Hi Kilian,
we do not currently use this mode of ceph clustering. but normally you
need to assign the crush rule to the pool as well, otherwise it will
take rule 0 as default.
the following calculation for rule 0 would also work approximately:
(3 Nodes *6 x SSD *1,8TB)/4 = 8,1 TB
hope it helps, Joachim
___________________________________
Clyso GmbH - Ceph Foundation Member
Am 22.06.22 um 18:09 schrieb Kilian Ries:
Hi,
i'm running a ceph stretch cluster with two datacenters. Each of the datacenters has 3x OSD nodes (in total 6x) and 2x monitors. A third monitor is deployed as arbiter node in a third datacenter.
Each OSD node has 6x SSDs with 1,8 TB storage - that gives me a total of about 63 TB storage (6x nodes * 6x SSD * 1,8TB = 63TB)c.
In stretch mode my pool is configured with replication 4x - and as far as i unterstand this should give me a max pool storage size of ~15TB (63TB / 4 = 15,75TB. But if i run "ceph df" it shows me only the half, about ~7,5TB.
$ ceph df
--- RAW STORAGE ---
CLASS SIZE AVAIL USED RAW USED %RAW USED
ssd 63 TiB 63 TiB 35 GiB 35 GiB 0.05
TOTAL 63 TiB 63 TiB 35 GiB 35 GiB 0.05
--- POOLS ---
POOL ID PGS STORED OBJECTS USED %USED MAX AVAIL
device_health_metrics 1 4 4.4 MiB 36 17 MiB 0 7.5 TiB
vm_stretch 2 64 8.2 GiB 2.19k 33 GiB 0.11 7.5 TiB
My replication rule is from the ceph documentation:
https://docs.ceph.com/en/latest/rados/operations/stretch-mode/
rule stretch_rule {
id 1
min_size 1
max_size 10
type replicated
step take site1
step chooseleaf firstn 2 type host
step emit
step take site2
step chooseleaf firstn 2 type host
step emit
}
Any idea why ceph shows me only about half the size i should be able to use (with 4x replicaton on the pool) ?
Thanks,
Regards
Kilian
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