Messages in this thread | | | Date | Thu, 14 Jun 2007 21:10:46 -0400 | From | "Mike Snitzer" <> | Subject | Re: raid1 with nbd member hangs MD on SLES10 and RHEL5 |
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On 6/14/07, Paul Clements <paul.clements@steeleye.com> 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 kernel.org 2.6.15.7 (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 kernel.org 2.6.15.7; I was able to "feel" the nbd connection break immediately; no MD superblock update hangs, no longwinded (or indefinite) TCP timeout.
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