[Bug 1496210] Re: multipath-tools lacks the default settings for IBM 2810XIV storage system

[Mathieu Trudel-Lapierre]

** Description changed:

+ [Impact]
+ This impacts users of the IBM XIV storage system, which will not function properly with multipath in some circumstances given the missing default settings.
+ 
+ 
+ [Test case]
+ 1) Run 'multipath -l';
+ 2) Observe the line immediately below the device header; it should read similar to this:
+ size=32G features='1 queue_if_no_path' hwhandler='0' wp=rw
+ 
+ As opposed to without the patch:
+ size=32G features='0' hwhandler='0' wp=rw
+ 
+ 
+ Alternatively:
+ "If a multipath device is configured with features "1 queue_if_no_path", then any process that issues I/O will hang until one or more paths are restored."
+ 1) Remove all paths for a disk drive.
+ 2) Try to list files on the device.
+ 
+ 
+ [Regression Potential]
+ Given that this changes the default settings for the IBM 2810XIV storage systems, if some users of this hardware have come to rely on the incorrect settings provided, the behavior will change.
+ 
+ 
  ---Problem Description---
  multipath-tools is lacking the settings for IBM 2810XIV storage system
  
- Specially, the lack of queue_if_no_path is problematic on PowerVM LPM (live partition migration) operations, 
+ Specially, the lack of queue_if_no_path is problematic on PowerVM LPM (live partition migration) operations,
  because I/O errors will trigger filesystem errors, which on ext4 remount the fs in read-only mode, by default.
  
  Please incorporate this upstream commit in 15.10, 15.04 and 14.04:
-     864162b08067d3e55d52996846d10a046956c6d6 Add default values for IBM XIV Storage System.
+     864162b08067d3e55d52996846d10a046956c6d6 Add default values for IBM XIV Storage System.
  
  ---uname output---
  Ubuntu 15.10, 15.04, and 14.04
-  
+ 
  ---Additional Hardware Info---
- IBM 2810XIV Storage 
+ IBM 2810XIV Storage
  
  The upstream commit applies cleanly on 15.10 (0.5.0-based) and 15.04,
  14.04 (0.4.9-based).

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https://bugs.launchpad.net/bugs/1496210

Title:
  multipath-tools lacks the default settings for IBM 2810XIV storage
  system

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