Hi Koppuru,  Infiniband cables have a max length of 10 meters. so you should place the infiniband switches in a tactical spot so that you can expand to other racks for your cluster growing.
We are planning to purchase A100 backup accelerator for the existing X200 cluster.  In our case we dont have rack space near existing isilon and the backup accelerator must be connected to existing cluster via infiband switches..As far as i know the max cable size of infiband cable is 10 metres..Can't we connect backup accelerator if the distance is more than 10 metres..???
Installing Backup accelerator