[ceph-users] Raw space usage in Ceph with Bluestore
ifedotov at suse.de
Wed Nov 28 14:05:44 PST 2018
yes, this is a known issue.
Indeed, currently 'ceph df detail' reports raw space usage in GLOBAL
section and 'logical' in the POOLS one. While logical one has some flaws.
There is a pending PR targeted to Nautilus to fix that:
If you want to do an analysis at exactly per-pool level this PR is the
only mean AFAIK.
If per-cluster stats are fine then you can also inspect corresponding
OSD performance counters and sum over all OSDs to get per-cluster info.
This is the most precise but quite inconvenient method for low-level
per-osd space analysis.
"bluestore_allocated": 655360, # space allocated at BlueStore
for the specific OSD
"bluestore_stored": 34768, # amount of data stored at
BlueStore for the specific OSD
Please note, that aggregate numbers built from these parameters include
all the replication/EC overhead. And bluestore_stored vs.
bluestore_allocated difference is due to allocation overhead and/or
On 11/29/2018 12:27 AM, Glider, Jody wrote:
> I’m trying to find a way to determine real/physical/raw storage
> capacity usage when storing a similar set of objects in different
> pools, for example a 3-way replicated pool vs. a 4+2 erasure coded
> pool, and in particular how this ratio changes from small (where
> Bluestore block size matters more) to large object sizes.
> I find that /ceph df detail/ and /rados df/ don’t report on really-raw
> storage, I guess because they’re perceiving ‘raw’ storage from their
> perspective only. If I write a set of objects to each pool, rados df
> shows the space used as the summation of the logical size of the
> objects, while ceph df detail shows the raw used storage as the object
> size * the redundancy factor (e.g. 3 for 3-way replication and 1.5 for
> 4+2 erasure code).
> Any suggestions?
> Jody Glider, Principal Storage Architect
> Cloud Architecture and Engineering, SAP Labs LLC
> 3412 Hillview Ave (PAL 02 23.357), Palo Alto, CA 94304
> E j.glider at sap.com <mailto:j.glider at sap.com>, T +1 650-320-3306, M
> +1 650-441-0241
> ceph-users mailing list
> ceph-users at lists.ceph.com
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