External hard drive problems

[Ropey Pilot]

I am having problems with my 160Gb USB 2.0 external hard drive.

I have recently (eventually) transferred all my music onto it (thread below - path too deep) but it will only play for a few seconds before the drive dissappears from the PC!

It will only detect it as a hard drive at all if I put it onto my PC's USB 2 port through my non-powered hub (splitter?). If I connect it directly it appears as a 'Phantom Reader' with the icon for a hard drive and with 0GB and a RAW file system.

Someone on the previous thread mentioned the power supply not being 'stiff' enough - but I don't understand why it is detected if I connect it through an extra, unpowered, bit of kit but not if I plug it in directly!

As I don't have any other need for one I don't want to have to buy a powered usb 2 hub to 'give it a go' only to find that it won't make any difference (but I will if it does).


Not a techno nerd myself so would appreciate any info/ suggestions with explanations for the technologically imapired!

Thanks!

[Spinflight]

How big is this enclosed HD? I have a 2.5 inch HD in an enclosure which works fine, though the USB lead does come with a splitter so that I can plug it into 2 USB ports if more power is needed.

I'd guess that you need one of these cables. To the best of my knowledge all USB ports are powered, though evidently not enough to spin up your HD!

[Ropey Pilot]

Ah my first terminology problem! I was referring to an unpowered hub as a 'splitter' not one going the other way.

I could possibly see that using two ports to power the device would provide more 'juice' but that doesn't explain why it will recognise it fom a single port when passed through an unpowered hub and not when connected directly (if anything that would split the power to 4 different devices thus reducing it wouldn't it?):confused:

[Conan the Librarian]

Normally an Ext HD of this size (never seen different!) will be primarily mains powered, the USB controlling just the data side of things.

I think that now is a good time to hook up the external to another PC and begin the process of elimination. If it works there and your music plays, then it is looking very much like the PC itself, wouldn't you agree? Thing here, is to remove any doubt about the HD before delving further into the PC.

Nearly all externals are ready formatted in FAT32 so that any other PC can read and write to them. Very unlikely that you have the better, but NT & XP only NTFS file system in place.

Let us know how it goes,


Conan

[hobie]

On researching USB mini Hubs a few days ago I came across this .......

"A self-powered USB hub can be used to connect digital cameras, card readers, keyboards, mice, MP3 players, memory sticks and many other handheld USB devices. For more robust components such as external drives, printers, scanners or fax machines, an AC-powered USB hub is a better choice. Some of the AC-powered hubs come with an AC-adapter, while others have the capability, but require the separate purchase of an adapter. When shopping for a USB hub, be sure to get one that will best meet your needs."

http://www.wisegeek.com/what-is-a-usb-hub.htm

[Saab Dastard]

RP,

Your experience is strange, as you say the disk is unrecognised when connected directly to the USB port, but sort of works a bit when connected to a non-powered hub.

USB devices are classified either as "Low Power" or "High Power", and use a maximum of 100 or 500 mA respectively.

Since the USB bus can provide a maximum of 500mA divided amongst all devices on the bus, power consumption tends to be a big problem, unless a device (or downstream hub) is self-powered. If you hang a non-powered hub off a USB port, it has to share all the power from its uplink port (which is already sharing the max) to its downlink ports. In theory you can connect 127 devices to a USB Root Hub (but not without external power)!

Note that until the device is recognised by the O/S, it CANNOT receive more than 100mA, so most high power devices require a staged power-up, with a low-power initial configuration stage while the device gets recognised by the system, followed by the full power allocation allowing the device to complete its power-up.

This might explain why your system is able to recognise the device but is unable to supply sufficient power to sustain the reads. Remember, finding the directory listing is just looking at the file allocation table (which may be cached), and may not require full power until you try to stream the files off. But it doesn't explain why it doesn't work with the "raw" port.

Devices that require more than 100mA to configure are going to need either a dual-USB cable (200mA) or some other form of external power supply.

