Getting errors on drives

Hello All,

I am getting below error in var/adm/messages for a drive. Kindly suggest:

acsd[3617]: [ID 600385 daemon.error] Fatal open error on OC9840B_a1p03d01 (device 12, /devices/pci@82,2000/fibre-channel@1/fp@0,0/sg@w500104f00070cf7e,0:raw), errno = 19 (No such device), DOWN'ing it

Netbackup version:6.5.6