[Bug 690387] Re: udev block naming breaks failover and sd kref release cycle

[Peter Petrakis]

** Description changed:

  Binary package hint: multipath-tools
  
- This was exposed on the Intel IMS SAN which is an ODM'd Promise Vtrak variant
- on 10.04 server. The SAN has Active/Standby capabilities and is configured for failover.
- It probably affects other SANs too.
+ This was exposed on the Intel IMS SAN which is an ODM'd Promise Vtrak
+ variant on 10.04 server. The SAN has Active/Standby capabilities and
+ is configured for failover. It probably affects other SANs too.
  
  Setup:
  multipath'd SAN consisting of SD block devices.
  
  Symptoms:
- On failover, multipath isn't gettng the right signals to tear down the defunct
- path. This was traced down to the fact that the path UDEV was presenting to
- multipath was different from what it was expecting. It simply dropped the request
- to gracefully remove the device, and instead responded to the SCSI mid-layer
- SD IO state change, SDEV_CANCEL/DEL which puts the device offline.
+ On failover, multipath isn't gettng the right signals to tear down
+ the defunct path. This was traced down to the fact that the path UDEV
+ was presenting to multipath was different from what it was expecting.
+ It simply dropped the request to gracefully remove the device, and
+ instead responded to the SCSI mid-layer SD IO state change,
+ SDEV_CANCEL/DEL which puts the device offline.
  
- Problem is device mapper still has an handle on the SD device, as can be seen
- from /sys/block/dm-x/slaves, and as a result, scsi_target_destroy is never called.
- The outward symptom of this is the SD suffix is not recycled because of course
- the previous reference never dropped.
+ Problem is device mapper still has an handle on the SD device, as
+ can be seen from /sys/block/dm-x/slaves, and as a result,
+ scsi_target_destroy is never called. The outward symptom of this
+ is the SD suffix is not recycled because of course the previous
+ reference never dropped.
  
  Solution:
- A fix was developed independently of upstream by Serge Hallyn, later it
- was found that it was fixed upstream, in 2007. The patch is.
+ A fix was developed independently of upstream by Serge Hallyn,
+ later it was found that it was fixed upstream, in 2008.
+ The patch is:
  
  commit 7fa7affc3d23dd9dc906804d22a61144bca9f9b9
  Author: Benjamin Marzinski <bmarzins at redhat.com>
  Date: Thu Dec 11 16:03:28 2008 -0600
  
-     Fix for uevent devpath handling
+     Fix for uevent devpath handling
  
-     This is necessary to make uevents work on fedora, since devpath appears as
-     something like:
-     '/devices/pci0000:00/0000:00:0a.0/0000:06:00.0/host11/rport-11:0-1/target11:0:1/11:0:1:0/block/s
+     This is necessary to make uevents work on fedora, since devpath appears as
+     something like:
+     '/devices/pci0000:00/0000:00:0a.0/0000:06:00.0/host11/rport-11:0-1/target11:0:1/11:0:1:0/block/s
  
-     It simply strips off the everything up to the /block.
+     It simply strips off the everything up to the /block.
  
-     Signed-off-by: Benjamin Marzinski <bmarzins at redhat.com>
+     Signed-off-by: Benjamin Marzinski <bmarzins at redhat.com>
  
  It integrates simply and can be found in PPAs here:
  ppa:peter-petrakis/storage

-- 
You received this bug notification because you are a member of Ubuntu
Server Team, which is subscribed to multipath-tools in ubuntu.
https://bugs.launchpad.net/bugs/690387

Title:
  udev block naming breaks failover and sd kref release cycle