Backup recommendation
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From: Nix on 22 Dec 2008 17:50 On 21 Dec 2008, Martin Gregorie told this: > On Sun, 21 Dec 2008 15:13:20 +0000, Nix wrote: > >> I'd like to do something similar to this, only keeping it shut down >> except when needed. I haven't paid any attention to hardware for nearly >> a decade so I have no idea if this is possible, but is there a way to >> automatically cut/restore power to something like this under software >> control? (I know I could do it with a wall timer, but that can't be told >> to turn *off* at the right time, so either it'll run for too long or cut >> power in the middle of a backup!) >> > I'd suggest that this is an ideal use for 2.5" laptop drives, since they > are built for a low daily duty cycle and the expectation of a lot of head > take-offs and landings. It would be interesting to know what the spun- > down current consumption of that type of USB drive is too. It should be > under 3 watts spun up if it obeys the USB 2.0 rules. One a day hardly counts as 'a lot'. I now suspect that X10 is what I want: cheap and looks more than capable of this. There aren't likely to be connectivity problems as the machine ordering the powerdown is physically connected to the device powering down and plugged into the same bank of wall sockets, thus guaranteed to be on the same power circuit. > My 3.5" 120 GB WD unit looks bulky enough to contain a desktop drive and > is powered by an external power brick. My backup script explicitly mounts > the drive, does the backup and unmounts it. When the USB drive is mounted > it spins up. If it isn't mounted it times out after a few minutes and > spins down. 'Spins down' doesn't mean it's not still consuming power, possibly quite a lot of it. > Since days can go by between console logins, which of course force an > automount and spin up, the drive is spun up for no more than 90 minutes > per day. Of course the drive's power brick and its chassis electronics > are powered up full time: I haven't thought of a way round that, though I > suppose I could have used a timer socket so its only powered for 2-3 > hours each night. That's where I think X10 will help. -- `We must stand together and fight for our shared cultural heritage as a group of people who cannot stand together to fight for our shared cultural heritage.' --- jspaleta on Balkan balkanization
From: Martin Gregorie on 22 Dec 2008 19:06 On Mon, 22 Dec 2008 22:50:36 +0000, Nix wrote: > One a day hardly counts as 'a lot'. > Agreed. What I meant (and expressed badly) was that that desktop drives are designed for long runs and few stops while laptop drives are designed short runs aqnd lots of stops. I don't have a problem with repeatedly starting and stopping laptop drives, but although popular superstation saya that you shouldn't do that to a desktop drive I've never seen any indication of how harmful stop/ start operation really is to this type of drive. > 'Spins down' doesn't mean it's not still consuming power, possibly quite > a lot of it. > Of course. I've read that laptop drives typically use 2.5-3.5 watts spun up and about 0.5 watts despun, WD Green Caviar drives/ enterprise 2.5" use 5 watts or so and regular desktop drives are in the 10-12 watt range. A conservative guess would therefore be that a 3.5" drive uses 20% of its spun up consumption, so 2.5 watts and add 0.5 watts (guess) for the USB case and 3 watts for its power brick (measured off an old laptop brick). IOW my 3.5" USB thing may well be using 15.5 watts spun up and 6 watts spun down. Measuring its consumption is on my things to do list. > That's where I think X10 will help. > I'll be very interested to see how that pans out and what you end up using to interface it to the PC. Thats a much better plot than using a time switch. -- martin@ | Martin Gregorie gregorie. | Essex, UK org |
From: Nix on 23 Dec 2008 07:38 On 23 Dec 2008, Martin Gregorie outgrape: > I don't have a problem with repeatedly starting and stopping laptop > drives, but although popular superstation saya that you shouldn't do that > to a desktop drive I've never seen any indication of how harmful stop/ > start operation really is to this type of drive. Not that harmful. Most desktop-class drives are only rated for ten hours or so of operation a day, so they're meant for daily shutdown. Server-class drives are rated for more (and cost more). (They're also designed to handle the extra vibration that comes from running near other drives, and so forth.) >> That's where I think X10 will help. >> > I'll be very interested to see how that pans out and what you end up > using to interface it to the PC. Thats a much better plot than using a > time switch. There are lots and lots of X10 interfacing things :) I don't think I need to worry on that score. -- `We must stand together and fight for our shared cultural heritage as a group of people who cannot stand together to fight for our shared cultural heritage.' --- jspaleta on Balkan balkanization
From: Andy Botterill on 23 Dec 2008 09:55 Nix wrote: > > Not that harmful. Most desktop-class drives are only rated for ten hours or > so of operation a day, so they're meant for daily shutdown. > > Server-class drives are rated for more (and cost more). (They're also > designed to handle the extra vibration that comes from running near > other drives, and so forth.) How do I find out what the grade of a hard disk is? When I next do an upgrade I'd like to select something server class like. My Linux system is left on 24 hour a day. Andy
From: Martin Gregorie on 23 Dec 2008 10:32
On Tue, 23 Dec 2008 14:55:45 +0000, Andy Botterill wrote: > Nix wrote: >> >> Not that harmful. Most desktop-class drives are only rated for ten >> hours or so of operation a day, so they're meant for daily shutdown. >> >> Server-class drives are rated for more (and cost more). (They're also >> designed to handle the extra vibration that comes from running near >> other drives, and so forth.) > > How do I find out what the grade of a hard disk is? When I next do an > upgrade I'd like to select something server class like. My Linux system > is left on 24 hour a day. Andy I'm currently running a bog-standard WD Caviar 3.5" drive that's been running 24x7 since September 2005. According to SMARTD reports its temp fluctuates but nothing else changes apart from the usage counter. Possibly more to the point, there are a range of Enterprise 2.5" drives from WD and others that may be the sort of thing that Nix means. Their selling point seems to be high duty cycle and lower power consumption than 3.5", so you can pack a lot more into a rack without cooling problems. For that matter, you'll pay 173 quid for a WD Velociraptor 10,000rpm 300 GB drive compared with 38 quid for a WD Caviar 7,200 rpm 320 GB. Both are SATA-300 3.5" drices, so it would be interesting to know if the extra cost of the Velociraptor means its going to last a lot longer. -- martin@ | Martin Gregorie gregorie. | Essex, UK org | |