Basic Linux Filesystems tutorial : ext2,ext3,ext4,JFS & XFS
There are three different methods of journaling commonly used in Linux, each with different levels of protection. These are shown in below Table.Journaling Filesystem MethodsMethodDescriptionData modeBoth inode and file data are journaled. Low risk of losing data, but poor performance.Ordered modeOnly inode data written to the journal, but not removed until file data is successfully written. Good compromise between performance and safety. Writeback mode Only inode data written to the journal, no control over when the file data is written. Higher risk of losing data, but still better than not using journaling.Limitation:The data mode journaling method is by far the safest for protecting data, but it is also the slowest. All of the data written to a storage device must be written twice, once to the journal, then again to the actual storage device. This can cause poor performance, especially for systems that do a lot of data writing.
Fredy Rouge 