UPS - 1 or 2?

Posted on 2006-06-06
Last Modified: 2010-03-19
I now have two servers - one with Active Directory, file and print services.  The second runs mail program and telephones.  We originally had one UPS because we had one server, but our UPS doesn't have enough power for both.  Is it a better practice to add a UPS to the second server, or have one more powerful UPS to handle both.  We already have PowerChute APC Business Edition, so obviously I'd like to keep that.


Question by:texastwostep
    LVL 15

    Expert Comment

    by:Naser Gabaj
    Greetings texastwostep,

    It's a matter of power consumption, you need to calculate how much watt they consume both of them then check the ability of your existing UPS, if it fits why you buy a new one, otherwise you have no choice

    Good Luck!

    LVL 23

    Expert Comment

    by:Erik Bjers
    If you have to buy a new one and the old one is still good, just buy one to handle the new server.  If your old one is rather old or may have problems replace it with one that can handle both servers.

    LVL 4

    Accepted Solution

    Exactly, the UPS power unit is KVA, means 1000 volts/amperes.
    if you are running on single phase its means 1000/1 which is 1000 for each KVA unit,
    if it's triple phase its 1000/1.7~ whcih means 1700~ for every KVA you use.

    you need to check your server's power supplys consumption in watts and by that calculate the required UPS (how much KVA).
    LVL 3

    Expert Comment

    In terms of chosing whether to have multiple UPS vs a single larger UPS I generally strive for simplicity myself.  I prefer to have a single UPS that is network connected so that it can shut down multiple devices and have enough capacity in that UPS to keep the attached hosts up and available.  That being said if you chose to have two UPS then I would spread dual power supplies in both of my servers across both UPS for that additional redundancy in the event that one of the UPS were to have a problem the other should be able to keep both servers up for a period of X minutes.

    For chosing which UPS and possibly battery packs you need for those servers it is a good idea to use one of the selectors like what is on APC's website to chose a UPS with the appropriate specs:

    There is a similar selector on Tripplite's website as well, and I tend to prefer those to the APC units myself b/c several of them are smaller and have the same amount of power as the APC counterparts.

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