc.)
- asymmetric behaviour with 2 coordinator disks in one storage box and only one in the other
As far as I understand, "UseFence = SCSI3" in main.cf enables data protection in the DiskGroup agent but also requires the vxfen module and in order to configure the vxfen module one has to configure a fencing disk group or CP servers. So, as far I can see there is no fencing(2) without fencing(1), but I might have missed a configuration option of vxfen.
So, is it possible to have only data protection?