Hi Seena, this parameter isn't intended to be adjusted in production environments - it's supposed that default behavior covers all regular customers' needs. The issue though is that default setting is invalid. It should be 'use_some_extra'. Gonna fix that shortly... Thanks, Igor On 8/20/2020 1:44 PM, Seena Fallah wrote:
Hi Igor.
Could you please tell why this config is in LEVEL_DEV (https://github.com/ceph/ceph/pull/29687/files#diff-3d7a065928b2852c228ffe669... As it is documented in Ceph we can't use LEVEL_DEV in production environments!
Thanks
On Thu, Aug 20, 2020 at 1:58 PM Igor Fedotov <ifedotov@suse.de <mailto:ifedotov@suse.de>> wrote:
Hi Simon,
starting Nautlus v14.2.10 Bluestore is able to use 'wasted' space at DB volume.
see this PR: https://github.com/ceph/ceph/pull/29687
Nice overview on the overall BlueFS/RocksDB design can be find here:
https://cf2.cloudferro.com:8080/swift/v1/AUTH_5e376cddf8a94f9294259b5f48d7b2...
Which also includes some overview (as well as additional concerns) for changes brought by the above-mentioned PR.
Thanks,
Igor
On 8/20/2020 11:39 AM, Simon Oosthoek wrote: > Hi Michael, > > thanks for the explanation! So if I understand correctly, we waste 93 > GB per OSD on unused NVME space, because only 30GB is actually used...? > > And to improve the space for rocksdb, we need to plan for 300GB per > rocksdb partition in order to benefit from this advantage.... > > Reducing the number of small files is something we always ask of our > users, but reality is what it is ;-) > > I'll have to look into how I can get an informative view on these > metrics... It's pretty overwhelming the amount of information coming > out of the ceph cluster, even when you look only superficially... > > Cheers, > > /Simon > > On 20/08/2020 10:16, Michael Bisig wrote: >> Hi Simon >> >> As far as I know, RocksDB only uses "leveled" space on the NVME >> partition. The values are set to be 300MB, 3GB, 30GB and 300GB. Every >> DB space above such a limit will automatically end up on slow devices. >> In your setup where you have 123GB per OSD that means you only use >> 30GB of fast device. The DB which spills over this limit will be >> offloaded to the HDD and accordingly, it slows down requests and >> compactions. >> >> You can proof what your OSD currently consumes with: >> ceph daemon osd.X perf dump >> >> Informative values are `db_total_bytes`, `db_used_bytes` and >> `slow_used_bytes`. This changes regularly because of the ongoing >> compactions but Prometheus mgr module exports these values such that >> you can track it. >> >> Small files generally leads to bigger RocksDB, especially when you >> use EC, but this depends on the actual amount and file sizes. >> >> I hope this helps. >> Regards, >> Michael >> >> On 20.08.20, 09:10, "Simon Oosthoek" <s.oosthoek@science.ru.nl <mailto:s.oosthoek@science.ru.nl>> wrote: >> >> Hi >> >> Recently our ceph cluster (nautilus) is experiencing bluefs >> spillovers, >> just 2 osd's and I disabled the warning for these osds. >> (ceph config set osd.125 bluestore_warn_on_bluefs_spillover false) >> >> I'm wondering what causes this and how this can be prevented. >> >> As I understand it the rocksdb for the OSD needs to store more >> than fits >> on the NVME logical volume (123G for 12T OSD). A way to fix it >> could be >> to increase the logical volume on the nvme (if there was space >> on the >> nvme, which there isn't at the moment). >> >> This is the current size of the cluster and how much is free: >> >> [root@cephmon1 ~]# ceph df >> RAW STORAGE: >> CLASS SIZE AVAIL USED RAW USED >> %RAW USED >> hdd 1.8 PiB 842 TiB 974 TiB 974 >> TiB 53.63 >> TOTAL 1.8 PiB 842 TiB 974 TiB 974 >> TiB 53.63 >> >> POOLS: >> POOL ID STORED OBJECTS USED >> %USED MAX AVAIL >> cephfs_data 1 572 MiB 121.26M 2.4 GiB >> 0 167 TiB >> cephfs_metadata 2 56 GiB 5.15M 57 GiB >> 0 167 TiB >> cephfs_data_3copy 8 201 GiB 51.68k 602 GiB >> 0.09 222 TiB >> cephfs_data_ec83 13 643 TiB 279.75M 953 TiB >> 58.86 485 TiB >> rbd 14 21 GiB 5.66k 64 GiB >> 0 222 TiB >> .rgw.root 15 1.2 KiB 4 1 MiB >> 0 167 TiB >> default.rgw.control 16 0 B 8 0 B >> 0 167 TiB >> default.rgw.meta 17 765 B 4 1 MiB >> 0 167 TiB >> default.rgw.log 18 0 B 207 0 B >> 0 167 TiB >> cephfs_data_ec57 20 433 MiB 230 1.2 GiB >> 0 278 TiB >> >> The amount used can still grow a bit before we need to add >> nodes, but >> apparently we are running into the limits of our rocskdb >> partitions. >> >> Did we choose a parameter (e.g. minimal object size) too small, >> so we >> have too much objects on these spillover OSDs? Or is it that too >> many >> small files are stored on the cephfs filesystems? >> >> When we expand the cluster, we can choose larger nvme devices to >> allow >> larger rocksdb partitions, but is that the right way to deal >> with this, >> or should we adjust some parameters on the cluster that will >> reduce the >> rocksdb size? >> >> Cheers >> >> /Simon >> _______________________________________________ >> ceph-users mailing list -- ceph-users@ceph.io <mailto:ceph-users@ceph.io> >> To unsubscribe send an email to ceph-users-leave@ceph.io <mailto:ceph-users-leave@ceph.io> >> > _______________________________________________ > ceph-users mailing list -- ceph-users@ceph.io <mailto:ceph-users@ceph.io> > To unsubscribe send an email to ceph-users-leave@ceph.io <mailto:ceph-users-leave@ceph.io> _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io <mailto:ceph-users@ceph.io> To unsubscribe send an email to ceph-users-leave@ceph.io <mailto:ceph-users-leave@ceph.io>