Re: Ceph OSD reported Slow operations

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I'm afraid you're simply hitting the I/O limits of your disks.

/Z

On Thu, 2 Nov 2023 at 03:40, V A Prabha <prabhav@xxxxxxx> wrote:

>  Hi Eugen
>  Please find the details below
>
>
> root@meghdootctr1:/var/log/ceph# ceph -s
> cluster:
> id: c59da971-57d1-43bd-b2b7-865d392412a5
> health: HEALTH_WARN
> nodeep-scrub flag(s) set
> 544 pgs not deep-scrubbed in time
>
> services:
> mon: 3 daemons, quorum meghdootctr1,meghdootctr2,meghdootctr3 (age 5d)
> mgr: meghdootctr1(active, since 5d), standbys: meghdootctr2, meghdootctr3
> mds: 3 up:standby
> osd: 36 osds: 36 up (since 34h), 36 in (since 34h)
> flags nodeep-scrub
>
> data:
> pools: 2 pools, 544 pgs
> objects: 10.14M objects, 39 TiB
> usage: 116 TiB used, 63 TiB / 179 TiB avail
> pgs: 544 active+clean
>
> io:
> client: 24 MiB/s rd, 16 MiB/s wr, 2.02k op/s rd, 907 op/s wr
>
>
> Ceph Versions:
>
> root@meghdootctr1:/var/log/ceph# ceph --version
> ceph version 14.2.16 (762032d6f509d5e7ee7dc008d80fe9c87086603c) nautilus
> (stable)
>
> Ceph df -h
> https://pastebin.com/1ffucyJg
>
> Ceph OSD performance dump
> https://pastebin.com/1R6YQksE
>
> Ceph tell osd.XX bench  (Out of 36 osds only 8 OSDs give High IOPS value
> of 250
> +. Out of that 4 OSDs are from HP 3PAR and 4 OSDS from DELL EMC. We are
> using
> only 4 OSDs from HP3 par and it is working fine without any latency and
> iops
> issues from the beginning but the remaining 32 OSDs are from DELL EMC in
> which 4
> OSDs are much better than the remaining 28 OSDs)
>
> https://pastebin.com/CixaQmBi
>
> Please help me to identify if the issue is with the DELL EMC Storage, Ceph
> configuration parameter tuning or the Overload in the cloud setup
>
>
>
> On November 1, 2023 at 9:48 PM Eugen Block <eblock@xxxxxx> wrote:
> > Hi,
> >
> > for starters please add more cluster details like 'ceph status', 'ceph
> > versions', 'ceph osd df tree'. Increasing the to 10G was the right
> > thing to do, you don't get far with 1G with real cluster load. How are
> > the OSDs configured (HDD only, SSD only or HDD with rocksdb on SSD)?
> > How is the disk utilization?
> >
> > Regards,
> > Eugen
> >
> > Zitat von prabhav@xxxxxxx:
> >
> > > In a production setup of 36 OSDs( SAS disks) totalling 180 TB
> > > allocated to a single Ceph Cluster with 3 monitors and 3 managers.
> > > There were 830 volumes and VMs created in Openstack with Ceph as a
> > > backend. On Sep 21, users reported slowness in accessing the VMs.
> > > Analysing the logs lead us to problem with SAS , Network congestion
> > > and Ceph configuration( as all default values were used). We updated
> > > the Network from 1Gbps to 10Gbps for public and cluster networking.
> > > There was no change.
> > > The ceph benchmark performance showed that 28 OSDs out of 36 OSDs
> > > reported very low IOPS of 30 to 50 while the remaining showed 300+
> > > IOPS.
> > > We gradually started reducing the load on the ceph cluster and now
> > > the volumes count is 650. Now the slow operations has gradually
> > > reduced but I am aware that this is not the solution.
> > > Ceph configuration is updated with increasing the
> > > osd_journal_size to 10 GB,
> > > osd_max_backfills = 1
> > > osd_recovery_max_active = 1
> > > osd_recovery_op_priority = 1
> > > bluestore_cache_trim_max_skip_pinned=10000
> > >
> > > After one month, now we faced another issue with Mgr daemon stopped
> > > in all 3 quorums and 16 OSDs went down. From the
> > > ceph-mon,ceph-mgr.log could not get the reason. Please guide me as
> > > its a production setup
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> >
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> Thanks & Regards,
> Ms V A Prabha / श्रीमती प्रभा वी ए
> Joint Director / संयुक्त निदेशक
> Centre for Development of Advanced Computing(C-DAC) / प्रगत संगणन विकास
> केन्द्र(सी-डैक)
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