Total power of redundant PSU

Discussion in 'Power Supplies' started by Iron67, Dec 4, 2017 at 3:13 PM.

  1. Iron67

    Iron67 n00bie

    Messages:
    28
    Joined:
    Oct 4, 2008
    Hi,
    I have this chassis http://www.supermicro.nl/products/chassis/4U/846/SC846XE26-R1K28.cfm?parts=SHOW

    It is equipped with two redundant PSUs and a power distibutor with four slots. Two occupied by the PSUs and two others free for any battery backup power. In the latter it is possible to install additional PSUs.
    The power distrubutor has 6*8pin EPS receptacles, 13*4pin ATA receptacles and 8*8pin EPS headers. At maximum current the PDB should transfer a theoretical power of over 4400W.

    I have some questions to ask you:
    1. Given that the load is distributed on two PSUs, what happens if the total load exceeds that allowed by a single PSU?
    2. Is it possible to configure a redundant N+1 PSU system?
     
    Last edited: Dec 7, 2017 at 6:24 AM
  2. sinisterDei

    sinisterDei Gawd

    Messages:
    513
    Joined:
    Dec 1, 2004
    So, I'm just going to guess here - I don't have one of these chassis and haven't been able to find any literature that describes it in detail.

    1. I haven't been able to find anything that describes the load as 'distributed on two PSUs'. Everywhere I see it discussed, the CPUs are simply described as being 'redundant' which is not the same thing. Most servers with redundant power supplies do not distribute the load, since if a single supply cannot handle the load it violates the descriptor of redundant. I would assume that if the load exceeds the single PSU that you would experience a failure event of some kind.
    2. If the answer to #1 is that the active load is limited to a single PSU, then the inclusion of just two PSUs is N+1. You can use the other bays to add battery or other power supplies to move your way to N+2 or N+3, but I think N itself is fixed at 1.