"df" available space output - Linux

This is a discussion on "df" available space output - Linux ; Hello, I'm administering some RH 7.3 boxes and noticed that the "Available Space" output column is not a direct subtraction. For example, the output: """ Filesystem 1k-blocks Used Available Use% Mounted on /dev/cciss/c0d0p1 248911 98858 137202 42% / """ Calculating ...

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Thread: "df" available space output

  1. "df" available space output

    Hello,

    I'm administering some RH 7.3 boxes and noticed that the "Available
    Space" output column is not a direct subtraction. For example, the output:

    """
    Filesystem 1k-blocks Used Available Use% Mounted on
    /dev/cciss/c0d0p1 248911 98858 137202 42% /
    """

    Calculating "1k-blocks - Used": 248911 - 98858 = 150053

    Why doesn't it match the available space? I have been administering unix
    based servers for a while, but this was something I never paid close
    attention to because it was trivial. I'm assuming each file system has
    some data structure that's accounted for in the Available space.

    Thanks.

    --
    Mike

  2. Re: "df" available space output

    On 2006-05-25, Mike wrote:
    > Filesystem 1k-blocks Used Available Use% Mounted on
    > /dev/cciss/c0d0p1 248911 98858 137202 42% /
    >
    > Calculating "1k-blocks - Used": 248911 - 98858 = 150053
    >
    > Why doesn't it match the available space? I have been administering unix


    10% of the space (or something like that, the exact amount can be
    customized) is reserved for root use, so if your partition fills up you
    can still login as root and fix it.

    Davide

    --
    We are either doing something, or we are not. 'Talking about' is a
    subset of 'not'. -- from alt.sysadmin.recovery

  3. Re: "df" available space output

    On 2006-05-25, Mike wrote:
    > Hello,
    >
    > I'm administering some RH 7.3 boxes and noticed that the "Available
    > Space" output column is not a direct subtraction. For example, the output:
    >
    > """
    > Filesystem 1k-blocks Used Available Use% Mounted on
    > /dev/cciss/c0d0p1 248911 98858 137202 42% /
    > """
    >
    > Calculating "1k-blocks - Used": 248911 - 98858 = 150053
    >
    > Why doesn't it match the available space? I have been administering unix
    > based servers for a while, but this was something I never paid close
    > attention to because it was trivial. I'm assuming each file system has
    > some data structure that's accounted for in the Available space.


    On most systems, a portion of every file system is reserved for use
    by the superuser, and not included in the available space.

    --
    Chris F.A. Johnson, author
    Shell Scripting Recipes: A Problem-Solution Approach (2005, Apress)
    ===== My code in this post, if any, assumes the POSIX locale
    ===== and is released under the GNU General Public Licence

  4. Re: "df" available space output

    Chris F.A. Johnson wrote:
    > On 2006-05-25, Mike wrote:
    >> Hello,
    >>
    >> I'm administering some RH 7.3 boxes and noticed that the "Available
    >> Space" output column is not a direct subtraction. For example, the output:
    >>
    >> """
    >> Filesystem 1k-blocks Used Available Use% Mounted on
    >> /dev/cciss/c0d0p1 248911 98858 137202 42% /
    >> """
    >>
    >> Calculating "1k-blocks - Used": 248911 - 98858 = 150053
    >>
    >> Why doesn't it match the available space? I have been administering unix
    >> based servers for a while, but this was something I never paid close
    >> attention to because it was trivial. I'm assuming each file system has
    >> some data structure that's accounted for in the Available space.

    >
    > On most systems, a portion of every file system is reserved for use
    > by the superuser, and not included in the available space.
    >


    That would be a good thing for root to login

    Thanks, Davide/Chris.

    --
    Mike

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