Linux file systems
- File systems provides a means of organizing data on storage devices.
Basic concepts in File Systems
i-Nodes
- Inode is a data structure and it defines file or a directory on the filesystem
- Inodes point to blocks that makeup a file
- The control information in the i-node includes
- file owner
- time of last acess
- creation time
- group Id
- Each directory gets an i-node & inode points to the datablocks containing information (filenames & i-nodes)
Block
- Data on ext* file system is organized into block, A block is sequence of bytes.
- Each block smallest addressable unit in storage device
- Blocks are in turn grouped into block groups & each block group consists of superblock.
- Superblock is first piece of information read from disk, This small datastructure reveals information such as
- available space
- location of i-node
Filesystems in linux
- The popular filesystems in linux are
- ext4:
- Supports maximum file system size of 1EB (exabyte)
- Supports maximum individual file sizes up to 16TB each.
- XFS
- Journal base 64 bit file system.
- Supports files systems as large as 8EiB (Exbibytes == 8 million terrabytes)
- Supports maximum individual file sizes up to 8EiB (Exbibytes == 8 million terrabytes)
- Btrfs:
- Next generation Linux file system. In addition to all the features of ext4, Btrfs supports
- Dynamic i-node allocation and transparent compressing
- Online file system checking
- Buit-in RAID functions such as mirroring & stripping
- Next generation Linux file system. In addition to all the features of ext4, Btrfs supports
- ext4:
Commands useful for storage
- Disk Utilization:
- The du command allows you to determine disk utilization on a directory-by-directory basis
- For du examples Refer Here
- To display total amount of space used by all the files & directories in PWD
du -sh .
- Disk free:
- The df program displays the amount of free space available on the mounted file system.
- To show free space for all locally mounted drives use this command
sudo df -l
- To show the free space in human-readable format
sudo df -h
Next steps
- Mounting & un mounting in linux
- Making file systems
- Partitions using LVM (Logical Volume Manager)
Exercise:
- Please find out about a tool called as rsync