Large USB Disk Data Recovery

This page is about the recovery of data from large (1TB) USB disks. There aren't actually any disk drives this large (yet) so these devices are actually two 500GB IDE drives concatenated.

Someone came to me with one of these drives that had suffered a failure of its USB interface; the disk themselves were fine, but the data was needed urgently and there was no spare enclosure into which to transplant the drives.

It is possible to read these devices using the Device Mapper in Linux. This tool combines a set of block devices into a single block device by mapping sectors from one to the other. If your disks had 100 blocks each, the mapping would look like this:

mapping of big disk

In practice, there'll be a partition table at the start of the disk; to get hold of the filesystem, we'll need to ignore the sectors on the first track (typically sectors 0–63).

Peter Benie <>