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    SubjectRe: NBD client/server broken?
    Just to keep interested parties informed:

    Thanks to Steven Whitehouse I found out that the latest nbd client/server
    user space programs are in CVS on Sourceforge (the kernel nbd documentation
    needs updating to point to

    And I have just submitted a patch to Steven to make the nbd-server 64-bit
    clean on 32-bit machines and to allow proper auto detection of device size.
    Hopefully we will see it entering the CVS soon. Otherwise patch is
    available on request from me. (-:

    Mounting a NTFS 15GiB partition over nbd (using ntfs tng driver) gave me a
    data throughput of 7-10MiB/sec over 100MBit ethernet (going via switch and
    a hub) which is quite impressive. (-:

    Best regards,


    At 13:10 24/03/02, Anton Altaparmakov wrote:
    >I have been trying to get nbd to work, the server is 2.4.18-pre7-ac2 and
    >the client is 2.5.7, and the exported device is /dev/hda1 a 15GiB partition.
    >I found and downloaded nbd.14.tar.gz. Is this the latest and greatest?
    >Compiling the package gives several warnings and indeed the nbd-server
    >doesn't work. The size auto detection code is completely bogus because it
    >submits 64 bit variables via their address to system calls which only take
    >32 bit variables so you see silly things like
    >es = (u64)-1
    >turning into
    >es = 0xffffffff01d4b139
    >instead of
    >es = 0x000000000whatever
    >You either need to use 64 bit variants of the calls or you need to submit
    >a 32bit variable to the call, e.g. es32, and then expand it via es = (u64)es32.
    >So I got past this and fixed size detection for myself.
    >Now I get it to serve the first request but then it dies.
    >On the server I see:
    >[aia21@storm:~/nbd]$ ./nbd-server 5555 /dev/hda1 -r
    >Entering request loop!
    >1: *READ from 0 (0) len 4096, exp->buf, buf->net, +OK!
    >2: *[aia21@storm:~/nbd]$
    >And on the client I see:
    >[aia21@drop nbd]$ dd if=/dev/nd1 of=ffff bs=1024 count=8
    >NBD: receive - sock=-301251788 at buf=-65871580, size=16 returned 0.
    >NBD: Recv control failed.(result 0)
    >req should never be null
    >Kernel call returned.Closing: que, sock, done
    >NBD, minor 0: Request when not-ready.
    >dd: reading `/dev/nd0': Input/output error
    >4+0 records in
    >4+0 records out
    >[aia21@drop nbd]$
    >The contents of the 4kiB of data transmitted are correct so we are
    >definitely on the right track but something seems to be aborting the
    >request loop in the server program.
    >I will be looking into this as I _need_ this functionality very urgently
    >but I thought I would ask in case I have an out of data package of the nbd
    >utilities or someone has already fixed this and would like to share their
    >code with me...
    >Best regards,
    > "I've not lost my mind. It's backed up on tape somewhere." - Unknown
    >Anton Altaparmakov <aia21 at> (replace at with @)
    >Linux NTFS Maintainer / WWW:
    >ICQ: 8561279 / WWW:
    >To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    >the body of a message to
    >More majordomo info at
    >Please read the FAQ at

    "I've not lost my mind. It's backed up on tape somewhere." - Unknown
    Anton Altaparmakov <aia21 at> (replace at with @)
    Linux NTFS Maintainer / WWW:
    ICQ: 8561279 / WWW:

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