Cannot correctly install either with automatic or manual partitioning

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Brief description of the problem

Hi guys!

Total noob here with a problem installing.
If the Automatic partition scheme is selected during the install phase, the disk is partitioned using LVM.
When attempting to set the partitions scheme manually, I can select btrfs, but I couldn’t find a mount point that would actually cause the system to then boot normally.
Can someone provide the actual detailed settings for a manual partition scheme that works? I could not find a guide detailing that part.
The software is to be installed on a HP thin client on a 16GB flash module.
Gotta say, the first impression is not great, as it appears to be a bit of a hassle to even get the thing to work.
Also, I have a couple of drives in an external enclosure which are formatted ext4 and NTFS (previously used on OMV) and which I do not want to format again.
It is not clear exactly whether they will work as is, or I have to wipe and re-format them, as this would be a deal breaker.

Thanks in advance for the help and sorry for my first post being a “need help” post.
Gotta say, I love the interface and options

Detailed step by step instructions to reproduce the problem

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Web-UI screenshot

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Error Traceback provided on the Web-UI

Traceback (most recent call last): File "/opt/rockstor/src/rockstor/rest_framework_custom/", line 41, in _handle_exception yield File "/opt/rockstor/src/rockstor/storageadmin/views/", line 377, in post return self._update_disk_state() File "/opt/rockstor/eggs/Django-1.8.16-py2.7.egg/django/utils/", line 145, in inner return func(*args, **kwargs) File "/opt/rockstor/src/rockstor/storageadmin/views/", line 75, in _update_disk_state disks = scan_disks(settings.MIN_DISK_SIZE) File "/opt/rockstor/src/rockstor/system/", line 131, in scan_disks base_root_disk = root_disk() File "/opt/rockstor/src/rockstor/system/", line 908, in root_disk raise NonBTRFSRootException(msg) NonBTRFSRootException: 'root filesystem is not BTRFS. During Rockstor installation, you must select BTRFS instead of LVM and other options for root filesystem. Please re-install Rockstor properly.'