69 lines
2.7 KiB
Text
69 lines
2.7 KiB
Text
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Desc: Typical setups for big servers
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File: big-servers.txt
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Date: 14 March 2004
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Auth: Russell Kroll <rkroll@exploits.org>
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By using multiple MONITOR statements in upsmon.conf, you can configure
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an environment where a large machine with redundant power monitors
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multiple separate UPSes. For the examples in this document, I will use
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a HP NetServer LH4 in the stock configuration with 3 of the 4 power
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supplies installed.
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Compared to some systems, the LH4 is unusual because it has common power
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cords for multiple power supplies. One cord feeds two supplies. As a
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result, each UPS drives two of the power supplies, so losing that UPS
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affects both at the same time.
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For our examples, UPS "Alpha" is connected to the cord that drives the
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two power supplies, and ups "Beta" is connected to the other with just a
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single power supply.
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Since the server needs two supplies to stay alive, we can lose "Beta" at
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any time, but losing "Alpha" is a showstopper. We make a note of them
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when configuring upsmon:
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MONITOR ups-alpha@myhost 2 monuser mypass master
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MONITOR ups-beta@myhost 1 monuser mypass master
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MINSUPPLIES 2
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With that configuration, upsmon will only shut down when Alpha reaches
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a critical (on battery + low battery) condition, since Beta by itself
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is not enough to keep the system running. Beta, on the other hand,
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can go up and down as much as it wants and nothing will happen as long
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as the other one keeps working.
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The MINSUPPLIES line tells upsmon that we need at least 2 power supplies
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to be receiving power from a good UPS (on line or on battery, just not
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on battery and low battery).
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Adding redundancy
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=================
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The above example assumed the stock hardware configuration. Let's say
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we have successfully cajoled the boss into providing the money for a
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fourth power supply. Now both power cords run two power supplies, and
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the system is maxed out in terms of redundancy.
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The upsmon.conf must be updated to reflect this:
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MONITOR ups-alpha@myhost 2 monuser mypass master
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MONITOR ups-beta@myhost 2 monuser mypass master
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MINSUPPLIES 2
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Beta is now driving two power supplies, so we upgrade its power value.
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This means that either Alpha *or* Beta can totally shut down and the
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server will be able to keep running.
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As an added bonus, this means you can move a running server from one UPS
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to another without bringing it down since the minimum power will be
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provided at all times.
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Other configurations
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====================
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There are a lot of ways to handle this and they all come down to how many
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power supplies, power cords and independent UPS connections you have. A
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system with a 1:1 cord:supply ratio has more wires stuffed behind it, but
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it's much easier to move things around since any given UPS drives a smaller
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percentage of the overall power.
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