Re: OT? power reqs of DDR2 chips


Dave Stevens <geek@xxxxxxxxxxxx> writes:
So the setup I envisage is a pair of SATA drives in Raid 0, to get
better access speed, and a single matching SATA outside the RAID
array as the nightly backup device. I plan to use a signalling
UPS. So a worst case occurs when there is a power failure - the UPS
signals the gadget which immediately starts to save all the work in
progress. I think this will exercise the RAM pretty briskly and at
that particular point I want to make sure there is enough power
supply, hence the question.

In that case I don't understand why you are bothering with the dram's
power. Just about everything else in the system is a more significant
drain. And no, your disks, even when streaming aren't going to be
*anywhere* near dram throughput speeds. You do realize disks are
still limited to ~70Mbytes/sec when writing contiguous sectors? Under
real FS conditions you'd be lucky to see half of that. Dram will be
in the low to mid single-digit gigabyte/sec range.

If I were you I'd buy a power meter, measure the actual power and then
get yourself a UPS scaled accordingly. Remember Volt-Amps as defined
by the UPS folks is approx. 0.6 watts. Even at that, they only really
want you to run it at half load. For a measured load of 200watts I'd
get an 800volt-amp unit.

OB Fedora: The APC Back-UPS RS-1500 usb connected UPS is detected just
fine and with apcupsd even shuts the computer down cleanly after a
power failure.

-wolfgang
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Wolfgang S. Rupprecht http://www.wsrcc.com/wolfgang/
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