Re: Interpreting DM-Multipath output in Linux

Posted by ErmanArslansOracleBlog on Jan 24, 2019; 8:50am
URL: http://erman-arslan-s-oracle-forum.124.s1.nabble.com/Interpreting-DM-Multipath-output-in-Linux-tp7143p7149.html

sdhm , sdcy , sdff  and sdar are the block device names.
They all point to the same device.. So you can think that they are identical.
"They are pointing to the same  device."
Multipath devices are like the logical devices, they are on top of sd devices.
They are orchestrating the I/O to the sd disks..
sd disks are pointing to the same devices, but they are pointing to the same device using different paths.
(through Different HBAs, different cables or different SAN switches)
So, multipath and multipath logical devices operate on /dev/sd devices, they are managing the I/O going through these sd devices.
They are managing it, it terms of load balancing and fault tolerancy.

I hope you get the idea.