Required attributes of LUNs for DMP devices

When the reserve_policy=single_path and reserve_lock=yes, the SCSI-2 reserve may be placed on the device, which affects I/O load balancing and performance. To prevent the impact to load balancing and performance, set the reserve_policy=no_reserve and reserve_lock=no for the devices that are managed by DMP.

These settings are also required for a cluster set-up.

Set the following attributes for LUNs

  1. Set the following attributes:

    • If the path has the reserve_policy attribute set, change the reserve_policy attribute to no_reserve for all the paths.

      # lsattr -E1 hdisk557 | grep res
      reserve_policy single_path
      Reserve Policy True
      <!--NeedCopy-->
      
      # chdev -l hdisk557 -a reserve_policy=no_reserve -P
      hdisk557 changed
      <!--NeedCopy-->
      
    • If the path has the reserve_lock attribute set, change the reserve_lock attribute to no.

      # lsattr -E1 hdisk558 | grep reserve_lock
      reserve_lock  yes
      Reserve Device on open True
      <!--NeedCopy-->
      
      # chdev -l hdisk558 -a reserve_lock=no -P
      hdisk558 changed
      <!--NeedCopy-->
      
  2. Reboot the system for the changes to take effect.

Required attributes of LUNs for DMP devices

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