>> Has anyone got any buying tips when looking at portable hard drives?
>>
>> I quite like the IOMEGA 500gb hard drive. Its small, neat and is powered by
>> its usb cable rather than yet another bulky adaptor and socket being used.
which means that a proportion of USB ports will not provide sufficient power to spin it up or keep it spinning.
The USB ports should be fine providing they are not being used to power web cams or any other device. It must also be plugged directly into two USB ports and not into a hub unless the hub has additional power going into it.
Possibly not if they are on the front of the machine and connected to USB pin headers on the motherboard. As you say, the use of two USB ports is advisable
It would depend on the PC and the power supply and if what sort of connector is on the board. If it only had a 20 pin ATX socket and no aditional power and it had been upgraded then it might be an issue.
I admit it can be a problem and I have seen a few machines where the USB ports did not provide enough power but it is fairly rare was computer problems go.
I usualy try and connect these hard drives to the rear USB ports to try and avoid some of these problems.
I've also had a few random power supply issues where amazingly the computer could boot up fine but the USB ports could not power anything simply because the PSU was not supplying enough ampage.
>> I've also had a few random power supply issues where amazingly the computer could boot
>> up fine but the USB ports could not power anything simply because the PSU was
>> not supplying enough ampage.
>>
Had that same problem once, but with the additional symptom of the fans slowing down when the system was working hard.
Got a external hard drive that uses a 2.5" laptop drive, powered from USB and it works with laptops, just the machine mentioned above that couldn't power it.
Some laptops seems particularly poor in their ability to deliver 1A per USB socket.
In answer to the original question I think they're all pretty much of a muchness; like cars, whatever brand you buy there will be those who had had big problems and those that have had none.
I thought each USB port was supposed to deliver 400ma not 1 amp? Its been a long time since I have studied the USB specifications though! Of course now we have USB 3.X the power requirements have probably increased.
Found it, under usb root hub. Never knew it was there but it doesent show how much current a device is drawing through the port. Just tested a small usb hard drive on it.
The listing under the Power tab details the maximum current needed in the case of each device - for instance my mouse requires 70mA according to a check just now.
The external 500Gb 2.5" USB hard drive plugged into my Mac for time machine backups says it needs only 2mA.... which is clearly wrong. And yes I checked the figure whilst doing a backup too.
I bought a Weston Digital 250 GB "Passport drive" that I quite liked (75mm wide, 123mm long, 15mm thick). The light dimmed down when it was safe to disconnect. So when I got a netbook I ordered another one.
By that time it was 320 GB and they had shrunk the case size length by 14mm, (not necessary) but the previous rather nice bright LED had been changed to a pin point of light not quite 1mm diameter on the side of the case. So small that I missed seeing it at all at first, and took it back for not having one.
Had I known they had done this, I would not have bought it. A light showing the state of the disk is important in avoiding getting corrupt data.
>> Had I known they had done this, I would not have bought it. A light showing the state of the
>> disk is important in avoiding getting corrupt data.
But you can tell the operating system to safely unmount/remove the drive before unplugging it. This makes sure any unwritten data is written before you unplug it. The default on Windows is to err on the side of caution and allow drives to be unplugged with little danger of data loss but performance suffers.
"But you can tell the operating system to safely unmount/remove the drive before unplugging it. "
And if you have two external drives in use [one may even be a USB stick] and you just want to unmount one are you always sure you dismounted the correct one?
And if XP is so clever, why do I see it writing to a drive for a few seconds after it has put up a mini-screen telling me it is dismounted?
I like belt and braces when it is my data. I want the confirmation of an LED that flashes when it is writing data and goes into some other mode, like being dimmer, when it is safe to disconnect.
With Windows7 I can disconnect such devices providing there is no light flashing - bit disconcerting when I'm also using a networked XP Pro system as well.