Setting reserved blocks percentage to 1%

sudo tune2fs -m 1 /dev/sda4
According to tune2fs manual, reserved blocks are designed to keep your system from failing when you run out of space. Its reserves space for privileged processes such as daemons (like syslogd, for ex.) and other root level processes; also the reserved space can prevent the filesystem from fragmenting as it fills up. By default this is 5% regardless of the size of the partition. http://www.ducea.com/2008/03/04/ext3-reserved-blocks-percentage/

2
By: bassel
2009-09-14 21:11:55

These Might Interest You

  • 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


    -2
    dumpe2fs -h /dev/sdX
    dmmst19 · 2011-01-22 23:50:03 1
  • Just change /dev/sda1 to whatever your partition of interest is. This snippet should do the rest. Show Sample Output


    0
    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"%" }'
    MichalBryxi · 2011-03-14 20:46:56 0
  • This function make it easy to compute X/Y as a percentage. The name "wpoxiy" is an acronym of "what percentage of X is Y" Show Sample Output


    0
    function wpoxiy () { # What percentage of X is Y? Where percent/100 = X/Y => percent=100*X/Y # Example: wpoxiy 10 5 # 50.00% # Example: wpoxiy 30 10 # 33.33% echo $(bc <<< "scale=2; y=${1}; x=${2}; percent=x*100/y; percent")"%"; }
    mpb · 2018-06-10 22:43:20 0
  • This command securely erases all the unused blocks on a partition. The unused blocks are the "free space" on the partition. Some of these blocks will contain data from previously deleted files. You might want to use this if you are given access to an old computer and you do not know its provenance. The command could be used while booted from a LiveCD to clear freespace space on old HD. On modern Linux LiveCDs, the "ntfs-3g" system provides ReadWrite access to NTFS partitions thus enabling this method to also be used on Wind'ohs drives. NB depending on the size of the partition, this command could take a while to complete. Show Sample Output


    8
    # cd $partition; dd if=/dev/zero of=ShredUnusedBlocks bs=512M; shred -vzu ShredUnusedBlocks
    mpb · 2009-06-21 14:17:22 6

What Others Think

that's great, unless you're using another filesystem.
linuxrawkstar · 457 weeks and 2 days ago

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Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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