Hi, A flash system needs free space to work efficiently. Hence my hypothesis that fully allocated disks need to be notified of free blocks (trim) ________________________________________________________ Cordialement, *David CASIER* ________________________________________________________ Le lun. 4 déc. 2023 à 06:01, Szabo, Istvan (Agoda) <Istvan.Szabo@agoda.com> a écrit :
With the nodes that has some free space on that namespace, we don't have issue, only with this which is weird. ------------------------------ *From:* Anthony D'Atri <anthony.datri@gmail.com> *Sent:* Friday, December 1, 2023 10:53 PM *To:* David C. <david.casier@aevoo.fr> *Cc:* Szabo, Istvan (Agoda) <Istvan.Szabo@agoda.com>; Ceph Users < ceph-users@ceph.io> *Subject:* Re: [ceph-users] How to identify the index pool real usage?
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Today we had a big issue with slow ops on the nvme drives which holding the index pool.
Why the nvme shows full if on ceph is barely utilized? Which one I
should
belive?
When I check the ceph osd df it shows 10% usage of the osds (1x 2TB nvme drive has 4x osds on it):
Why split each device into 4 very small OSDs? You're losing a lot of capacity to overhead.
ID CLASS WEIGHT REWEIGHT SIZE RAW USE DATA OMAP
META AVAIL %USE VAR PGS STATUS
195 nvme 0.43660 1.00000 447 GiB 47 GiB 161 MiB 46 GiB 656 MiB 400 GiB 10.47 0.21 64 up 252 nvme 0.43660 1.00000 447 GiB 46 GiB 161 MiB 45 GiB 845 MiB 401 GiB 10.35 0.21 64 up 253 nvme 0.43660 1.00000 447 GiB 46 GiB 229 MiB 45 GiB 662 MiB 401 GiB 10.26 0.21 66 up 254 nvme 0.43660 1.00000 447 GiB 46 GiB 161 MiB 44 GiB 1.3 GiB 401 GiB 10.26 0.21 65 up 255 nvme 0.43660 1.00000 447 GiB 47 GiB 161 MiB 46 GiB 1.2 GiB 400 GiB 10.58 0.21 64 up 288 nvme 0.43660 1.00000 447 GiB 46 GiB 161 MiB 44 GiB 1.2 GiB 401 GiB 10.25 0.21 64 up 289 nvme 0.43660 1.00000 447 GiB 46 GiB 161 MiB 45 GiB 641 MiB 401 GiB 10.33 0.21 64 up 290 nvme 0.43660 1.00000 447 GiB 45 GiB 229 MiB 44 GiB 668 MiB 402 GiB 10.14 0.21 65 up
However in nvme list it says full: Node SN Model Namespace Usage Format FW Rev ---------------- --------------------
-------------------------- ---------------- --------
/dev/nvme0n1 90D0A00XTXTR KCD6XLUL1T92 1 1.92 TB / 1.92 TB 512 B + 0 B GPK6 /dev/nvme1n1 60P0A003TXTR KCD6XLUL1T92 1 1.92 TB / 1.92 TB 512 B + 0 B GPK6
That command isn't telling you what you think it is. It has no awareness of actual data, it's looking at NVMe namespaces.
With some other node the test was like:
* if none of the disk full, no slow ops. * If 1x disk full and the other not, has slow ops but not too much * if none of the disk full, no slow ops.
The full disks are very highly utilized during recovery and they are holding back the operations from the other nvmes.
What's the reason that even if the pgs are the same in the cluster +/-1 regarding space they are not equally utilized.
Thank you
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