JR4/DV4 design change

Basically we have changed the chassis we use to one providing better cooling, and better OS drive access. In the case of the JR4, we should have better backplane fault isolation, at the cost of a few more wires to deal with internally (e.g. shouldn’t impact customers at all). Costs will be about the same, but serviceability will be easier. All fans are hot swappable, as are power supplies, and disks, including OS drives. Added benefit, you don’t need to open the unit to get at the OS drives. Also added benefit of much larger fans, which move more air. We are measuring a 5-10 degree C drop in the PCIe channel on some of our RAID cards under load. I should also note that we are working on additional cooling for the RAID cards. Trying to avoid liquid cooling for the moment, but at some point, very dense systems will require this or something quite similar.