Home / ubuntu / Questions / 573211
Accepted
Minos
Asked: 2015-01-14 02:46:16 +0800 CST

What does the grey slice in disk usage represent?

  • 772

When I right click on Properties for my ext4 partition I get the following pie chart:

enter image description here

The meaning of the blue and white slices are fairly obvious, since they are in the legend to the right, but what does the grey slice represent? It's quite substantial and at least a couple of GB's in size.

nautilus

2 Answers

  1. Best Answer

    By default ext2, ext3 and ext4 reserve 5% of all space for the root user and to prevent fragmentation (see this mailing list). However as this particular disk is used for archiving data that doesn't change much, I have taken the liberty to change this percentage to 1%, using the command:

    sudo tune2fs -m 1 /dev/sdb

    the last item /dev/sdb reflecting the location of my disk. Behold:

    reserved space on disk is reduced

    • 6

  2. It shows the size of index table of your filesystem.

    In every HDD, you can not use the whole space for yourself.
    When any kind of partition is made on disk; to keep track of index of any file stored on it, parttion table is created to look up when we try to access any particular file.
    Not only that much information but all other information regarding each partitions' starting sector to end sector, sector size, structure, sector skewing information, etc...

    Like in FAT(File Allocation Table, you can store a file max of 4GB at a time, for greater than 4GB it won't allow you as it's capacity is of 4GB only.)

    There are different types of File-Systems, which uses different techniques to hold information, so that grey mark can be vary according to File-System you're using

    OR possibly it can be showing OS reserved space that used as SWAP area, for PAGING purpose, but I doubt it, if I'm wrong than correct it. Above answer is quite sure.

    • 0