Deleted files recovery for Linux
Linux operating systems provide a choice of file systems. Major file systems used by Linux include Ext2, Ext3 and Ext4, XFS, ReiserFS, JFS (JFS2) etc. These systems are interchangeable within the majority of Linux operating systems.
Ext2, Ext3, Ext4
This is 'native' file system of Linux operating system under active developments and improvements. Ext3 file system is just an extension to Ext2 using transactional file writing operations with so-called journal. Ext4 is the further development of Ext3 extended with optimized file allocation information support (extents) and support of 'extended file attributes'. This file system is often used as a 'root' file system for most Linux installations.
While deleting on Ext2, information about the file is partially wiped and deletion time is noted. Recovery of file content is possible without the file name, however. File name in a node reference is wiped. Deleted files can be recovered with any of UFS Explorer Software or Raise Data Recovery for Ext2/Ext3.
While deleting on Ext3/Ext4, the system wipes the information about file location as well. As this operation is performed via the journal, file recovery - even with a file name - is possible immediately after deletion with either Raise Data Recovery for Ext2/Ext3 or any of UFS Explorer software.
XFS file system
XFS is an old journalizing file system created by Silicon Graphics (SGI) originally for use with their IRIX-based servers, workstations and visualization systems. At present, XFS is also available to most Linux versions for creation of large data storage volumes. XFS file system is known for giving good performance when storing and accessing large files. Thus, it is applied in huge storage systems as well as re-used in network storages like Buffalo, Adaptec, Iomega, LaCie, Synology etc.
XFS features quite good support of deleted files recovery: files can be recovered, though file size might be different (larger). When a file is deleted from XFS, the system clears the information part of a file node and updates tree of free blocks. Thus, the information about the file name is not linked with a directory entry. Specially created for XFS Raise Data Recovery enables recovering data in this system.
As an alternative Linux file system ReiserFS aims at storing huge amount of small files. It has a good capability of file search and allows 'compact' files allocation by storing file tails or small files along with metadata without using large file system blocks for this. When a file is deleted from ReiserFS, the system updates its S+-tree to exclude the file and updates the information about free space on a map. Due to considerable information duplication (including journal) Reiser FS has strong chances for deleted files recovery with exact size, location and name. Raise Data Recovery for ReiserFS or any other UFS Explorer software suit for this case of data recovery.
This file system was developed by IBM for their powerful computing systems. Saying JFS one usually means its second version (JFS2). Currently this file system is open-source and implemented in most modern Linux versions. JFS has good chances for recovery of file contents. However, file names might be recovered incorrectly in many cases. When a file is deleted from JFS (JFS2), the system updates object use counter and releases an inode in inode use map. Directory is rebuilt to reflect changes. File recovery is possible with Raise Data Recovery for JFS or any other UFS Explorer software.
Note: Like any deleted data recovery, file recovery from these file systems is possible before actual disk space is re-used for a new file.