Root-on-NFS /dev has incorrect major/minor numbers - Questions

This is a discussion on Root-on-NFS /dev has incorrect major/minor numbers - Questions ; Hi there, I've been nutting out this problem that I've come across after upgrading one of my linux machines that acts as an NFS server to another machine on which I am trying to install Debian 3.0 in a completely ...

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Thread: Root-on-NFS /dev has incorrect major/minor numbers

  1. Root-on-NFS /dev has incorrect major/minor numbers

    Hi there,

    I've been nutting out this problem that I've come across after upgrading
    one of my linux machines that acts as an NFS server to another machine
    on which I am trying to install Debian 3.0 in a completely diskless way.

    The problem is essentially incorrect major/minor numbers in the /dev
    directory on the remote client's root filesystem which happens to be
    mounted over NFS from the server. After much searching and tidbits of
    information from various places, it would appear to be something to do
    with how NFS v2 and v3 handle device files.

    Mounting the filesystem using NFSv2 gives the client properly formed
    device files with correct major/minor numbers. Mounting using NFSv3
    appears to copy the major number over the minor number and thus most
    devices don't work.

    Does anyone know if this seemingly incorrect behaviour is intentional?
    I'm using 2.2.20 on the client and 2.4.20 on the server. Is it likely to
    be fixed, or should I be going about it completely differently (e.g.
    /dev on ramdisk or something similar)?

    Cheers,
    Oliver


  2. Re: Root-on-NFS /dev has incorrect major/minor numbers

    Oliver Hookins wrote:
    >
    > Mounting the filesystem using NFSv2 gives the client properly formed
    > device files with correct major/minor numbers. Mounting using NFSv3
    > appears to copy the major number over the minor number and thus most
    > devices don't work.


    What versions does the server support? If the server is only v2 that
    might explain it.

    >
    > Does anyone know if this seemingly incorrect behaviour is intentional?
    > I'm using 2.2.20 on the client and 2.4.20 on the server. Is it likely to
    > be fixed, or should I be going about it completely differently (e.g.
    > /dev on ramdisk or something similar)?


    I was unable to duplicate your problem. I was using v3 on server and
    client. I suspect there is something wrong with your configuration.


  3. Re: Root-on-NFS /dev has incorrect major/minor numbers

    Grant wrote:
    >
    > What versions does the server support? If the server is only v2 that
    > might explain it.


    The server supports v2 and v3.

    [root@hektor root]# nfsstat
    Server rpc stats:
    calls badcalls badauth badclnt xdrcall
    13674 0 0 0 0
    Server nfs v2:
    null getattr setattr root lookup readlink
    1 0% 2 0% 0 0% 0 0% 1148 98% 2 0%
    read wrcache write create remove rename
    0 0% 0 0% 0 0% 0 0% 0 0% 0 0%
    link symlink mkdir rmdir readdir fsstat
    0 0% 0 0% 0 0% 0 0% 7 0% 1 0%

    Server nfs v3:
    null getattr setattr lookup access readlink
    1 0% 3 0% 8 0% 3614 28% 8397 67% 8 0%
    read write create mkdir symlink mknod
    424 3% 8 0% 0 0% 0 0% 0 0% 0 0%
    remove rmdir rename link readdir readdirplus
    0 0% 0 0% 0 0% 0 0% 36 0% 0 0%
    fsstat fsinfo pathconf commit
    3 0% 3 0% 0 0% 8 0%

    >> Does anyone know if this seemingly incorrect behaviour is intentional?
    >> I'm using 2.2.20 on the client and 2.4.20 on the server. Is it likely
    >> to be fixed, or should I be going about it completely differently
    >> (e.g. /dev on ramdisk or something similar)?

    >
    > I was unable to duplicate your problem. I was using v3 on server and
    > client. I suspect there is something wrong with your configuration.


    The server is a pretty fresh load of Redhat 7.3 with updates. As far as
    configuration goes, /etc/exports reads as follows:

    /tftpboot/192.168.1.170 192.168.1.170(rw,no_root_squash)

    I actually had it all working properly when I had Redhat 7.1 running on
    the server, but I have been assuming there were changes made in the
    kernel to the NFS server between those releases which is causing these
    problems. I know that going back to 2.4.18 doesn't change it.

    The client is mounting with vers=3,dev,rw. I'd be glad if it's just a
    configuration issue but I can't think of what it might be - I've
    literally set it up exactly the same way as it was running before.

    Oliver


  4. Re: Root-on-NFS /dev has incorrect major/minor numbers

    Grant wrote:
    >
    > I was unable to duplicate your problem. I was using v3 on server and
    > client. I suspect there is something wrong with your configuration.
    >


    Could I ask the version of kernel you are running on your server and
    client, and if they are custom kernels or precompiled distro-specific?

    Thanks,
    Oliver



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