Hugo Mills - 15.10.18, 16:26: > On Mon, Oct 15, 2018 at 05:24:08PM +0300, Anton Shepelev wrote: > > Hello, all > > > > While trying to resolve free space problems, and found that > > > > I cannot interpret the output of: > > > btrfs filesystem show > > > > Label: none uuid: 8971ce5b-71d9-4e46-ab25-ca37485784c8 > > Total devices 1 FS bytes used 34.06GiB > > devid 1 size 40.00GiB used 37.82GiB path /dev/sda2 > > > > How come the total used value is less than the value listed > > for the only device? > > "Used" on the device is the mount of space allocated. "Used" on the > FS is the total amount of actual data and metadata in that > allocation. > > You will also need to look at the output of "btrfs fi df" to see > the breakdown of the 37.82 GiB into data, metadata and currently > unused.
I usually use btrfs fi usage -T, cause 1. It has all the information. 2. It differentiates between used and allocated. % btrfs fi usage -T / Overall: Device size: 100.00GiB Device allocated: 54.06GiB Device unallocated: 45.94GiB Device missing: 0.00B Used: 46.24GiB Free (estimated): 25.58GiB (min: 25.58GiB) Data ratio: 2.00 Metadata ratio: 2.00 Global reserve: 70.91MiB (used: 0.00B) Data Metadata System Id Path RAID1 RAID1 RAID1 Unallocated -- ------------------------ -------- --------- -------- ----------- 2 /dev/mapper/msata-debian 25.00GiB 2.00GiB 32.00MiB 22.97GiB 1 /dev/mapper/sata-debian 25.00GiB 2.00GiB 32.00MiB 22.97GiB -- ------------------------ -------- --------- -------- ----------- Total 25.00GiB 2.00GiB 32.00MiB 45.94GiB Used 22.38GiB 754.66MiB 16.00KiB For RAID it in some place reports the raw size and sometimes the logical size. Especially in the "Total" line I find this a bit inconsistent. "RAID1" columns show logical size, "Unallocated" shows raw size. Also "Used:" in the global section shows raw size and "Free (estimated):" shows logical size. Thanks -- Martin