Volume not on preferred path due to AVT/RDAC failover

Hi All,

I Have redisturbute the Volume back to the preferred controller. After about 1 hour, The volume is swing from Controller A to Controller B.

After the volume is swing to Controller B, From the server side, We are unable to see the luns as well.

In another word, once the Volume swing from Preferred controller ( Controller A ) to Controller B without know the reason.

From server side, We are unable to see the Luns.

Kindly Assist in check what causing the Volume swing from Preferred controller ( Controller A ) to Controller B?

And why once the volume swing to controller B, Server unable to see the luns any more?