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From: Linea Recta on 5 Mar 2010 15:32
I have been having trouble with one of my USB hard disks.
It worked for some time, but not reliably.
In practice it randomly dismounted while copying files (and also when not
copying).
After that I had to pull the power plug and reinsert it to make the drive
mount again.

Yesterday this happened again, I got annoyed and, since the drive is still
under a few monthes warranty, I decided to call Medion support.
This guy advised to try it on another USB port.
Initially I was sceptical but nevertheles I gave it a try. Guess what? The
troublesome drive now seems to work like a charm! Problem solved.

But... how is this??? USB ports aren't equal? I changed over cables with the
other USB drive, which still seems to work fine on the former "errorous"
port.

PS both USB2 ports. No hubs.


--
regards,

|\ /|
| \/ |@rk
\../
\/os


From: Paul on 5 Mar 2010 16:56
Linea Recta wrote:
> I have been having trouble with one of my USB hard disks.
> It worked for some time, but not reliably.
> In practice it randomly dismounted while copying files (and also when not
> copying).
> After that I had to pull the power plug and reinsert it to make the drive
> mount again.
>
> Yesterday this happened again, I got annoyed and, since the drive is still
> under a few monthes warranty, I decided to call Medion support.
> This guy advised to try it on another USB port.
> Initially I was sceptical but nevertheles I gave it a try. Guess what? The
> troublesome drive now seems to work like a charm! Problem solved.
>
> But... how is this??? USB ports aren't equal? I changed over cables with the
> other USB drive, which still seems to work fine on the former "errorous"
> port.
>
> PS both USB2 ports. No hubs.
>
>

Is this a bus powered 2.5" USB hard drive ?

The USB port has a limit of 500mA.

The power is policed in different ways.

On my Asus desktop motherboards, a single Polyfuse is used to power
two ports in a stack. The fuse is rated at slightly more than 1 amp.
If only one USB connector in the stack is being used, the peripheral
could draw current close to that level.

On some laptops, and also some hub devices, they use a silicon solution
for USB power monitoring. You can get an 8 pin chip that will measure the
power and cut off the flow at just over 500mA (the port limit).

The two implementations differ in the limit they have in hardware.
The laptop is less likely to be forgiving, on overcurrent.

If you look at the specifications of raw 2.5" USB drives now, some
give the appearance of needing less than 500mA. In many of those
cases, the "spinup current" is not specified. On some of the older
drives, it is 5V @ 1000mA. If a newer drive doesn't state that limit,
then we don't know whether it is better than the old drives, or the
same.

Some 2.5" USB enclosures, include cabling solutions to enhance current
flow. The first kind they made, has two USB connectors for the host
end, and one USB connector on the peripheral end. The intention of that
cable, is to add the current flow from two connectors. Of the two
connectors on the host end, only one connector has the D+ and D-
data pins connected.

A second cabling solution, provides two USB cables. One is an ordinary
shielded USB2 cable. The second, has a host connector on one end, and
a barrel power connector which plugs into a 5VDC hole on the drive
enclosure. This is doing something similar to the "two headed" cable,
only providing two separate cables to do it. The two separate cables
might encourage a larger separation between the two ports used
on the computer.

There are some enclosure purchases, that include an actual 5VDC adapter
in the box. These leave nothing to the imagination, and will simply work.
But if an enclosure maker is going to shave the parts list to the bare
minimum, there is no reason to be doing it right. It's more fun if
the end-users go around, with their hard drive working half the time.

Paul
From: Linea Recta on 6 Mar 2010 08:38
I have been trying to reply to your message, until now without success.
It is possible that multiple attempts may appear here.



