What does Btrfs device delete missing mean in raid XX?

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.

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.

When does Btrfs need to be mounted in degraded mode?

But, if a device is missing or the super block has been corrupted, the filesystem will need to be mounted in degraded mode: 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.

Can you add a second disc to a Btrfs disk?

If you did not change this then likely you will have no problem adding the second disc and running re-balance. because only the metadata will be copied to both discs (you can see your metadata size with btrfs filesystem df / ). Just be aware that if either of your disks fails you loose data.

How is a non-RAID filesystem converted to a raid?

A non-RAID filesystem is converted to RAID by adding a device and running a balance filter that will change the chunk allocation profile. For example, to convert an existing single device system ( /dev/sdb1) into a 2 device RAID 1 (to protect against a single disk failure):

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 many devices do I need for Btrfs to work?

For a RAID 6, the minimum is 4 devices. mkfs.btrfs will accept more than one device on the command line. It has options to control the RAID configuration for data ( -d) and metadata ( -m ).

How is Btrfs used to remove devices online?

If data is not converted it does not have any redundant copies at all. btrfs device delete is used to remove devices online. It redistributes any extents in use on the device being removed to the other devices in the filesystem. Example:

Can a single device be used as a Btrfs Mount?

(See btrfs-space-calculator or btrfs disk usage calculator) Non-striped equivalents may give you a more effective use of space (single instead of RAID 0, RAID 1 instead of RAID 10). Once you create a multi-device filesystem, you can use any device in the FS for the mount command:

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.

Which is an example of using btrfs with multiple devices?

The btrfs balance operation will take some time. It reads in all of the FS data and metadata and rewrites it across all the available devices. Depending on the usage scenario that is not needed, one example would be adding a new device to a RAID 1 filesystem whose existing devices still have enough space left.

Is it possible to balance Btrfs across all devices?

The filesystem can be balanced to spread the extents across all the devices. The btrfs balance operation will take some time. It reads in all of the FS data and metadata and rewrites it across all the available devices.