Dell EMC VMAX - Appendices and Support Information; Host Multipathing Software Configuration

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APPENDIX A: HOST MULTIPATHING SOFTWARE NOTES AND SETTINGS
This section describes best practices for using multi-pathing software in an NDM environment. Refer to the NDM Support Matrix for the
latest operating system and multi-pathing software combinations.
AIX NATIVE MULTI-PATHING SOFTWARE
For Native Multipathing on AIX, best practice is to use the following settings for MPIO:
algorithm = round_robin (other algorithms may also be used)
check_cmd = inquiry
queue_depth = 32
reserve_policy = PR_shared
LINUX NATIVE MULTI-PATHING SOFTWARE (DEVICE MAPPER)
Use reload/rescan multipath (multipath -r command) to detect and add new paths. Use the default /etc/multipath.conf file. The
following options are best practices to help the operating system and multi-pathing software detect path changes efficiently:
Path_grouping_policy multibus
path_checker tur
features "1 queue_if_no_path"
path_selector "round-robin 0"
no_path_retry 10
POWERPATH (VERSION 5.7 AND ABOVE)
Use the default Powerpath multi-path settings.
To detect, rescan, and configure new paths use the powermt config command. Specifically for Linux use
/etc/opt/emcpower/emcplun_linux scan all –noprompt may be used. This will rescan and perform a powermt config. Refer to the
PowerPath for Linux manual on http://support.emc.com for further information.
Use Powerpath commands/scripts to scan (on Linux: /usr/bin/rescan_scsi_bus.sh -r) and remove stale paths (powermt
check).
The powermt restore command can be used to detect path changes faster than PowerPath will discover them on its own.
Note: See Appendix B for important information regarding PowerPath and AIX 6.x with GPFS.
POWERPATH WITH SOLARIS
For Solaris with PowerPath, a cancel revert operation will end with the session in a “CancelFailed” state. The host paths to the source
array running 5876 must be recovered using cfgadm.
For example, to recover the dead paths one by one:
cfgadm -c configure c5::50000973f001d109
cfgadm -c configure c5::50000973f001d105
cfgadm -c configure c4::50000973f001d109
cfgadm -c configure c4::50000973f001d105
To recover all paths on a controller:
cfgadm –c configure c4