Check the reserved block percentage of an Ext2/3 filesystem

dumpe2fs -h /dev/sda1 2> /dev/null | awk -F ':' '{ if($1 == "Reserved block count") { rescnt=$2 } } { if($1 == "Block count") { blkcnt=$2 } } END { print "Reserved blocks: "(rescnt/blkcnt)*100"%" }'

Just change /dev/sda1 to whatever your partition of interest is. This snippet should do the rest.

Sample Output

Reserved blocks: 5%

By: MichalBryxi

2011-03-14 20:46:56

awk dumpe2fs ext3

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Check the reserved block percentage of an Ext2/3 filesystem

You are probably aware that some percent of disk space on an ext2/ext3 file system is reserved for root (typically 5%). As documented elsewhere this can be reduced to 1% with tune2fs -m 1 /dev/sdX (where X = drive/partition, like /dev/sda1) but how do you check to see what the existing reserved block percentage actually is before making the change? You can find that with dumpe2fs -h /dev/sdX You get a raw block count and reserved block count, from which you can calculate the percentage. In the example here you can easily see that it's currently 1%, so you won't get any more available space by setting it to 1% again. FYI If your disks are IDE instead of SCSI, your filesystems will be /dev/hdX instead of /dev/sdX. Show Sample Output
This is sample output - yours may be different.
```
...
Block count:              137128831
Reserved block count:     1371288
...
```
-2

dumpe2fs -h /dev/sdX

dmmst19 · 2011-01-22 23:50:03 6

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