RHEL: Reserved space on a ext2/ext3/ext4 filesystem
# Tested on RHEL 6 & 7
# By default, when creating a new ext2/ext3/ext4 filesystem, five percent of the partition
# is reserved for the superuser, allowing root to carry out administrative tasks on the
# filesystem in the eventuality that F.S. becomes full.
# In the case of large partitions 5% may represent a lot of space so the percentage of
# reserved space may be reduced to the minimum, which is 1%
# We will use 'tune2fs' command with '-m' option, that allows us to modify it on line
# In this case I'm not saving much space as I'm using a small filesystem of only 1GB !
mkfs.ext3 /dev/rootvg/lv_apps # Valid for 'mkfs.ext2' and 'mkfs.ext4' commands too
[...]
13107 blocks (5.00%) reserved for the super user
[...]
tune2fs -l /dev/rootvg/lv_apps | grep -i "block count"
Block count: 262144
Reserved block count: 13107
mount /dev/rootvg/lv_apps /apps
df -k /apps
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/rootvg-lv_apps 999320 1320 945572 1% /apps
# Let's reduce reserved space to 1%:
tune2fs -m 1 /dev/rootvg/lv_apps
tune2fs 1.42.9 (28-Dec-2013)
Setting reserved blocks percentage to 1% (2621 blocks)
tune2fs -l /dev/rootvg/lv_apps | grep -i "block count"
Block count: 262144
Reserved block count: 2621
# Note that available space value is higher than before:
df -k /apps
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/rootvg-lv_apps 999320 1320 987516 1% /apps
Article Number: 67
Posted: Sun, May 27, 2018 8:47 PM
Last Updated: Sun, May 27, 2018 8:47 PM
Online URL: http://kb.ictbanking.net/article.php?id=67