How does btrfs convert data from one raid to another?

How does btrfs convert data from one raid to another?

Running btrfs fi usage /mountpoint will provide more detail. You can convert an existing filesystem to a different RAID level by passing arguments to the balance command. A balance writes all data to the filesystem again, and adding arguments will cause the data to be converted as it is rewritten.

Can A Btrfs be used on more than one device?

If only one device is present, metadata will be duplicated on that one device. For HDD mkfs.btrfs -m dup -d single, for SSD (or non-rotational device) mkfs.btrfs -m single -d single . Btrfs can add and remove devices online, and freely convert between RAID levels after the FS has been created.

How can I convert my filesystem to RAID1?

You can convert an existing filesystem to a different RAID level by passing arguments to the balance command. btrfs balance start -dconvert=raid1 -mconvert=raid1 /mountpoint. A balance writes all data to the filesystem again, and adding arguments will cause the data to be converted as it is rewritten.

What does Btrfs device delete missing mean in raid XX?

btrfs device delete missing tells btrfs to remove the first device that is described by the filesystem metadata but not present when the FS was mounted. In case of RAID XX layout, you cannot go below the minimum number of the device required. So before removing a device (even the missing one) you may need to add a new one.

Can a DF command take into account raid settings?

Utilities such as the regular df command or btrfs fi show do not take RAID settings into account, as that is done by btrfs itself. These tools only show the total amount allocated by btrfs on the disks, they don’t know what format btrfs is using for the data.

Is there a way to increase the metadata in Btrfs?

TL;DR The metadata (if the btrfs is not suffering general low space condition) will automatically increase. In cases that no unallocated free space exists, the automatic increase is hembered. If, however, the data part of btrfs has been allocated more space than it needs, then it is possible to redistribute this.

How big is a multi-device Btrfs file server?

It depends on what profile you use for the data blocks of the multi-device Btrfs filesystem. When you use RAID0 (the default for data blocks), each disks can only be filled up to the capacity of the smallest disk in the array. I have a file server with a 2TB and a 3TB disk. It boots Ubuntu 12.10 from a USB flash drive.

Is it possible to combine different drives in Btrfs?

It is possible to combine drives with different size in btrfs. But currently btrfs does not handel ENOSPC (No space left on device) very well. E.g.