Unknown filesystems on RAID5 partitions

I am trying to retrieve data from NAS (Acer Altos EasyStore M2) with dead mainboard. System in the NAS is based on CentOS 5 and some software from Falcon (FalconStore) is used.

I removed disks from NAS and connected to other computer. After starting linux from live media (ubuntu) I see all 4 disks and system detected the RAID partitions and reassembled two RAID devices. But I cannot mount any partition from RAID devices.

Partitions on disk /dev/sda (sdb, sdc and sdd are the same):

Disk /dev/sda: 931.53 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: ST1000DM010-2EP1
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0x00000000

Device     Boot   Start        End    Sectors   Size Id Type
/dev/sda1             1    6297479    6297479     3G 83 Linux
/dev/sda2       6297480    7357769    1060290 517.7M 82 Linux swap / Solaris
/dev/sda3       7357770 1953525167 1946167398   928G 89 unknown

Assembled RAID devices:

Disk /dev/md127: 3 GiB, 3224240128 bytes, 6297344 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Alignment offset: 3584 bytes

Disk /dev/md126: 1.83 TiB, 1992875180032 bytes, 3892334336 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 65536 bytes / 131072 bytes
Disklabel type: dos
Disk identifier: 0x00000000

Device       Boot Start        End    Sectors  Size Id Type
/dev/md126p1          1      16064      16064  7.9M 77 unknown
/dev/md126p2      16065 3892334335 3892318271  1.8T 88 Linux plaintext

RAID status from /proc/mdstat:

Personalities : [raid1] [raid6] [raid5] [raid4] [linear] [multipath] [raid0] [raid10] 
md126 : active (auto-read-only) raid5 sdd3[0] sdb3[1] sda3[3](S) sdc3[2]
      1946167168 blocks level 5, 64k chunk, algorithm 2 [3/3] [UUU]
  
md127 : active (auto-read-only) raid1 sdc1[1] sdd1[2] sdb1[0] sda1[3]
      3148672 blocks [4/4] [UUUU]
  
unused devices: <none>

md127 seems like the system disk (all 4 partitions are mirrored).

md126p2 seems like data partition.

I am not sure about md126p1 - 8MB only...

I was looking around and found the firmware here. It contains the image altos_256_flash_2052. Probably this is the content of flash memory on the mainboard. So I wrote the image to the USB disk an tried to boot. It is booting but stuck on prompt:

(none) login:

and I cannot continue without credentials.

Can someone help me to identify the filesystem type and mount it to retrieve data? Probably I need only to read the biggest (2TB) data partition..

EDIT: Adding blkid output (now from CentOS 7)

/dev/sdb1: UUID="75835a1d-dfbd-4673-0890-1856f768949d" TYPE="linux_raid_member" 
/dev/sdb2: TYPE="swap" 
/dev/sdb3: UUID="34c90eaa-f409-f278-d0ac-5b088a21cdc7" TYPE="linux_raid_member" 
/dev/sdc1: UUID="75835a1d-dfbd-4673-0890-1856f768949d" TYPE="linux_raid_member" 
/dev/sdc2: TYPE="swap" 
/dev/sdc3: UUID="34c90eaa-f409-f278-d0ac-5b088a21cdc7" TYPE="linux_raid_member" 
/dev/sdd1: UUID="75835a1d-dfbd-4673-0890-1856f768949d" TYPE="linux_raid_member" 
/dev/sdd2: TYPE="swap" 
/dev/sdd3: UUID="34c90eaa-f409-f278-d0ac-5b088a21cdc7" TYPE="linux_raid_member" 
/dev/sda1: UUID="75835a1d-dfbd-4673-0890-1856f768949d" TYPE="linux_raid_member" 
/dev/sda2: TYPE="swap" 
/dev/sda3: UUID="34c90eaa-f409-f278-d0ac-5b088a21cdc7" TYPE="linux_raid_member" 
/dev/sde1: UUID="dc6f13be-2e3b-4deb-bfb1-a143dbce9de8" TYPE="xfs" 
/dev/sde2: UUID="NWRZRS-509E-KNzF-iFL0-WS8r-KIHV-DSdVUa" TYPE="LVM2_member" 
/dev/mapper/centos-root: UUID="608eab84-0b37-4b9f-86c8-da75b5e03dba" TYPE="xfs" 
/dev/mapper/centos-swap: UUID="5599438f-d0b2-428f-93b1-98349df138c4" TYPE="swap" 
/dev/mapper/centos-home: UUID="62d80f29-37a9-4261-89ed-80c4ec75bcc1" TYPE="xfs" 
/dev/md126: UUID="39310d11-dce7-4bd4-b47d-056d9db24a5e" TYPE="ext3" 
/dev/md127: PTTYPE="dos"

