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 -- Wolfgang S. Rupprecht http://www.wsrcc.com/wolfgang/ Hints for IPv6 on FC6 http://www.wsrcc.com/wolfgang/fedora/ipv6-tunnel.html
