Hello,
SCSI reservation conflicts happen when there is a mismatch in Host LUN ID values of a LUN which has been zoned across multiple storage groups.
Lets say we have a LUN device with ALU 100 (ALU - Array LUN ID, HLU - Host LUN ID) and we have 2 Storage groups SG1 and SG2, with different ESX hosts in each Storage groups (Note: you can have an ESX host in only one storage group, but you can have a LUN in multiple storage groups). If in SG1, you have added this LUN with HLU 100, and in SG2, you have added this LUN with HLU 200, this is a mismatch in HLU for the LUN with ALU 100 and this can cause SCSI reservation conflicts in all the hosts and the array, since the storage processor will receive SCSI commands for the same LUN with different HLU.
In order to correct this, you have to correct the HLU ID of the LUN in either of the SG, change it to either 100 or 200. For this you have to remove the LUN from the SG, and added it back with the correct HLU. This will fix the SCSI reservation conflicts errors. Detailed in EMC Article - 41822
Thanks,
Thor