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    SubjectRe: knfsd and submounts
    Miquel van Smoorenburg wrote:
    > According to Dominik Kubla:
    > > Hmm, let's see. says:
    > >
    > > Emulate Sun NFS daemon
    > > If you would like for the server to allow clients to access
    > > directories that are mount points on the local filesystem (this is
    > > how nfsd behaves on Sun systems), say yes here. If unsure, say N.
    > >
    > > Ah, I see! That's the equivalent to unfsd's "--re-export" option, right?
    > No, I don't think so ..
    > Say you have /usr/fnord on your root filesystem. Then, /usr gets mounted
    > and /usr/fnord dissapears. When you export / over NFS, /usr is not exported.
    > Do you now get to see /usr/fnord on the NFS client, or not? _That_ is
    > what the option CONFIG_NFSD_SUN does, at least if I'm understanding
    > things correctly.

    Mine works thusly. I've got the following mount points:
    /dev/hda1 on / type ext2 (rw)
    /dev/hda6 on /home type ext2 (rw)
    /dev/hda2 on /usr type ext2 (rw)
    /dev/hda5 on /var type ext2 (rw)

    In /etc/exports, one of my shares is:

    / reliant(rw,no_root_squash) excelsior

    Now, locally, I do an ls:
    [root@ds9 /root]# ls /usr
    X11R6/ doc/ i386-redhat-linux/ info/ local/ reliant/
    bin/ etc/ i486-linux-libc5/ lib/ lost+found/ sbin/
    dict/ games/ include/ libexec/ man/ share/

    From reliant, I mount the ds9:/ export and do an ls of the
    <mountpoint>/usr directory:
    Connection to ds9 closed.
    me2v:reliant me2v$ su -c 'mount ds9:/ /mnt/ds9'
    me2v:reliant me2v$ ls /mnt/ds9/usr
    me2v:reliant me2v$

    Now, the kernel was configured with the following Network File System
    # Network File Systems
    # CONFIG_CODA_FS is not set
    # CONFIG_NCP_FS is not set

    Plainly, the CONFIG_NFSD_SUN does something other than what the says it does. I'm not sure what, but it *doesn't* allow
    submounts to be viewed as part of the total exported filesystem; only
    the physical partition is exported, and not any of the other partitions
    mounted on the exported partition (I know, we export directories, by for
    clarity's sake...)

    > > So the only way to export say a multigigabyte FTP server without to much
    > > hassle is to put the filesystem on a software RAID or LVM. (Which i had
    > > so i did not experience that particular problem in the first place.)
    > > That's suboptimal.
    > Yup..

    Yes, definitely sub-optimal. However, also, definitely something to
    drool over... ;)

    Matthew Vanecek
    Course of Study:
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    For answers type: perl -e 'print
    For 93 million miles, there is nothing between the sun and my shadow
    except me. I'm always getting in the way of something...

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