Reformat JBOD drive from FAT32 to ext3

Q I recently purchased a 1TB USB desktop hard drive from Iomega, which consists of two 500GB drives strung together using JBOD so that it appears as a single 1TB volume. Naturally it came pre-formatted with a single FAT32 filesystem, which is fine except that I want to store files bigger than 4GB and also have proper file permissions. Can I reformat the drive to ext3 (if possible with multiple partitions) without breaking the JBOD configuration, and if so is it then just a case of firing up a standard disk partitioning tool like DiskDrake and proceeding as normal? I haven't risked trying it yet as I don't want to end up with a single 500GB drive or worse!

A When you connect this drive to your computer, what does dmesg or syslog show? Does it show one drive or two? If it shows as a single drive, the JBOD (Just a Bunch Of Disks) magic is handled by the drive's firmware and the internal configuration is largely irrelevant. If two drives show up - say, sda and sdb - the joining of the disks is handled by software. From the description on the manufacturer's website, it appears that the former setup is used and the JBOD configuration is internal. In that case, you can safely treat the device as it it were a single drive, the number of drives inside the case is of no more relevance than the number of platters in a drive.

1TB drives are still noticeably more expensive per MB than 500GB ones, so this is probably a cost-saving measure - even with the extra cost of the firmware to combine the drives, they would be cheaper to manufacture. Run your favourite disk partitioner - DiskDrake, cfdisk or GParted - on the disk and see what it shows. If it shows a single 1TB drive, you should have no problems partitioning it. To get a definitive answer, you would have to contact Iomega using one of the addresses listed at and give the exact model number of your drive, but I would feel safe partitioning it if it were my drive.

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