scsimgr leg_mapth_enable

[msaygak]

Hello!
I've read the scsimgr(1M) man page and found such example:

scsimgr set_attr -D /dev/rdisk/disk0 -a leg_mapth_enable=false

Can somebody explain me what this parameter mean?

[Turgay Cavdar · Accepted solution]

Hi,
"leg_mpath_enable is an attribute, which controls whether multi-pathing is enabled or disabled for legacy DSFs of a LUN. This tunable can be set at a global level or for a particular device. By default the SCSI stack explicitly set this attribute to true at the global level to enable by default multi-pathing for legacy DSFs of all LUNs."

Lets say you have a disk with two paths:
#ioscan -m dsf
Persistent DSF Legacy DSF(s)
========================================
/dev/rdisk/disk5 /dev/rdsk/c1t5d2
/dev/rdsk/c3t5d2

If you set leg_mpath_enable to true then make some io such as dd to /dev/rdsk/c1t5d2, then you will see both paths are used. If you set leg_mpath_enable to false then make some io such as dd to /dev/rdsk/c1t5d2, then you will see only one path is used.

[msaygak]

thanks!