Not all USB implementations are equal, either due to deficiencies in the hardware, BIOS or O/S. There are known problems with power drop (and droop) affecting different chipsets, depending how well (or badly) the circuits have been designed.

Generally, the older the device, the more likely it is not to correctly implement the USB spec. Also, laptops are notorious for suffering power droops and drops - as well as not being able to actually provide full power!

For example, I have a USB external HD that runs fine unpowered off a Compaq laptop, but won't run without external power off an older Toshiba - fortunately, the disk caddy has a useful keyboard/mouse port power adapter.

SD

[Spinflight]

Well since replying to this thread I have now come upon my first two problems with USB devices ever!

Took my own external Hd in to University to nick gigs rather than megs worth and was a little perturbed to find that my external enclosure just say there and made meeping noises. Didn't show up on the list of cool heath robinson devices on explorer etc.

After a quarter of an hour swearing at Bill Gates I plugged the other USB splitty whatsit into the second USB port and bobs your uncle.

Only problem now is that the sprog's new computer's USB ports just sit their laughing at me.

It dosn't rain but it pours.

P.S. I'd really recommend external enclosures.... You can get a 20 gig 2.5" HD for £20 or so and the enclosures are only £5-10. Compare that to these fiddly USB pens which are nowhere near as cool, hold far less and don't even look slightly like James Bond's cigarette case. Even worse they seem to be designed to be slightly too small to hold really dodgy Japanese porn.

[Ropey Pilot]

Thanks for the replies - been away for a few days:

Conan: It is FAT 32 formatted and works fine with my laptop (isn't it normally the other way around?) So it does rather point to my desktop. The other factor may be differing operating systems; my laptop is ME while my destop is XP. The USB 2 ports were a later addition to the machine - but it doesn't work with the original USB 1 ports either (while it does with the USB 1 port on the laptop).


The device is mains powered but 'Saab' has pointed out some power issues which I knew nothing about.

I think the problems are going to remain a mystery so I will try and cure them in cost order - first with a double USB lead and then with a powered hub. Fingers crossed :)

[Conan the Librarian]

ok, so we now can say that the disk per se, is fine. The problem looks to be on the desktop itself, which is useful to know.


It doesn't much like your USB ports does it? If you are looking at a hub or similar, might I suggest a PCI USB 2.0 card? You can get them much cheaper these days than of old. That would provide you with four USB 2.0 ports (Some have firewire on the same card too) that will be as useful as they are cheap. (PM me for sources if it helps)

The reason that I say this, is that I would now suspect your existing USB sockets on the desktop. A new PCI USB 2.0 card will plug into a card slot and be powered from the existing bus and provide plenty of "Oomph"

Just a final thought - the device manager on the desktop has no problems showing with the existing USB layout?


Conan

[Spinflight]

Just another thought, though a highly unlikely one....

What wattage is your PSU? Also you say that the USB 2.0 ports were a recent addition, was this through a card upgrade or a Mobo upgrade?

[Conan the Librarian]

Oh dear.... Just culled this from the Iomega website. I already use one of their external discs, but in the light of this thread, wandered off to do a bit of research for you. It does not mean that this applies to your case, but it is something else to consider.

From the Min PC Specs...


• 300 MHz or higher with certified USB controller (some USB controllers or motherboards may not support all types of USB devices).


Conan

[Conan the Librarian]

0100 Sunday....

I thought I would give you guys a giggle... Two hours ago both of my Ext hard drives fell over badly (160GB Iomega USB 2.0 and 300GB Firewire Maxtor) and I am still here now while I reformat both into NTFS and thank my lucky stars that they were used for backup and not pure archiving.

They went simultaneously and I am working hard to fathom the cause. So far, I am a lucky chappie, 'cos I archive all important stuff to DVD - just in case... Mind you if it all catches fire tonight, the only positive thing I will have left, is that I can at least stay warm.


Yours, by the width of a fag paper,


Conan