what is /dev/root - HP UX

This is a discussion on what is /dev/root - HP UX ; Hi, When I do bdf, or look at fstab or mnttab, I see following - /dev/vg00/lvol1 .... / .... vxfs but when I look at the debugger (kwdb, q4) and load the mount list through (load struct vfs from rootvfs ...

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Thread: what is /dev/root

  1. what is /dev/root

    Hi,
    When I do bdf, or look at fstab or mnttab, I see following -

    /dev/vg00/lvol1 .... / .... vxfs

    but when I look at the debugger (kwdb, q4) and load the mount list
    through
    (load struct vfs from rootvfs next vfs_next max 100)
    and look at the rootvfs data, I see /dev/root,... and in the whole list
    I
    dont see /dev/vg00/lvol1 at all.

    Also both /dev/root, and /dev/vg00/lvol1 have different major numbers
    also.... I am just wondering what is the differences and similarities
    between them ?

    Well this behaviour is on IA 11.23 machine.

    Thanks


  2. Re: what is /dev/root

    iam.techy@gmail.com wrote:
    > Hi,
    > When I do bdf, or look at fstab or mnttab, I see following -
    >
    > /dev/vg00/lvol1 .... / .... vxfs
    >
    > but when I look at the debugger (kwdb, q4) and load the mount list
    > through
    > (load struct vfs from rootvfs next vfs_next max 100)
    > and look at the rootvfs data, I see /dev/root,... and in the whole list
    > I
    > dont see /dev/vg00/lvol1 at all.
    >
    > Also both /dev/root, and /dev/vg00/lvol1 have different major numbers
    > also.... I am just wondering what is the differences and similarities
    > between them ?
    >
    > Well this behaviour is on IA 11.23 machine.
    >
    > Thanks
    >

    remove /dev/mnttab and run mountall, then it will show up as /dev/lvol1.
    If mnttab gets corrupted it will cause this behaviour.

  3. Re: what is /dev/root


    Alan D Johnson wrote:
    > iam.techy@gmail.com wrote:
    > > Hi,
    > > When I do bdf, or look at fstab or mnttab, I see following -
    > >
    > > /dev/vg00/lvol1 .... / .... vxfs
    > >
    > > but when I look at the debugger (kwdb, q4) and load the mount list
    > > through
    > > (load struct vfs from rootvfs next vfs_next max 100)
    > > and look at the rootvfs data, I see /dev/root,... and in the whole list
    > > I
    > > dont see /dev/vg00/lvol1 at all.
    > >
    > > Also both /dev/root, and /dev/vg00/lvol1 have different major numbers
    > > also.... I am just wondering what is the differences and similarities
    > > between them ?
    > >
    > > Well this behaviour is on IA 11.23 machine.
    > >
    > > Thanks
    > >

    > remove /dev/mnttab and run mountall, then it will show up as /dev/lvol1.
    > If mnttab gets corrupted it will cause this behaviour.


    No This also doesnt work, I removed /etc/mnttab [though I knew it is nt
    corrupted], and did mount -a (mountall), cat /etc/mnttab (and mount
    command, or bdf) still shows the same output with /dev/vg00/lvol1...
    and debugger still shows /dev/root


  4. Re: what is /dev/root

    iam.techy@gmail.com wrote:
    > When I do bdf, or look at fstab or mnttab, I see following -
    >
    > /dev/vg00/lvol1 .... / .... vxfs
    >
    > but when I look at the debugger (kwdb, q4) and load the mount list
    > through
    > (load struct vfs from rootvfs next vfs_next max 100)
    > and look at the rootvfs data, I see /dev/root,... and in the whole list
    > I
    > dont see /dev/vg00/lvol1 at all.
    >
    > Also both /dev/root, and /dev/vg00/lvol1 have different major numbers
    > also.... I am just wondering what is the differences and similarities
    > between them ?


    /dev/root is handled by VFS layer, where as VG is handled
    by LVM lv driver. /dev/root is mostly used in maintenance
    mode (such as LVM maintenance mode). This device special
    file can be used to by pass LVM.

    hth,

    --vishwas.

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