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    SubjectRe: raid1 with nbd member hangs MD on SLES10 and RHEL5
    Mike Snitzer wrote:
    > On 6/14/07, Paul Clements <> wrote:
    >> Mike Snitzer wrote:
    >> > Here are the steps to reproduce reliably on SLES10 SP1:
    >> > 1) establish a raid1 mirror (md0) using one local member (sdc1) and
    >> > one remote member (nbd0)
    >> > 2) power off the remote machine, whereby severing nbd0's connection
    >> > 3) perform IO to the filesystem that is on the md0 device to enduce
    >> > the MD layer to mark the nbd device as "faulty"
    >> > 4) cat /proc/mdstat hangs, sysrq trace was collected
    >> That's working as designed. NBD works over TCP. You're going to have to
    >> wait for TCP to time out before an error occurs. Until then I/O will
    >> hang.
    > With (uni-processor) I've not seen NBD hang in the
    > kernel like I am with RHEL5 and SLES10. This hang (tcp timeout) is
    > indefinite oh RHEL5 and ~5min on SLES10.
    > Should/can I be playing with TCP timeout values? Why was this not a
    > concern with; I was able to "feel" the nbd
    > connection break immediately; no MD superblock update hangs, no
    > longwinded (or indefinite) TCP timeout.

    I don't know. I've never seen nbd immediately start returning I/O
    errors. Perhaps something was different about the configuration?
    If the other other machine rebooted quickly, for instance, you'd get a
    connection reset, which would kill the nbd connection.

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      Last update: 2007-06-15 03:19    [W:0.021 / U:3.232 seconds]
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