One Linux Formatting Tip I Bet You Didn’t Know

By Angsuman Chakraborty, Gaea News Network
Monday, October 13, 2008

You probably know how you can format a Linux partition:

mkfs.ext3 /dev/hda

This formats the partition with ext3 file system. However did you know how to extract maximum space out of this partition, especially if it a large partition?

How to maximize available space in a partition

Enter the magical -m option. If the file system becomes filled and there is no more space to write, it is basically unusable because the operating system is constantly writing to disk. By default, five percent of the partition is reserved for use by the root user. This allows root to conduct administrative activities on the partition and perhaps move some data off. Firstly, this is most critical when the partition contains / or home directories. For pure data partitions, this is just lost space. Five percent of a 250Gb partition is 12.5 Gb. Especially in the case of large partitions, it is safe to set the reserved space to the minimum, which is one percent.
mkfs.ext3 -m 1 /dev/hdb1
creates a file system with only 1% of its space reserved for the root user.

Note: You can use tune2fs -m later to adjust the reserved blocks after data is loaded on the partition.

Bonus tip: How to label a partition

Use -L with mkfs.ext3 to add a label to the partition. You can later refer to this label instead of the device name when mounting. This provides the same functionality as e2label which can be used to label a partition later.

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