service guard disk technology

[singvey]

The current maximum number of nodes supported in an Serviceguard
cluster is 16.
Fast/Wide SCSI disks or disk arrays can be connected to a
maximum of 4 nodes at a time on a shared (multi-initiator) bus.


1.each node has its own shared bus ,why the diskarray connect by fast/wide scsi could only 4 nodes???
2.does the shared bus mean the diskarry scsi interface's scsi chain, so on the chain there are 4 node scsi interface????

thank you !!!!!

[Thayanidhi]

Hi,
It may be restriction in the design of SCSI itself.
The best option would be SAN, where you can assign the vdisks to several nodes.

Do you really need to share a SCSI disk on more than 4 systems?

Regds
TT

[melvyn burnard]

this is a scsi limitation that is based on various issues, not least of which is cable lengths etc.

[Geoff Wild]

That's why it is best to go with SAN attached disks instead - so you don't have to worry about the limitations of SCSI - bacically - if you can afford a 16 node cluster - you can afford SAN attached disks...

Rgds...Geoff