I am not sure the drive uses a proprietary filesystem, but more like the disk is split into multiple partitions and then each partition is formatted with a different partition type. For example on my EX4100, I have these partitions on the first drive:
root@WDMyCloudEX4100 /dev # cat /proc/partitions | grep sda
8 0 2930266584 sda
8 1 2097152 sda1
8 2 2926070784 sda2
8 3 1049031 sda3
8 4 1048576 sda4
If I look at the contents of the /proc/mdstat special file:
root@WDMyCloudEX4100 /dev # cat /proc/mdstat
Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
md1 : active raid5 sdc2 sda2 sdb2 sdd2
8778211776 blocks super 1.0 level 5, 64k chunk, algorithm 2 [4/4] [UUUU]
bitmap: 2/2 pages [64KB], 131072KB chunk
md0 : active raid1 sda1 sdb1 sdd1 sdc1
2097088 blocks [4/4] [UUUU]
bitmap: 0/16 pages [0KB], 8KB chunk
unused devices: <none>
This shows that sda1 and sda2 are used for the RAID devices, where md0 is used for swap (look in the “dmesg” output) and md1 is the actual data RAID drive.
If I do a “df”, I can see that sda4 is used for storing configuration data:
root@WDMyCloudEX4100 /dev # df -k /dev/sda4
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda4 951204 1944 932876 0% /mnt/HD_a4
Running the mount command and looking at the “md1” device and the “sda4” device shows the following:
root@WDMyCloudEX4100 /dev # mount | egrep "sda|md1"
/dev/sda4 on /mnt/HD_a4 type ext4 (rw,relatime,data=ordered)
/dev/md1 on /mnt/HD/HD_a2 type ext4
/dev/md1 on /mnt/HD/HD_a2/Nas_Prog/_docker/devicemapper type ext4
So you can see that “ext4” is used. I am unsure of the contents of /dev/sda3 and if I was more inclined I would probably try and mount it and check it out. From the partition table it is a similar size to partition /dev/sda4.
Not sure if this helps!!!