Managing RAID on Linux

Creating an ext2 Filesystem

The mke2fs command is used to create ext2 filesystems on disk partitions or RAID devices. In addition, ext2 users have several other commands at their disposal to manage ext2 filesystems. Of particular note is tune2fs, which allows administrators to configure tunable ext2 parameters that don’t require re-initialization of the filesystem. tune2fs, as well as many other useful ext2 utilities, is available as part of the e2fsprogs package, which is included with most distributions and is available from http://e2fsprogs.sourceforge.net.

By default, mke2fs creates a filesystem on the specified device, using a block size of 4096 bytes.

# mke2fs /dev/md0

Use the -b flag to change the default block size.

# mke2fs -b 1024 /dev/md0

Normally, the number of inodes is automagically computed by mke2fs, based on the block size chosen (8192 bytes for each inode, by default). However, if the values that mke2fs computes are inadequate, the ratio of inodes to bytes can be altered as well. Note that the ratio of bytes to inodes should never be smaller than the block size. As the number of bytes per inode increases, you are left with fewer inodes; as the number decreases (or approaches the block size), more inodes are created. Here is an example that creates an ext2 filesystem with a block size of 1024 bytes and an inode ratio of 2048 bytes per inode, or one inode for every two blocks:

# mke2fs -b 1024 -i 2048 /dev/md0

This arrangement might be useful for a system where you expect ...