/dev/md126 - succesfuly mounted - as expected it is a system partition 3GB.

Still I cannot mount /dev/md127...

looking into log file grabbed from system partition - seems that special driver is used to work with data partition:

May  3 10:30:07 NAS-SERVER kernel: kfsnbase: module license 'unspecified' taints kernel.
May  3 10:30:07 NAS-SERVER kernel: FSNBASE init_module, got kfsnbase major 252 for char device
May  3 10:30:07 NAS-SERVER kernel: FSNBASE init_module, kfsnbase will use adaptor 'blkscsi'.
May  3 10:30:07 NAS-SERVER kernel: FSNBASE init_module, min_reserved_outcmds is 8192
May  3 10:30:07 NAS-SERVER kernel: FSNBASE init_module, scsi_buf_len is (2097152)
May  3 10:30:07 NAS-SERVER kernel: IOCORE1 ipstor_scsi_done_startup: ipstor_scsi_done_thread running.
May  3 10:30:07 NAS-SERVER kernel: IOCORE1 Special vendor disk detect
May  3 10:30:07 NAS-SERVER kernel: IOCORE1 ====================
May  3 10:30:07 NAS-SERVER kernel: IOCORE1 Special host type type detect

May  3 10:30:07 NAS-SERVER ipstor: Starting IPStor Server (FSNBase) Module succeeded
May  3 10:30:07 NAS-SERVER kernel: IOCORE1 Cisco iSCSI driver
May  3 10:30:07 NAS-SERVER kernel: IOCORE1 iSCSI Initiator over TCP/IP
May  3 10:30:07 NAS-SERVER kernel: IOCORE1 StorwareRAID  driver
May  3 10:30:07 NAS-SERVER kernel: IOCORE1 iscsi_tcp
May  3 10:30:07 NAS-SERVER kernel: IOCORE1 iscsi_iser
May  3 10:30:07 NAS-SERVER kernel: IOCORE1 MPT SPI Host
May  3 10:30:07 NAS-SERVER kernel: IOCORE1 ====================
May  3 10:30:09 NAS-SERVER kernel: scsi98 : FalconStor BLOCK-SCSI driver v6.00 Build 6086
May  3 10:30:09 NAS-SERVER kernel:   Vendor: FALCON    Model: LVMDISK-M09N01    Rev: v1.0
May  3 10:30:09 NAS-SERVER kernel:   Type:   Direct-Access                      ANSI SCSI revision: 02
May  3 10:30:09 NAS-SERVER kernel: blk_queue_segment_boundary: set to minimum fff
May  3 10:30:09 NAS-SERVER kernel: SCSI device sdf: 3892334336 512-byte hdwr sectors (1992875 MB)
May  3 10:30:09 NAS-SERVER kernel: sdf: Write Protect is off
May  3 10:30:09 NAS-SERVER kernel: SCSI device sdf: drive cache: write through w/ FUA
May  3 10:30:09 NAS-SERVER kernel: SCSI device sdf: 3892334336 512-byte hdwr sectors (1992875 MB)
May  3 10:30:09 NAS-SERVER kernel: sdf: Write Protect is off

So I need to boot compatible kernel and load kfsnbase module, maybe more...