[ubuntu] RAIDraid1 readonly (/dev/md126_raid1) and operation not permitted to wirte on disk

I have x3100 M5 v3 server with 1 TB HDDs (2 Nos). I configured RAID 1 in BIOS and fast initialization. showing 1 TB array READONLY (/dev/md126_raid1) and started installation. It showing RAIDraid1 readonly at the time of partitions creation. getting Error Operation not permitted to write on disk.

I tried in different ways. Through Desktop 64bit CD :
Before BIOS RAID 1 config :
created MSDOS New partition table on 2 HDDs. After BIOS RAID 1 creation, repeat the same problem.

After BIOS RAID 1 Config :- created MSDOS New partition table on 2 HDDs. But the exising BIOS RAID 1 config lost.

Please help how to fix this problem a