Data on btrfs disappeared

I have installed OSMC on my RasPI 2. Then via fstab mounted two flash disks (formatted to btrfs). There was 60GB of data, but now there is no data at all. If I plug it into my computer it is blank as well. Does OSMC make automatic format or so?
Before recovering I need to know what happend, so I can decide what to do.

Were they connected during install or did you connect them later ?

If they were connected during install did you choose a USB install or an SD install ?

During a USB install an attached USB drive will be formatted, but it will not be formatted if you choose an SD install or if you connect the drives later after installation is complete.

Thanks for reply.
They were not. I installed it on SD card on my PC (I chose install on SD). Then I booted OSMC, did some changes. Rebooted and then plugged my USB flash disks, rewrote fstab and then reboot again. After that data disappeared.

Possibly an error in your fstab file, (such as specifying the wrong file system type) but impossible to know really after the fact.

We certainly don’t deliberately delete anything from externally mounted disks.

BTW was there some reason you needed to use fstab to mount your external disks ? OSMC has an automounter (using udisks / udisks-glue) that mounts all detected external drives under /media - 9 times out of 10 this auto mounting should be sufficient, there’s only a few specific cases where it might be useful or necessary to mount an external drive using fstab.

One other thought - did you ever see the contents of your disks on OSMC ? I’m not sure if we have btrfs support in the kernel in OSMC.

cc @sam_nazarko

I have thought OSMC makes some sort of format. In such case I have probably performed some action which deleted it, but it seems really strange to me.
My fstab:

/dev/disk/by-id/usb-PRETEC_32GB_13052410440805848869-0:0-part1 /home/osmc/filmovnicek btrfs defaults 0 0

I just copied it from Raspbian where it worked.
The reason was that I mounted it on another place then media and then shared it via Samba.
I have never seen my content, it was the reason why I firstly though about the formating.
Anyway, thanks for replying.

We have btrfs support