02-07-2018 10:29 PM
Solved! Go to Solution.
02-07-2018 11:03 PM
both proposal, you and from a client are not the best practices, for a simple reason, you have just TWO Switch each fabric.
the best solution is follow:
ISL both Switch_1 and Switch_2
distribute each one Array Controller 1/ 2 Port A /A ( usually you have 4 Array Port each TWO per Controller ) to Switch_1 and Switch_2
distribute each HBA Port to Switch_1 and Switch_2
the same design for Fabric_B:
02-08-2018 08:12 AM
Thanks a lot Antonio. But in that case, if host and array ports are distributed, will it not be difficult to identify SDD (slow drain devices). In Core-Edge (MAPS) design, it will be easy to identify SDD, isnt it??
02-26-2018 05:08 PM
A core-edge design is only good for one purpose: To make it look good on Visio diagrams.
A SAN design with performance in mind should make sure that locality of reference is applied which basically means to put initiators and targets with these highperformance requirements as close as possible to each other preferably on the same ASIC and in the same port-group.
ISL's should only be used in case physical restrictions apply (like switch placement in a datacenter) or if cross functional storage architectures are in play who's ports are connected somewhere else. (tape/vtl systems is an example.)
Slow-Drain then also has muchless influence on traffic as back-pressure is concentrated in one ASIC and therefore will not flow onto ISL's and other parts of the fabric.
02-27-2018 04:15 AM
Thanks Ervin for the reply.
Its not possible to keep all initiators and targets in the same portgroup/ASIC as there are large number of Initiators while the targets are few in number.
Considering we have 2 * 6520 switches, On 1 switch all initiators(most of them are access gateway NPIV) and on the other switch it is a mix of both initiator and target. The 1st switch is fully populated with very few ports left, whereas the 2nd switch has 30+ ports free. In this scenario (4 * ISL's between two switches) what is the best way to distribute the switch ports or leave it as it is.
Also how to calculate the number of ISL's required between the 2 switches? Any formula to calculate?
02-27-2018 04:33 PM
There is no formula to determine the required number of ISL's.It all depends on workload. The more you can concentrate workload withina switch the less ISL's you need and the better performance you will have plus you leave more port for end-device connectivity.
Look at the provisioning ratio on initiators and targets and try to consolidate this ratio as much as possible onto a switch. Balance it evenly over the amount of switches you have and you're pretty safe.