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    SubjectRe: SCSI device numbering (was: Re: Ideas for v2.1
    On Thu, 20 Jun 1996, Eric Youngdale wrote:
    > Consider that some cards drive multiple channels. Currently some
    > cards support 2,

    Make that 5.

    > I have seen some people argue for solutions that work for the small
    > systems, but exclude the large systems. I believe that this is fundamentally
    > wrong, since the problems with dynamic address shifting grow as the number
    > of devices on the sysetem grow. We should be looking for solutions that
    > work in the case of large systems (with say 500 or more disk drives), and
    > then make sure that this works well for the small systems.
    > The scsidev program is basically sort of a band-aid until a better
    > solution arrives. I do believe that it should alleviate most of the
    > problems that people are having until that time comes.

    Another thing that would help would be to give very disk and partition a
    unique name in the system. That way it would make no more problems
    to move a drive from controller A channel B ID C to controller D channel E
    ID F, it would be possible to move disks around in the system
    without getting problems everytime if you forget to update the fstab.

    The fstab could look like this:
    root / ext2 defaults 1 1
    usr /usr ext2 defaults 1 2
    home1 /home/u1 ext2 defaults 1 2
    home2 /home/u2 ext2 defaults 1 2
    var /var ext2 defaults 1 2
    tmp /tmp ext2 defaults 1 2
    postgres /postgres ext2 defaults 1 2
    none /proc proc defaults 1 2
    swap1 none swap
    swap2 none swap
    swap3 none swap

    Convex (now HP supercomputer divison) has implemented this and it has proven
    to be very useful.

    > Note that with the current system, there can be a maximum of 16 disk
    > drives (since 16 * 16 partitions = 256 = max minor number). Clearly a larger
    > dev_t is needed, no matter how we do it.

    Yes, for example is one machine that is operating
    almost at this limit.

    > We need to somehow agree on how
    > large this needs to be, and *then* we need to fix the filesystems so that
    > they store a dev_t that is this large.

    My vote goes for 64+bits


    Michael Neuffer i-Connect.Net, a Division of iConnect Corp.
    mike@i-Connect.Net 13455 SW Allen Blvd., Suite 140
    503.677.2900 Beaverton, OR 97008

    "Linux was made by foreign terrorists to take money from true US
    companies like Microsoft." -- Some AOL'er.

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