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    SubjectRe: Linux mdadm superblock question.
    Henrique de Moraes Holschuh wrote:
    > On Sat, 13 Feb 2010, Michael Evans wrote:
    >
    >> I remember hearing that 1.x had /no/ plans for kernel level
    >> auto-detection ever. That can be accomplished in early-userspace
    >> leaving the code in the kernel much less complex, and therefore far
    >> more reliable.
    >>
    >
    > Yes, it is far more reliable kernel side, if only because it doesn't do
    > anything.
    >
    > But the userspace reliability is _not_ good. initrds are a source of
    > problems the moment things start to go wrong, and that's when they are not
    > the problem themselves.
    >
    > And the end result is a system that needs manual intervention to get its
    > root filesystem back.
    >
    > In my experience, every time we moved critical codepaths to userspace, we
    > ended up decreasing the *overall* system reliability.
    >
    I don't see it like this.
    You have the same chance to screw up the system by making mistakes in
    the files in /etc, in the networking config, the firewall, the server
    applications...
    (note: I speak for Debian/Ubuntu, redhat's initramfs I think is more messy.)
    1.x autodetection worked great for me in initramfs. Basically you only
    need /etc/mdadm/mdadm.conf copied to initramfs (via update-initramfs),
    the rest is done by Debian/Ubuntu standard initramfs procedure.
    Also consider 1.x allows to choose which arrays are autoassembled
    (hostname written in the array name equal to hostname in the machine or
    specified in mdadm.conf): this is more precise than 0.9 which
    autoassembles all, I think.


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