Hi,
You have 67 TB of raw space available. With a replication factor of 3,
which is what you seem to be using, that is ~22 TB usable space under ideal
conditions.
MAX AVAIL column shows the available space, taking into account the raw
space, the replication factor and the CRUSH map, before the first OSD
becomes full. In other words, because of the way the data is distributed
across the OSDs in your cluster, you won't be able to utilize the whole 22
TB because one or more OSDs will get full if you write another 16 TB of
data to your pools.
/Z
On Sun, 28 Jan 2024 at 18:36, V A Prabha <prabhav(a)cdac.in> wrote:
Hi
Just a continuation of this mail, Could you help me out to understand the
ceph df output. PFA the screenshot with this mail.
1. Raw storage is 180 TB
2. Stored Value is 37 TB
3. Used Value is 112 TB
4. Available Value is 67 TB
5. Pool Max Available Value is 16 TB
Though the Available Value is still 67 TB how can it be utilized for the
pools?
On November 6, 2023 at 4:18 PM V A Prabha <prabhav(a)cdac.in> wrote:
Please clarify my query.
I had 700+ volumes (220 applications) running in 36 OSDs when it reported
the slow operations. Due to emergency, we migrated 200+ VMs to another
virtualization environment. So we have shutdown all the related VMs in our
Openstack production setup running with Ceph.
We have not deleted the 200+ volumes from Ceph as waiting for the
concurrence from the departments.
My query is that even when the applications are down, does the volume at
the backend make our cluster busy when there is no active transactions?
Is there any parameter in the ceph osd log and ceph mon log that gives me
the clue for the cluster business?
Is there any zombie or unwanted process that make the ceph cluster busy or
the IOPS budget of the disk that makes the cluster busy?
On November 4, 2023 at 4:29 PM Zakhar Kirpichenko <zakhar(a)gmail.com>
wrote:
You have an IOPS budget, i.e. how much I/O your spinners can deliver.
Space utilization doesn't affect it much.
You can try disabling write (not read!) cache on your HDDs with sdparm
(for example, sdparm -c WCE /dev/bla); in my experience this allows HDDs to
deliver 50-100% more write IOPS. If there is lots of free RAM on the OSD
nodes, you can play with osd_memory_target and bluestore_cache_size_hdd OSD
options; be careful though: depending on you workload, the performance
impact may be insignificant, but your OSDs may run out of memory.
/z
On Sat, 4 Nov 2023 at 12:04, V A Prabha < prabhav(a)cdac.in> wrote:
Now in this situation how can stabilize my production setup as you have
mentioned the cluster is very busy.
Is there any configuration parameter tuning will help or the only option
is to reduce the applications running on the cluster.
Though if I have free available storage of 1.6 TB free in each of my OSD,
that will not help in my IOPS issue right?
Please guide me
On November 2, 2023 at 12:47 PM Zakhar Kirpichenko < zakhar(a)gmail.com>
wrote:
1. The calculated IOPS is for the rw operation
right ?
Total drive IOPS, read or write. Depending on the exact drive models, it
may be lower or higher than 200. I took the average for a smaller sized
7.2k rpm SAS drive. Modern drives usually deliver lower read IOPS and
higher write IOPS.
2. Cluster is very busy? Is there any
misconfiguration or missing tuning
paramater that makes the cluster busy?
You have almost 3k IOPS and your OSDs report slow ops. I'd say the cluster
is busy, as in loaded with I/O, perhaps more I/O than it can handle well.
3. Nodes are not balanced? you mean to say that
the count of OSDs in
each server differs. But we have enabled autoscale and optimal
distribution
so that you can see from the output of ceph osd df tree that is count of
pgs(45/OSD) and use% (65 to 67%). Is that not significant?
Yes, the OSD count differs. This means that the CPU, memory usage, network
load and latency differ per node and may cause performance variations,
depending on your workload.
/Z
On Thu, 2 Nov 2023 at 08:18, V A Prabha < prabhav(a)cdac.in> wrote:
Thanks for your prompt reply ..
But the query is
1.The calculated IOPS is for the rw operation right ?
2. Cluster is very busy? Is there any misconfiguration or missing tuning
paramater that makes the cluster busy?
3. Nodes are not balanced? you mean to say that the count of OSDs in each
server differs. But we have enabled autoscale and optimal distribution so
that you can see from the output of ceph osd df tree that is count of
pgs(45/OSD) and use% (65 to 67%). Is that not significant?
Correct me if my queries are irrelevant
On November 2, 2023 at 11:36 AM Zakhar Kirpichenko < zakhar(a)gmail.com>
wrote:
Sure, it's 36 OSDs at 200 IOPS each (tops, likely lower), I assume size=3
replication so 1/3 of the total performance, and some 30%-ish OSD
overhead.
(36 x 200) * 1/3 * 0.7 = 1680. That's how many IOPS you can realistically
expect from your cluster. You get more than that, but the cluster is very
busy and OSDs aren't coping.
Also your nodes are not balanced.
/Z
On Thu, 2 Nov 2023 at 07:33, V A Prabha < prabhav(a)cdac.in> wrote:
Can you please elaborate your identifications and the statement .
On November 2, 2023 at 9:40 AM Zakhar Kirpichenko < zakhar(a)gmail.com>
wrote:
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(a)cdac.in> 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(a)nde.ag> 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(a)cdac.in:
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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Joint Director / संयुक्त निदेशक
Centre for Development of Advanced Computing(C-DAC) / प्रगत संगणन विकास
केन्द्र(सी-डैक)
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Joint Director / संयुक्त निदेशक
Centre for Development of Advanced Computing(C-DAC) / प्रगत संगणन विकास
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No.4, Rajiv Gandhi Salai / नं.4, राजीव गांधी सलाई
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Centre for Development of Advanced Computing(C-DAC) / प्रगत संगणन विकास
केन्द्र(सी-डैक)
Tidel Park”, 8th Floor, “D” Block, (North &South) / “टाइडल पार्क”,8वीं
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No.4, Rajiv Gandhi Salai / नं.4, राजीव गांधी सलाई
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Joint Director / संयुक्त निदेशक
Centre for Development of Advanced Computing(C-DAC) / प्रगत संगणन विकास
केन्द्र(सी-डैक)
Tidel Park”, 8th Floor, “D” Block, (North &South) / “टाइडल पार्क”,8वीं
मंजिल, “डी” ब्लॉक, (उत्तर और दक्षिण)
No.4, Rajiv Gandhi Salai / नं.4, राजीव गांधी सलाई
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Joint Director / संयुक्त निदेशक
Centre for Development of Advanced Computing(C-DAC) / प्रगत संगणन विकास
केन्द्र(सी-डैक)
Tidel Park”, 8th Floor, “D” Block, (North &South) / “टाइडल पार्क”,8वीं
मंजिल, “डी” ब्लॉक, (उत्तर और दक्षिण)
No.4, Rajiv Gandhi Salai / नं.4, राजीव गांधी सलाई
Taramani / तारामणि
Chennai / चेन्नई – 600113
Ph.No.:044-22542226/27
Fax No.: 044-22542294
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)
Tidel Park”, 8th Floor, “D” Block, (North &South) / “टाइडल पार्क”,8वीं
मंजिल, “डी” ब्लॉक, (उत्तर और दक्षिण)
No.4, Rajiv Gandhi Salai / नं.4, राजीव गांधी सलाई
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Chennai / चेन्नई – 600113
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