MSA500 controller logical status message keep appear

[wan khairul]

i have msa500 controller with 5 36gb raid5 and 2 logical drive..the problem is logical 1 message keep appear "Background parity initialization is currently queued or in progress on logical drive 1 ( RAID 5 in array A). If background parity initialization is queued, it will start when I/O is performed on the drive. When background parity initialization completes, the performance of the logical drive will improve. "

and the light hd indicator 1 scsi hd from 5 keep blinking.
why?tq