My usb mass storage device are not showing all 4 drive its show only 1 drive but

my usb storage has 4 drive, but in my pc its show only 1 drive and any other computer its show all 4 drive

Windows 7 hides empty drives by default. Check the View tab under the Folder Options menu and make sure the "Hide empty drives in the Computer folder" is not checked.

Pls help what to do . . . .

How is your setup?

Is the USB storage a generic third party case such as EIDE to USB or eSATA to USB?

Or is it some such as a Western Digital MyBook or a Seagate Agent or some other brand name?

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If it's one of the Brand name USB storage units, which Brand and model is it?

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If it's a Generic USB Storage unit, What type is it, EIDE or eSATA and how many physical drives do you have in the enclosure?

Earlier you spoke of 4 drives?
If the Unit has only one Physical drive, do you mean to say that the drive has 4 separate partitions?

If multiple partitions, What file system is used for each one or are they all the same?

FAT, FAT16, FAT32, NTFS, EXT, EXT2, EXT3 (probably omitting some here)

There could be corruption on the drive which may be causing the system not to be able to read the other partitions. If this is the case, a Disk scan may be able to fix the errors.

Another thing, in the Disk Management console, the drives you are unable to view, if there is a yellow exclamation mark to the left of the drive in the bottom pane, then you would need to right click over the exclamation mark and select initialize drive.