UPS for more than one server

Ronan Mullally ronan at
Thu Nov 2 03:38:19 CST 2006

Hi Alessandro,

On Tue, 31 Oct 2006, Alessandro FAGLIA wrote:

> Dear list,
> I am going to buy two PE850 server, and I would like to have only one UPS. Boxes will run last Debian stable.
> The first machine is a RAID1 on two 160GB SATA disks with CERC card, while the second will be a RAID5 on three 160GB SCSI disks with PERC card.
> The online self-making server procedure suggests two UPS models:
>  *  APC Smart-UPS 1500i, 950Watt, rack mount (2U)
>  *  APC Smart-UPS 2200i,1600Watt, rack mount (2U)
> >From PE850 technical specifications, I read that the system needs 345W.
> Do you think the first UPS model will be enough for two machines?

The 1500i will work fine.  I've got a Smart-UPS 1000 running 4 machines
(all fairly old, the biggest a dual PIII with a few disks) and with the
UPS claiming a load of 25-30% I get a runtime of 30-35 minutes.

If you play with CPU frequency tuning in the Linux kernel you can probably
extend your runtime by having the servers step-down the CPU when they're

> Moreover, I have the following additional question.
> I would like to manage the automatic shutdown of machines when the UPS is running out of battery. Normally I manage this with a service (e.g. rupsd)
> running on the server and communicating over RS232 with the UPS.
> Will I be able to do that with the UPS I am going to buy (e.g. do they have the ethernet adapter to do this)?
> Can anybody give me some hints in order to implement what I'am asking?
> I read something about SNMP traps, but I cannot find something more specific on the net.
> I will be grateful if somebody can point me some howtos on the Net.

Take a look at apcupsd - (note you'd need to have
your network switch on the UPS as well if you're going to rely on a
network-based solution).

Alternatively, I think APC offer a dual-port serial card for their
Smart-UPS range which will allow you to connect a serial line to two


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