EMC Powerpath and other third party multipathing drivers are not supported with regards to "thin reclamation" even with Veritas Volume manager 5.1 SP1 onwards
Article ID: 100005878
Updated On:
Cause
Whereby EMC PowerPath is the multipathing driver for the related "thin provisioned" luns, and "thin reclamation" is required, the configuration is not supported even with Veritas Volume Manager 5.1 SP1.
For more information, refer HCL at https://sort.veritas.com/hcl
Inconsistent behaviour with relation to thin/thinrclm devices may be observed with EMC PowerPath and the other third party multipathing drivers, so Veritas DMP is an essential requirement for the functionality to operate consistently in Veritas Volume Manager environments.
Resolution
From an interoperability standpoint, vxdisk -o thin list was never intended to work with multipathing drivers outside the scope of Veritas DMP.
The "thin reclamation" feature is therefore only supported with Veritas DMP and VxVM.
With 5.1 SP1, the extended attribute content displayed by vxdisk -e list for VxVM related devices is suppressed for all other multipathing drivers except Veritas DMP.
Applies To
Cross platform
Special Note: EMC/VMAX array with flarecode 5875 and Storage Foundation 5.1 SP1
Issue/Introduction
With the proper hardware specific Array Support Library (ASL), Storage Foundation automatically discovers luns that are thin and luns that are thinrclm. In the event that the ASL for a given storage array does not discover these device attributes, they can be set manually by a system administrator, thereby allowing the devices to be used for SmartMove and Thin Reclamation.
SmartMove is the ability to migrate from thick to thin online and automatically reclaim the unused space in the VxFS file system originally supported by the thick devices. SmartMove can also be used to keep thin storage thin when it is used by host based mirrors. By default, SmartMove is used for all volumes that contain one or more thin or thinrclm device.
Thin Reclamation is the ability to reclaim unused space on thinrclm devices online, without modifying host, SAN or storage array configurations.
The VxVM (Veritas Volume Manager) "vxdisk -o thin list" command is used to display per lun specific information for TP (Thin Provisioned) luns with relation to Veritas DMP only.
Sample output for an EMC VMAX array
EMC PowerPath: Not supported. # vxdisk -o thin list
DEVICE SIZE(mb) PHYS_ALLOC(mb) GROUP TYPE
emcpower0s2 2062 N/A arraydg thinrclm
emcpower1s2 2062 N/A arraydg thinrclm
emcpower2s2 2062 N/A arraydg thinrclm
emcpower3s2 2062 N/A arraydg thinrclm
emcpower4s2 2062 N/A arraydg thinrclm
emcpower5s2 2062 N/A arraydg thinrclm
emcpower6s2 2062 N/A - thinrclm
emcpower7s2 2062 N/A - thinrclm
emcpower8s2 2062 N/A - thinrclm
emcpower9s2 2062 N/A - thinrclm
VERITAS DMP: Supported configuration.
# vxdisk -o thin list
DEVICE SIZE(mb) PHYS_ALLOC(mb) GROUP TYPE
emc0_165a 2062 N/A - thinrclm
emc0_165b 2062 N/A - thinrclm
emc0_165c 2062 N/A - thinrclm
emc0_165d 2062 N/A - thinrclm
emc0_165e 2062 N/A - thinrclm
emc0_1655 2062 N/A - thinrclm
emc0_1656 2062 N/A - thinrclm
emc0_1657 2062 N/A - thinrclm
emc0_1658 2062 N/A - thinrclm
emc0_1659 2062 N/A - thinrclm
Note: The PHYS_ALLOC column in the "vxdisk -o thin list" output lists "N/A" instead of the size of the physical allocation.
EMC's SYMMETRIX/VMAX does not report the physilcal allocation content to Veritas Volume Manager (VxVM) as EMC reporting is all "out-of-band" communication for thin allocation. Thus the behavior of the PHYS_ALLOC column reporting "N/A" is considered expected behaviour.
