Many individuals who are familiar with Linux file system would say “Ext3 does remove the Inode information of a file, and it is difficult to recover deleted data from Ext3 file system” when a normal data recovery application isn’t able to recover files then how a normal photo recovery application would be able to recover files from a Linux file system. Yes this is correct that Ext3 does remove the Inode information but it is quite easier to get the file out of ext2 (if we know more about file internals) to find out “bof” and “eof” of a specific file types (if it is stored contiguously). However recovery is still possible from ext3 in similar fashion.

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General Misconceptions

It is possible to recover (relatively easily) deleted files from ext2, but not from ext3. Ext3 wipes all the information. You gain something; you lose something by choosing either one.

Some tools are available to recover deleted photos from flashcards, but not from disks. The reason is simple: FAT32 is way simpler than ext3 or the Mac format.

But it is not like that, there is a unique thing about ext3 file system; even larger files that we think were fragmented can still be recovered as there is allocation information still left behind which allows recovering such large fragmented files.

Most of the data recovery software do not give recovery other then FAT32 could be lack of there understanding with other complex file systems, however recovery what generally people call it as “Signature search - a 8 byte unique signature of every file type” works mostly if the data has been saved contiguously but it fails when data is fragmented because allocation information and “eof” and size of the chunks cannot be located or technique to locate is not known.

There are lots of techniques available and what generally people try with available photo recovery applications a combination of signature search and file internal information to locate a file by catching its size and allocation. It means suppose we have a memory card which has been formatted and had lot of cr2 and crw’s, now what most of the recovery application would recover is crw’s and cr2’s but you would be surprised to see that they are able to recover JPG’s (It shows people have now learnt internals of a file type) as these RAW images have uncompressed JPG’s inside and can also be recovered without other specific information which is required to touch up an image (facility provided by RAW).

Most of the applications today are made to work either on Windows or MAC but good photo recovery software which knows how to search a signature and has a separate algorithms for each file type can recover files from any file system even when the file system is badly damaged or the drive is in RAW state. Recovery from RAID 0 and RAID 5 is an entirely special technique; we can consider RAID 1 to be a normal disk configuration as it another drive which is a mirror copy of your drive.

Finally the largest contributor of data loss is “Human Error” which causes 40-50% data loss globally as per the popular surveys.