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boucbaz
04-29-2011, 09:51 PM
Must be easy for you guys, Dell laptop,Win 7..When I plug an USB HD it automatically goes to drive ''M'' as drive letter. If I plugged another one on another USB port, it desn't see the second one. Take off the first one and after a while, the second one comes up as ''M''. needless to say I can't use both. Even if I change the drive letter to ''N'' through Admin tools, they both go for ''N'' with one of them not working. Every SMD card and others take on the right drive letter ''E'', ''F''..etc. There must be a configuration somewhere that limits the external HD to one drive only. One more thing, I could map a share drive and it goes to ''Z'' or whatever letter I assigned. Thks and hope I made it clear for you.
P.S. I forgot to mention, those drives on another PC are OK with assigning the next available drive for each of them....

classicsoftware
05-02-2011, 11:43 PM
Put the drive and go to disk management and change the drive letter to S for storage or I for information. Once you do that, it will always go to that letter. Assign the other dive a different letter and you should be good to go.

Paul Komski
05-03-2011, 03:25 AM
If I plugged another one on another USB port, it desn't see the second one.
This shouldn't really happen and should not be due to any conflict with drive letter assignments. It sounds possible that the port or hub is bad or underpowered. It is still good advice to assign drive letters way up the alphabet, since as indicated, you can then link a specific drive to a specific letter (or even to a named empty folder under NTFS file systems).

What type of USB externals (2.5 or 3.5) and is there any way to use any accessory power cable?
How many ports on the laptop?

If it is power-related there would possibilities of using an external powered hub or a PCMCIA card with USB ports.

boucbaz
05-03-2011, 07:17 PM
From Windows 7., 4USB port, Dell I7, full equipped....I think I wasn't very clear, even if I change the drive letter to let's say ''S'' and reboot, that drive would stay as ''S'' and if a plug the other one, it search for a while and stop not assigning a letter, not seeing it. Then if I remove the first ''S'' drive, the second one I plugged in flashes and appears as drive ''S'' updating the data in windows explorer. It is very strange as if windows would only sees one drive at a time. And like I said any SMD module plugg into a USB goes from ''E'' or whatever letter is the first one available and up to ''G''. Both drive work OK on a XP machine as ''E'' on the first, plug the other one and goes ''F''. Very strange. I sent a note to Dell and they referred me to reading the whole forum question that I might find an answer there, nice guys. Thks

mjc
05-03-2011, 07:47 PM
On the machine in question, boot to a Linux LiveCD and then plug the drives in...what happens?

classicsoftware
05-04-2011, 12:54 AM
From Windows 7., 4USB port, Dell I7, full equipped....I think I wasn't very clear, even if I change the drive letter to let's say ''S'' and reboot, that drive would stay as ''S'' and if a plug the other one, it search for a while and stop not assigning a letter, not seeing it. Then if I remove the first ''S'' drive, the second one I plugged in flashes and appears as drive ''S'' updating the data in windows explorer. It is very strange as if windows would only sees one drive at a time. And like I said any SMD module plugg into a USB goes from ''E'' or whatever letter is the first one available and up to ''G''. Both drive work OK on a XP machine as ''E'' on the first, plug the other one and goes ''F''. Very strange. I sent a note to Dell and they referred me to reading the whole forum question that I might find an answer there, nice guys. Thks

You didn't answer Paul's question. Please explain exactly what devices were plugged in. 2.5" drives, 3.5" drives?

Paul Komski
05-04-2011, 03:38 AM
I will just add that Windows does not treat fixed and removable drives in the same manner. The drive letters given to partitions on fixed drives by Windows remains the same - unless or untill any partitions are resized, moved or the mbr otherwise edited.

Removable drives are by default assigned drive letters dynamically. So the next available drive letter after C: will be assigned by Windows when a removable drive is attached. If it is removed thus freeing that drive-letter then the next drive attached gets this, now available, drive letter. If two externals are attached one after the other they should grab the next two available drive letters. Etc, etc.

If a letter higher up the alphabet is stipulated by the user from Disk Managemnt then Windows does link its Disk Signature to that particular drive letter and will re-assign it at each re-connection of that drive. However even that is not fixed in the Windows registry for all time and if, while removed, another drive is given that particular drive letter then when the one you had assigned manually is re-attached Windows will give it a brand new, next available drive letter, and not the one that has now been grabbed by another device.

boucbaz
05-04-2011, 11:27 PM
I am sorry, I thought I mention this on the first opening. 2.5 drive with USB power to drive motor. I am picking up everything you guys suggest and would try it all when I have acces to the PC again. One thing I didn't have the time to check since I had to leave customer place..Could it be that both drive have the same volume name? I think they were both alike, 500geg but can't remember the brand name. I will check this with cutomer tomorrow and bring a bootable CD next time, Ubuntu should be OK? Thks again.

classicsoftware
05-05-2011, 12:31 AM
It could be the 2.5" drive is drawing too much power. Does it have a dual USB plug at the end that would take up 2 USB ports?

mjc
05-05-2011, 01:52 AM
Ubuntu would be fine...

Paul Komski
05-05-2011, 08:29 AM
Could it be that both drive have the same volume name? I think they were both alike
That could be true but it is unimportant since Windows uses the Disk Signature or Volume ID to identify drives and partitions.

The Disk Signature (bytes 440 to 443 of the Master Boot Record) in conjunction with any partition's location and size on the drive is what is stored in the Windows Registry at HKLM\SYSTEM\MountedDevices and where the linkage of drive letters to any fixed drive or any removable drive currently attached is maintained.

The Volume ID or serial number can be ascertained by opening a Command Prompt windo and then entering the drive letter followed by a colon [eg x:] and then entering dir at the resultant prompt.

I repeat that I am sure the non-recognition of the second drive when both drives are attached simultaneously is not related to drive letter assignments and much more likely (particularly on a laptop) to be due to insufficient power to run two such drives that have no external power source at the same time.

PS Maybe read Existing USB ports may face trouble powering new breed of peripherals (http://www.zdnet.com/blog/berlind/existing-usb-ports-may-face-trouble-powering-new-breed-of-peripherals/736)

boucbaz
05-07-2011, 10:45 AM
OK Since everything now is pointing toward power deficiency, and I beleive you must be right, I'll sure try it next time I go down there with and external USB adaptor with power supply. Thks sir, I'll let you know as soon as I find out.