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External HD not recognized while booting (but not always...)


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#1 ambralivio

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Posted 14 November 2013 - 03:40 PM

Hi folks,

Recently I found a very strange behaviour with the system I use for testing, where I use some HD drives connected through a common/usual IDE/SATA to USB adapter.

Lastly, I had the need to make some experimentation by creating a FAT32 partition, in order to install MS-DOS 7.1.

Unfortunately, not having a HD available for that experimentation, I had "to sacrifice" one of my test HDs (previously used as bootable drive), even if it gave me the opportunity to verify and check that it was normally "recognized" by the BIOS and bootable (I usually use the boot manager procedure to choice the drive to boot the system from).

Once I finished with the partition creation and the DOS installation, strangely enough I discovered that the HD was no more recognized and, consequently, no more bootable.

Being almost sure that the simple procedure was correctly followed, I try to boot the external drive "as is" on another system, surprisingly discovering that the drive was effectively "recognized and bootable".

Now, while I am aware about all the problems related with the USB interconnections (USB controllers, ports on the back or on front panel, how/if a USB flash drive can be made  bootable, different behaviour/procedures of different BIOSes, and so forth), what happened to me is really strange, as I was using the same external HD and the same system (BIOS) and the same USB port.
At some point the drive is recognized and bootable, and in others, I'd say normal conditions, it is no more recognized.

The only explanation I could make is about "how the MBR is read/interpreted by certain BIOSes".   

Do you think this is an acceptable educated guess or could be there any other possible main causes which I may not have taken into consideration ?

 

 

:cheers:

ambralivio

 

P.S. - I'd appreciate if someone could post some link on the topic, even though I can assure I have read a lot of threads on the general topic of "bootability" (both within this forum and googling), but none seems to give an answer to the point.



#2 steve6375

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Posted 14 November 2013 - 05:08 PM

USB hard disks have 'spin-up' times and it may not be ready quickly enough.

Also, some USB ports limit power - for USB HDDs you really need to power them externally or by using a USB Y-cable to connect to 2 USB ports to get enough power.



#3 ambralivio

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Posted 14 November 2013 - 05:33 PM

USB hard disks have 'spin-up' times and it may not be ready quickly enough.

Also, some USB ports limit power - for USB HDDs you really need to power them externally or by using a USB Y-cable to connect to 2 USB ports to get enough power.

 

Steve,

 

thank you for all the advices, on which I was aware of, though.

 

Anyway, please read attentively my post.

I stated to have used the same HD drive, the same USB port and the same configuration (meaning the same USB adapter and the same power supply). Even if so, while recognized & bootable before the experiment, the HD was no more recognized & bootable after the DOS installation; at the same time, I wanted to check for the correctness of DOS installation (who vever knows !), by using the same HD (with the same USB adapter and the same configuration) on a different system (with a different BIOS) and all went fine, with the HD resulting well recognized and bootable.



#4 steve6375

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Posted 14 November 2013 - 05:38 PM

So at the moment, you have a USB drive which is not recognised by the BIOS on one particular system - no matter what you do to that system or how you change the BIOS configuration?

So if you look in the BIOS Setup drive list, with the USB drive connected, it does not appear in the list - is that correct?



#5 saddlejib

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Posted 14 November 2013 - 06:02 PM

To clarify..

After changing the format of the hard drive which 'normally' booted on the first system in question it would'nt boot but booted as anticipated on another system.

 

Question:  Was the second system a mirror copy i.e identical computer with regards make, bios and bios version number ????

 

If not this quote  which iv'e taken from your first post which I read several times is probably correct.

 

"The only explanation I could make is about "how the MBR is read/interpreted by certain BIOSes"

 

googling will answer that as more than likely will Steve.



#6 ambralivio

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Posted 14 November 2013 - 06:30 PM

So at the moment, you have a USB drive which is not recognised by the BIOS on one particular system - no matter what you do to that system or how you change the BIOS configuration?

So if you look in the BIOS Setup drive list, with the USB drive connected, it does not appear in the list - is that correct?

Correct !

Besides, whenever a USB drive is recognized in that system, (by using the BIOS boot manager) it appears in the HDs-subgroup.

 

 

To clarify..

After changing the format of the hard drive which 'normally' booted on the first system in question it would'nt boot but booted as anticipated on another system.  Yes

 

Question:  Was the second system a mirror copy i.e identical computer with regards make, bios and bios version number ????

No, it is a different system/MB/BIOS

 

If not this quote  which iv'e taken from your first post which I read several times is probably correct.

 

"The only explanation I could make is about "how the MBR is read/interpreted by certain BIOSes"

 

googling will answer that as more than likely will Steve.

 

????????

 

Please, see my responses in red

 

:cheers:

ambralivio



#7 steve6375

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Posted 14 November 2013 - 06:44 PM

I just wanted to be clear because I have never seen a USB HDD that was not detected by a BIOS (assuming that the BIOS does normally detect USB HDDs) purely due to the way it has been formatted (USB Flash - sure, but not USB HDD).

So you tried adding a BIOS spin-up delay, using ctrl-alt-del during BIOS post to give extra spin-up time, using a Y-Cable + 2 USB ports, using a rear USB-2 socket, using a different USB (short) cable, etc.?

You also tried

1. System switch off  (note OFF, not reboot it)

2. Connect USB drive

3. Switch on and select drive in BBS menu



#8 ambralivio

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Posted 14 November 2013 - 07:13 PM

So you tried adding a BIOS spin-up delay, using ctrl-alt-del during BIOS post to give extra spin-up time, using a Y-Cable + 2 USB ports, using a rear USB-2 socket, using a different USB (short) cable, etc.?

That BIOS does not have any setting related to the spin-up delay, so that I cannot apply this.

Anyway, please re-read my post. I said that with same USB/same system-BIOS/same configuration I obtained 2 different results, according to the different installations/MBRs.

 

The cold reboot, instead of hot, was a nice advice from you and I do not remember now if I made this. I'll try again and let you know.

 

:cheers:

ambralivio



#9 RoyM

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Posted 15 November 2013 - 03:02 AM

Very good gentlemen. 
 
All methods proposed are spot-on for accepted hardware diagnostics.
as for the spin up time, I just power-up USB-HD before PC.
 
P.S. Thanks for sharing your experiences Steve6375.
I just wanted to be clear because I have never seen a USB HDD that was not detected by a BIOS 
(assuming that the BIOS does normally detect USB HDDs) purely due to the way it has been formatted 
(USB Flash - sure, but not USB HDD).
 
Now my Turn to share.
I recently had a WD 500G USB-HD which would "usually" work.
now I have to give it a little help by picking it up, and
twisting the drive back and forth by hand, in order to help 
the platters spin-up. "Time for new USB-HD."
 
I'm now experimenting with a WD 1TB USB HDD, as a multi-boot, multi-partition
USB boot disk all loaded from grub, and I must say that first findings are very good.
 
As things progress with this device, I'll check back and post specifics.
 
Regards, RoyM





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