+--- In a previous state of mind, "Keith Brown" keith@netapp.com wrote: | | As far as performance goes, the three FCAL loops are peers in the system. | They are "parallel". Each loop is independently connected into the system | via its own FCAL adapter/controller and there is no significant | prioritization of requests/responses on any one loop over another.
Is this true in a clustered failover environment as well or can I tag the failover loops as having a lower priority than the "local" loops? I know, this can lead to starvation (elevator theory) if mis-handled but it could also allow the user to fine-tune their CF setup to their needs.
| Well yes, but distance-from-the-controller is not a significant influencer | of device performance on an FCAL loop. This type of fibre channel
There must be some guidelines though. I would think that you would not want to keep all the loops within some reasonable distance. That is, I would probably want to put my filer in the middle of the rack so all loops are semi-equal as opposed to at the end of the rack (thinking that a filer that takes up 3 racks with 3 fully populated loops).
I am sure the degradation, if any, is not noticeable. Otherwise NetApp would probably stress very precise setups :)
| incorporates some cunning stunts at the MAC layer, borrowed from Token Ring | and FDDI, that do an effective job of spreading the available bandwidth | betwixt all of the connected players, regardless of their physical position | on the loop.
Indeed. fcal is quite spiffy. I still cannot get over the connector being 2 wire pairs in a db-9 connector. I suppose a $5 cable from the local computer store would not really work well in a pinch, eh?
Actually, why the decision to use copper instead of fiber?
Thanks.
Alexei
| | Keith |