The Case of the missing Tractor GPS data

data recovery gps system

I recently received a call from a distressed farmer who had driven 4 hours from Southern Cross because his GPS device attached to his tractor had received a power surge and would no longer boot up. These devices are used by farmers to track where chemicals have been sprayed or seeded in specific paddocks, so they are unable to work without the information.

Even worse, the job was time-sensitive since the failure occurred as the farmer was spraying chemicals, which can lose their effectiveness once they have been mixed in the tractor’s tank. It is also impossible for the farmer to respray chemicals on areas that have already been sprayed, as the dual application will kill the soil.

GPS Guidance System requiring data recovery

The picture above is the X25 model of the GPS systems distributed by Top Con  Farm Guidance Systems. The actual system that was delivered to me was the X20 model which looked turn of the century in terms of architecture eg a celeron 1GHZ processor , DDR 266 Ram running Windows XP.  Storage of the whole system was contained on a not so whopping 2GB   Compact Flash Card.

datacrecovery of 2GB Compact Flash Card

The Cause of the Problem

The problem stemmed from the Compact Flash Card, which was formatted with NTFS and had a size of only 2GB. Based on my previous explanation of the FAT file system’s fragility, it is evident that the small size of the flash card did not allow for a duplicate MFT (Master File Table). For those unfamiliar with filesystems, the MFT acts as an index for all files on a storage medium and is crucial for opening or modifying files. It records the location of each file in blocks, which can be numerous for larger files. If the MFT becomes corrupted, it renders files unreadable and disrupts the system’s functionality.

Usually if you install any flavour of windows on a large enough drive / card 2 copies of the MFT are kept in case one gets corrupted however due to the small size of the Compact Flash Card there was only one copy and it was corrupted. This became obvious once we scanned the offending Compact Card with R-Studio and found there was no GPS data later than 2013.

Diagnosis

Fortunately the farmer had brought along an identical GPS system which was working and this allowed to me see the contents of the files which contained GPS data and as it turns out these files were  not  complicated. They  were simple text files called paddock which contained some header info and a series of GPS co-ordinates.  The picture below is an example of such data.

GPS Data recovered via raw data recovery

This then led me to believe I could perform a RAW RECOVERY and with luck recover the correct data. Raw recoverys are tricky as they rely on no information from the MFT but simply scan the whole storage medium block by block and attempts to identify files based on signatures.   The start of any file is easy to recognise however it’s end is not so easy and a successful RAW recovery requires that the file is stored contiguously on the disk however  if the file is a large file which has been edited many times then it is likely to have become fragmented and a raw recovery becomes difficult.

Data Recovery

After performing the RAW Recovery and sifting thru the large number of text files restored we found GPS data  which looked promising , of course the next trick is to reincorporate that data into a running system which we were fortunate to have.  Reincorporating data often  requires  some guess work on my behalf as the internal workings of a computer program can only be as good as the design of the program  , anyway we managed to bring up the required maps which looked familiar and which were dated correctly.

As a footnote I phoned the farmer approx a week after performing the recovery to check that all had gone well and I was pleased to here the recovery had been successful. It’s important , certainly for billing purposes,  that I validate the success of the work.

I cannot repeat this point too often that whenever a business or enterprise relies on data to operate then it is essential that it should have a backup and disaster recovery solution in place.