burke at mclinux.com
Mon Jul 10 07:43:49 MDT 2000
Dan Yocum wrote:
> OK. I just got done reading through the Kimberlite cluster.html doc and I have a
> couple of questions:
> Since an external RAID solution is outside of my budget at the moment ($15K for
> a 36GB cube from Winchester Systems - dang!) I'm back to JBOD, or more
> specifically, 1 disk with active pass through LVD terminators, since all I want
> to do is prove the software functionality and reliability (seeing is believing -
> I'm an experimentalist).
> I read in section 220.127.116.11 that I only need the terminators on the adapters
> (which makes sense to my little brain), but I look at the diagram, and there are
> terminators at the adapters, as well as on the daisy-chain connectors on the
> JBOD box (which seems redundant). So, which is it?
> Thanks for the info,
Strictly speaking, for maximum reliability you need the active
terminators at BOTH ends of the cable. This enables the cable to be
disconnected from either end while still maintaining propper bus
termination. This allows you to survive an inadvertent cable pull as
well as provide a means to cleanly take one node off the bus for planned
maintenance and upgrades; while allowing the other node to continue to
provide service availability.
Having said that, you can configure a Kimberlite cluster for
testing/development purposes which uses no active terminators at all.
The disadvantage to this approach is that it would be sucesseptible to
cluster outage if any of the SCSI cables get disconnected. So it allows
you to experiment, but I wouldn't put one in a serious deployment
without the terminators.
Tim Burke Tel. 978-446-9166 x232
Mission Critical Linux, Inc burke at mclinux.com
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