[dm-devel] Problems using multipath-tools & dm-multipath.

Caushik, Ramesh ramesh.caushik at intel.com
Tue Aug 17 23:57:47 UTC 2004


I am trying to use multipath-tools version 0.2.7 on a system running
2.6.6 kernel with the 2.6.6-rc2-udm1 dm patchset. The system has dual
port Qlogic 2312 controller, connected to a JBOD through a FC switch.  I
have the multipath drives configured as follows

- path_grouping_policy multibus
- getuid_callout    /bin/scsi_id -g -s
- path_checker    tur

I start multipathd; run multipath; run kpartx on a partioned drive dm-7
(this results in additional devmaps dm-11 & dm-12); I then run bonnie++
on the partition dm-11. While bonnie++ is in progress I disconnect one
of the FC ports from the switch. I expect 

-- the path switch to happen and the failed bios to be retried so the
application can run after a delay.

I find that the application waits for a long while, reports an I/O error
and quits. The behaviour is not different with other applications that
access the drive.
Is this supposed to work ? What could be the problem here ?

Secondly I connect the port back to the switch. I expect the path
re-connect to be discovered and the multipath device map to be restored.
But subsequent disk I/O through the same devmapped device (dm-11) sends
data only through one port (one that has always been connected). The
path restoration does not happen. Do you have thoughts on these.
Appreciate your feedback on this,

Ramesh.  
  

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