1e18750288
Add more examples and explanations how the filters can be used. Pull-request: #486 Author: Eideen Signed-off-by: David Sterba <dsterba@suse.com>
105 lines
3.8 KiB
ReStructuredText
105 lines
3.8 KiB
ReStructuredText
Adding new device
|
|
^^^^^^^^^^^^^^^^^
|
|
|
|
The unallocated space requirements depend on the selected storage
|
|
profiles. The requirements for the storage profile must be met for the
|
|
selected for both data and metadata (e.g. if you have single data and
|
|
RAID1 metadata, the stricter RAID1 requirements must be met or the
|
|
filesystem may run out of metadata space and go read-only).
|
|
|
|
Before adding a drive, make sure there is enough unallocated space on
|
|
existing drives to create new metadata block groups (for filesystems
|
|
over 50GB, this is `1GB * (number_of_devices + 2))`.
|
|
|
|
If using a striped profile (`raid0`, `raid10`, `raid5`, or `raid6`), then do a
|
|
full data balance of all data after adding a drive. If adding multiple
|
|
drives at once, do a full data balance after adding the last one.
|
|
|
|
.. code-block:: bash
|
|
|
|
btrfs balance start -v --full-balance mnt/
|
|
|
|
If the balance is interrupted, it can be restarted using the *stripes*
|
|
filter (i.e. `-dstripes=1..N` where *N* is the previous size of the array
|
|
before the new device was added) as long as all devices are the same size.
|
|
If the device sizes are different, a specialized userspace balance tool
|
|
is required. The data balance must be completed before adding any new
|
|
devices or increasing the size of existing ones.
|
|
|
|
.. code-block:: bash
|
|
|
|
# For going from 4 disk to 5 disks, in Raid 5
|
|
btrfs balance start -v -dstripes=1..4 mnt/
|
|
|
|
If you are not using a striped profile now, but intend to convert to a
|
|
striped profile in the future, always perform a full data balance after
|
|
adding drives or replacing existing drives with larger ones. The stock
|
|
*btrfs balance* tool cannot cope with special cases on filesystems with
|
|
striped raid profiles, and will paint itself into a corner that will
|
|
require custom userspace balancing tools to recover if you try.
|
|
|
|
To watch one can use the following:
|
|
|
|
.. code-block:: bash
|
|
|
|
watch "btrfs filesystem usage -T mnt/; btrfs balance status mnt/"
|
|
|
|
Convert RAID1 after mkfs with defaults
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
If you forgot to set the block group profile when creating the volume, run the
|
|
following command:
|
|
|
|
.. code-block:: bash
|
|
|
|
btrfs balance start -v convert=raid1,soft mnt/
|
|
|
|
This will convert all remaining profiles that are not yet *raid1*.
|
|
|
|
Convert data to RAID10 with RAID1C4 for metadata
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
If you a have multi device setup, or you'd like to have different profiles on a
|
|
single disk, e.g. *RAID10* for data and *RAID1C4* for metadata and system:
|
|
|
|
.. code-block:: bash
|
|
|
|
btrfs balance start -v -mconvert=raid1C4,soft -dconvert=raid10,soft mnt/
|
|
|
|
Compact under used chunks
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
If the data chunks are not balanced and used only partially, the *usage* filter
|
|
can be used to make them more compact:
|
|
|
|
.. code-block:: bash
|
|
|
|
btrfs balance start -v -dusage=10 mnt/
|
|
|
|
If the percent starts from a small number, like 5 or 10, the chunks will be
|
|
processed relatively quickly and will make more space available. Increasing the
|
|
percentage can then make more chunks compact by relocating the data.
|
|
|
|
Chunks utilized up to 50% can be relocated to other chunks while still freeing
|
|
the space. With utilization higher than 50% the chunks will be basically only
|
|
moved on the devices. The actual chunk layout may help to coalesce the free
|
|
space but this is a secondary effect.
|
|
|
|
.. code-block:: bash
|
|
|
|
for USAGE in {10..50..10} do
|
|
btrfs balance start -v -dusage=$USAGE mnt/
|
|
done
|
|
|
|
Fix incomplete balance
|
|
^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
If the balance is interrupted (due to reboot or cancelled) during conversion to
|
|
RAID1. The following command will skip all RAID1 chunks that have been already
|
|
converted and continue with what's left to convert. Note that an interrupted
|
|
conversion may leave the last chunk under utilized.
|
|
|
|
.. code-block:: bash
|
|
|
|
btrfs balance start convert=raid1,soft mnt/
|