I know that this feature dates back 20 years but I still would like to find outWhat is the purpose of the reserved blocks in ext2/3/4 filesystems?
ext2/3/4 reserved blocks percentage purpose
filesystems;ext4;ext3;ext2
The man page of tune2fs gives you an explanation:Reserving some number of filesystem blocks for use by privileged processes is done to avoid filesystem fragmentation, and to allow system daemons, such as syslogd(8), to continue to function correctly after non-privileged processes are prevented from writing to the filesystem.It also acts as a failsafe; if for some reason the normal users and their programs fill up the disk up to 100%, you might not even be able to login and/or sync files before deleting them. By reserving some blocks to root, the system ensures you can always correct the situation.In practice, 5% is an old default and may be too much if your hard drive is big enough. You can change that value using the previously mentioned tune2fs tool, but be sure to read its man page first!