I have recently moved from a 2TB HDD with Windows 7 Enterprise (R) and several ext4 and XFS data partitions to a 4TB HDD by dd 'ing Windows to the new HDD.

When I wanted to create an extended partition over the left 3.5 TB the partitioner told me that I cannpt do that because MSDOS partition tables do not support such big partitions, so I created an 2TB btrfs partition (with several subvolumes for my data) and a 1.5TB extended partition.

Now I have an 900GB btrfs partition and a 2TB btrfs partition, how can I "join" the disk space. I thought that this would be possible using btrfs device add, however this seems to use RAID0, so I would essentialy loose some disk space, because 2*900GB = 1.8TB, while I already have 2TB.

Is there a way to add the second disk, so that I get 2.9TB disk space?

My Disk Setup

1 Answer 1


Your BTRFS defaulted to the raid0 mode when adding a new device; you can change it to single mode by running btrfs balance start -dconvert=single,soft /mountpoint.


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