Changing Reserved Space on EXT Partitions

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Contents 1 Description 2 Command 3 Extra Learning 4 References

Description

I was sick of the "slack space" allocated to the superuser on my ext drives for my fileserver. 5% is ok for 20 and 80GB drives, but for my 250+GB drives it was allocating around 12.5GB!

Command

This changes the reserved space to 10000 blocks

tune2fs -r 10000 /dev/hdl1

I ran this on a mounted filesystem without any corruption, but as with anything that modifies a FS it is much more highly recommended to dismount first.

Extra Learning

The tune2fs command is really useful in the hands of a skilled operator.

You can see by the list option that there we can tweak an awful lot, I've already tweaked the reserved blocks on this partition, and by multiplying the Reserved by the Block Size we can tell I am reserving about 40MB now.

midgard:~# tune2fs -l /dev/hdc1
tune2fs 1.35 (28-Feb-2004)
Filesystem volume name:   <none>
Last mounted on:          <not available>
Filesystem UUID:          faf1f756-fefd-4103-9025-e16df23bf4ef
Filesystem magic number:  0xEF53
Filesystem revision #:    1 (dynamic)
Filesystem features:      has_journal filetype needs_recovery sparse_super
Default mount options:    (none)
Filesystem state:         clean
Errors behavior:          Continue
Filesystem OS type:       Linux
Inode count:              30539776
Block count:              61049008
Reserved block count:     10000
Free blocks:              60082465
Free inodes:              30539765
First block:              0
Block size:               4096
Fragment size:            4096
Blocks per group:         32768
Fragments per group:      32768
Inodes per group:         16384
Inode blocks per group:   512
Filesystem created:       Wed Dec 20 06:30:23 2006
Last mount time:          Wed Dec 20 06:34:50 2006
Last write time:          Wed Dec 20 06:39:09 2006
Mount count:              1
Maximum mount count:      38
Last checked:             Wed Dec 20 06:30:23 2006
Check interval:           15552000 (6 months)
Next check after:         Mon Jun 18 06:30:23 2007
Reserved blocks uid:      0 (user root)
Reserved blocks gid:      0 (group root)
First inode:              11
Inode size:               128
Journal inode:            8
Default directory hash:   tea
Directory Hash Seed:      d48dc9d5-95c1-452a-9e8e-8fb1e00ab4b5
Journal backup:           inode blocks

References

I can't remember where I learned this from, it was quite a while ago.