--
regards,

|\ /|
| \/ |@rk
\../
\/os


From: Paul on 9 Mar 2010 10:35
Linea Recta wrote:
> "Paul" <nospam(a)needed.com> schreef in bericht
> news:hmu2p3$p6s$1(a)speranza.aioe.org...
>> Linea Recta wrote:

>>>
>>> Below I'll paste detailed information report:
>>> -----------------------------------------------------
>>>
>>> Hard Disk Summary
>>> Hard Disk Number,3
>>> Interface,JMicron USB/ATA
>>> Vendor Information,"VID: 152D, PID: 2336"
>>> Hard Disk Model ID,ST3500820AS
>>> Firmware Revision,SD45
>>> Hard Disk Serial Number,9QM2K3L7
>>> Total Size,476937 MB
>>> Power State,Active
>>>

>> Seagate did have an issue with firmware on their drives a while back.
>> There was a short stink about it. Seagate doesn't typically offer firmware
>> updates directly on the web site, but vets them via their tech support.
>>
>> I see your raw drive model number ST3500820AS here, but perhaps your
>> firmware has already been updated (i.e. not an affected version).
>> Your firmware version of SD45 isn't in the table.
>
>
> I see... but I'm not sure about the implimentation, i.e. how can I know for
> sure which firmware is the latest? These codes don't ring a bell and I don't
> see any release dates...
> Furthermore I tried their Drive Detect software: it seems to detect all my
> maxtor(!) drives, even the external one, but it does NOT detect the
> Medion/Seagate in question!

If the software doesn't work, perhaps you can take the info you pasted
in your "detailed information report" above, and contact Seagate tech
support. It is possible their Drive Detect software is designed for
directly connected drives, rather than USB ones. Similarly, if
they have a firmware updater, a question would be whether that runs
on a directly connected port, or can work through USB. My experience
(with flashing optical drives), is they should be directly connected.

>
>
> I have 2 USB1 connections and 4 USB2 connections, all of them located at the
> rear end of the comuter (and btw diastrously out of reach...)
>
>
> The Medion enclosure has no fan, but it does have air slots. Temperature is
> never becomming exeedingly high on the outside.
>
>
> For my external Maxtror I have a utility to set the spindown time or to
> disable it.
> For the Medion I have no such thing, nor could find any on the internet.
> Later on I discovered that it spins down anyway after some time, by a built
> in parameter I suppose.
>
> Thanks for all your input,
>

For the USB ports which are out of reach, you could always plug a
cable into them, and leave the cable end located in a convenient location.

That is one of the reasons, that I keep my computers on the desktop. I can reach
all sides of the computers. My computer table is 4' x 4', so there is room
for plenty of junk.

If you want to browse through the ATA/ATAPI spec, there is an example here
of one. Section 7.18.3 has a "Table 40" with Standby Timer value settings.
In the case of your drive housed in a USB enclosure, it could be the
enclosure chip that sets the value. It isn't clear whether that value is
preserved across power cycles or not, by the drive, or whether it has
to be programmed at each power up. (And at 500 pages in length for the
spec, if would likely take a few minutes to figure that out.)

http://www.t13.org/Documents/UploadedDocuments/docs2008/D1699r6a-ATA8-ACS.pdf

Paul
From: shawn on 9 Mar 2010 15:15
I had problems with using front USB ports as opposed to the rear ones in my
computer. Seems the front ones were low power or something. One manufacturer
makes a keyboard I used to own, which has two USB ports on them, but they're
worthless since they were low powered. It wasn't useful in that my devices
needed more.

"Linea Recta" <mccm.vos(a)abc.invalid> wrote in message
news:e9avCMKvKHA.3896(a)TK2MSFTNGP02.phx.gbl...
>I have been having trouble with one of my USB hard disks.
> It worked for some time, but not reliably.
> In practice it randomly dismounted while copying files (and also when not
> copying).
> After that I had to pull the power plug and reinsert it to make the drive
> mount again.
>
> Yesterday this happened again, I got annoyed and, since the drive is still
> under a few monthes warranty, I decided to call Medion support.
> This guy advised to try it on another USB port.
> Initially I was sceptical but nevertheles I gave it a try. Guess what? The
> troublesome drive now seems to work like a charm! Problem solved.
>
> But... how is this??? USB ports aren't equal? I changed over cables with
> the other USB drive, which still seems to work fine on the former
> "errorous" port.
>
> PS both USB2 ports. No hubs.
>
>
> --
> regards,
>
> |\ /|
> | \/ |@rk
> \../
> \/os
>
>


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