Description
===========
At present, the value of free_capacity for a rbd pool is "max_avail"
retrieved from the command 'ceph df -f json' when quota limit is not
set for this pool. And in that scenario the value of total_capacity
is sum of free_capacity and 'bytes_used' also retrieved from the
command 'ceph df -f json' in the case of dynamic total capacity.
However, there is a considerably difference for the command
'ceph df -f json' for different ceph versions. For example, the output
of that command of the version 12.2.11 of ceph lacks 'STORED' field and
the formula of its '%USED' filed is relevant to 'USED' field while the
output of that command of the version 12.2.13 possesses 'STORED' field
and the formula of its '%USED' filed is relevant to 'STORED' field.
More concrete outputs and formulas are as follows.
root@cmn01:~# ceph --version
ceph version 12.2.11 (26dc3775efc7bb286a1d6d66faee0ba30ea23eee) luminous (stable)
root@cmn01:~# ceph df
GLOBAL:
SIZE AVAIL RAW USED %RAW USED
375TiB 320TiB 54.5TiB 14.54
POOLS:
NAME ID USED %USED MAX AVAIL OBJECTS
cn-a.rgw.meta 1 219KiB 0 68.6TiB 789
cn-a.rgw.buckets.index 2 0B 0 68.6TiB 352
cn-a.rgw.control 3 0B 0 68.6TiB 8
cn-a.rgw.buckets.data 4 312GiB 0.44 68.6TiB 442440
.rgw.root 5 23.3KiB 0 68.6TiB 37
volumes 6 3.99TiB 31.37 8.73TiB 1123150
images 7 6.31TiB 41.47 8.90TiB 828990
vms 8 3.40TiB 24.84 10.3TiB 889292
cn-a.rgw.log 9 197B 0 68.6TiB 316
cn-a.rgw.buckets.non-ec 22 0B 0 68.6TiB 25
volumes_nvme 44 4.25TiB 29.24 10.3TiB 1913190
cn-a.rgw.buckets-ec.data 47 4.30GiB 0 137TiB 1792
%USED of volumes pool：USED/(USED+MAX AVAIL) = 3.99/(3.99+8.73) ≈ 31.37%
root@stor-mgt01:~# ceph --version
ceph version 12.2.13 (584a20eb0237c657dc0567da126be145106aa47e) luminous (stable)
root@stor-mgt01:~# ceph df
RAW STORAGE:
CLASS SIZE AVAIL USED RAW USED %RAW USED
sas 1.6 TiB 1.6 TiB 522 MiB 6.5 GiB 0.39
sata 106 TiB 104 TiB 2.2 TiB 2.2 TiB 2.08
ssd 21 TiB 18 TiB 3.2 TiB 3.2 TiB 15.42
TOTAL 129 TiB 124 TiB 5.4 TiB 5.5 TiB 4.23
POOLS:
POOL ID PGS STORED OBJECTS USED %USED MAX AVAIL
nova.vms 3 64 277 GiB 84.14k 831 GiB 4.97 5.2 TiB
cinder.volumes_ssd 4 1024 254 GiB 76.76k 759 GiB 4.56 5.2 TiB
glance.images 5 256 565 GiB 73.36k 1.7 TiB 9.63 5.2 TiB
cinder.volumes_sas 17 256 0 B 0 0 B 0 529 GiB
cinder.volumes_sata 18 1024 332 GiB 99.07k 1018 GiB 1.00 33 TiB
region-stackdeva.rgw.meta 19 16 5.1 KiB 20 3.0 MiB 0 33 TiB
.rgw.root 20 16 7.7 KiB 19 3.4 MiB 0 33 TiB
region-stackdeva.rgw.control 21 16 0 B 8 0 B 0 33 TiB
region-stackdeva.rgw.log 22 16 399 KiB 214 783 KiB 0 33 TiB
region-stackdeva.rgw.buckets.index 23 16 72 MiB 4 72 MiB 0 33 TiB
region-stackdeva.rgw.buckets.data 24 256 98 GiB 100.53k 294 GiB 0.29 33 TiB
region-stackdeva.rgw.buckets.non-ec 25 16 0 B 0 0 B 0 33 TiB
region-stackdeva.rgw.buckets-ec.data 27 64 0 B 0 0 B 0 66 TiB
rbd 32 64 389 B 1 132 KiB 0 32 TiB
%USED of cinder.volumes_ssd pool：STORED/(STORED+MAX AVAIL) = 254/(254+5.2*1024) ≈ 4.55%
The presently rbd driver calculates the total_capacity by free_capacity plus 'bytes_used' which just corresponds to 'USED' field.
Therefore, is it better to take into accout to 'STORED' field when this field exists?
Fix proposed to branch: master
Review: https:/