Any way to make an hex dump of a SAS drive behind a RAID1 (PERC H200) controller?

I have SAS drives in RAID1. The RAID1 is done by a PERC H200 card on a Dell PowerEdge T310. This card has four sockets: 0,1,2,3. The RAID1 uses slots 0 and 1.

When inserting third disk in slot 2, the system goes on working, but the disks in slots 0 and 1 become very busy (sizzling). The disks in slot 0 and 1 are 4TB spinning at 7200 rpm, whilst the disk in slot 2 is a 600GB one at 15000 rpm.

I want to check what is happening, and make sure that RAID1 is not extended to the third disk. I also want to check that the RAID1 is correctly working for disks 0 and 1. For these reasons, I would like to dump the first track of each disk behind the RAID1 card.

The virtual disk in RAID 1 is dev/sda. The physical disks are dev/sg1, dev/sg2.

Smartmontools succeeds passing through the RAID (PERC H200) card to see the disks individually: sudo smartctl -a /dev/sg1 (respectively sg2, sg3)

But I could not dump the first sectors of each disk:

sudo dd if=/dev/sg1 of='dump_of_1st_disk.bin' bs=512 count=63

or

sudo dd if=/dev/sg1 bs=512 count=63 ¦ hexdump -C

Is the SAS controller preventing that or is something wrong with the syntax of the commands?

Is there any way to access the hexadecimal content of the drives behind the card?