Hi,
I've added ubuntu 20.04 nodes to my ceph octopus 15.2.17 baremetal deployed
cluster next to the centos 8 nodes and I see something interesting regarding
the disk usage, it is higher on ubuntu than on centos, however the cpu usage is
lower (on this picture you can see 4 nodes, each column is 1 node, the last
column is the ubuntu):
https://i.ibb.co/Tk5Srk6/image-2023-09-04-09-55-52-311.png
Could this be because of the missing HPC tuned profile on ubuntu 20.04?
On ubuntu 20.04 there isn't any HPC tuned profile, I've used the
latency-performance one which is the base of the HPC:
This is the latency performance:
[main]
summary=Optimize for deterministic performance at the cost of increased power
consumption
[cpu]
force_latency=1
governor=performance
energy_perf_bias=performance
min_perf_pct=100
[sysctl]
kernel.sched_min_granularity_ns=1000
vm.dirty_ratio=10
vm.dirty_background_ratio=3
vm.swappiness=10
kernel.sched_migration_cost_ns=500
The hpc tuned profile has these additional values on centos and on ubuntu 22.04:
[main]
summary=Optimize for HPC compute workloads
description=Configures virtual memory, CPU governors, and network settings for
HPC compute workloads.
include=latency-performance
[vm]
transparent_hugepages=always
[disk]
readahead=>4096
[sysctl]
vm.hugepages_treat_as_movable=0
vm.min_free_kbytes=135168
vm.zone_reclaim_mode=1
kernel.numa_balancing=0
net.core.busy_read=50
net.core.busy_poll=50
net.ipv4.tcp_fastopen=3
If someone is very god with these kernel parameter values, do you see something
that might be related to the high disk utilization?
Thank you
[https://i.ibb.co/Tk5Srk6/image-2023-09-04-09-55-52-311.png]
From: Milind Changire
Sent: Monday, August 7, 2023 11:38 PM
To: Szabo, Istvan (Agoda)
Cc: Ceph Users
Subject: Re: [ceph-users] Is it safe to add different OS but same ceph version
to the existing cluster?
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On Mon, Aug 7, 2023 at 8:23 AM Szabo, Istvan (Agoda)
wrote:
>
> Hi,
>
> I have an octopus cluster on the latest octopus version with mgr/mon/rgw/osds
> on centos 8.
> Is it safe to add an ubuntu osd host with the same octopus version?
>
> Thank you
Well, the ceph source bits surely remain the same. The binary bits
could be different due to better compiler support on the newer OS
version.
So assuming the new ceph is deployed on the same hardware platform
things should be stable.
Also, assuming that relevant OS tunables and ceph features and config
options have been configured to match the older deployment, the new
ceph deployment should just work fine and as expected.
Saying all this, I'd still recommend to test out the move one node at
a time rather than executing a bulk move.
Making a list of types of devices and checking driver support on the
new OS would also be a prudent thing to do.
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