Hey Sean,  It has been my experience that you generally are able to add a drive of a higher capacity with caveats.  First the disk needs to be a compatible disk type that is recognized by the OneFS version you are running, some of the newer drives need patches to be recognized and are not compatible with certain node types I would open a support ticket if you are unsure.  Secondly  if you have a compatible disk type and you add a 250GB disk to a node with 160GB disks it wil only see 160GB of the 250GB available, there is no work around for this.  In short you are able to in cerain situations but ultimately getting a like disk type is going to be the best option.  Dan
I have a legacy 1920i cluster running OneFS 6.5 - can I replace a 160GB drive with a 250GB Isilon drive? Thanks  Sean
Isilon 1920i - Can you replacement a disk with one of higher capacity?