New subject: [ceph-users]: Ceph Nautius not working after setting MTU 9000

29 May 2020

      Hello.

A few days ago I offered to share the notes I've compiled on network 
tuning.  Right now it's a Google Doc:

https://docs.google.com/document/d/1nB5fzIeSgQF0ti_WN-tXhXAlDh8_f8XF9GhU7J1l...

I've set it up to allow comments and I'd be glad for questions and 
feedback.  If Google Docs not an acceptable format I'll try to put it up 
somewhere as HTML or Wiki.  Disclosure: some sections were copied 
verbatim from other sources.

Regarding the current discussion about iperf, the likely bottleneck is 
buffering.  There is a per-NIC output queue set with 'ip link' and a per 
CPU core input queue set with 'sysctl'.  Both should be set to some 
multiple of the frame size based on calculations related to link speed 
and latency.  Jumping from 1500 to 9000 could negatively impact 
performance because one buffer or the other might be 1500 bytes short of 
a low multiple of 9000.

It would be interesting to see the iperf tests repeated with 
corresponding buffer sizing.  I will perform this experiment as soon as 
I complete some day-job tasks.

-Dave

Dave Hall
Binghamton University
kdhall@binghamton.edu
607-760-2328 (Cell)
607-777-4641 (Office)

On 5/27/2020 6:51 AM, EDH - Manuel Rios wrote:
...
Anyone can share their table with other MTU values?
Also interested into Switch CPU load
KR,
Manuel
-----Mensaje original-----
De: Marc Roos <M.Roos@f1-outsourcing.eu>
Enviado el: miércoles, 27 de mayo de 2020 12:01
Para: chris.palmer <chris.palmer@pobox.com>; paul.emmerich <paul.emmerich@croit.io>
CC: amudhan83 <amudhan83@gmail.com>; anthony.datri <anthony.datri@gmail.com>; ceph-users <ceph-users@ceph.io>; doustar <doustar@rayanexon.ir>; kdhall <kdhall@binghamton.edu>; sstkadu <sstkadu@gmail.com>
Asunto: [ceph-users] Re: [External Email] Re: Ceph Nautius not working after setting MTU 9000
Interesting table. I have this on a production cluster 10gbit at a
datacenter (obviously doing not that much).
[@]# iperf3 -c 10.0.0.13 -P 1 -M 9000
Connecting to host 10.0.0.13, port 5201
[  4] local 10.0.0.14 port 52788 connected to 10.0.0.13 port 5201
[ ID] Interval           Transfer     Bandwidth       Retr  Cwnd
[  4]   0.00-1.00   sec  1.14 GBytes  9.77 Gbits/sec    0    690 KBytes
[  4]   1.00-2.00   sec  1.15 GBytes  9.90 Gbits/sec    0   1.08 MBytes
[  4]   2.00-3.00   sec  1.15 GBytes  9.88 Gbits/sec    0   1.08 MBytes
[  4]   3.00-4.00   sec  1.15 GBytes  9.88 Gbits/sec    0   1.08 MBytes
[  4]   4.00-5.00   sec  1.15 GBytes  9.88 Gbits/sec    0   1.08 MBytes
[  4]   5.00-6.00   sec  1.15 GBytes  9.90 Gbits/sec    0   1.21 MBytes
[  4]   6.00-7.00   sec  1.15 GBytes  9.89 Gbits/sec    0   1.21 MBytes
[  4]   7.00-8.00   sec  1.15 GBytes  9.88 Gbits/sec    0   1.21 MBytes
[  4]   8.00-9.00   sec  1.15 GBytes  9.89 Gbits/sec    0   1.21 MBytes
[  4]   9.00-10.00  sec  1.15 GBytes  9.89 Gbits/sec    0   1.21 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth       Retr
[  4]   0.00-10.00  sec  11.5 GBytes  9.87 Gbits/sec    0
sender
[  4]   0.00-10.00  sec  11.5 GBytes  9.87 Gbits/sec
receiver
-----Original Message-----
Subject: Re: [ceph-users] Re: [External Email] Re: Ceph Nautius not
working after setting MTU 9000
To elaborate on some aspects that have been mentioned already and add
some others::
*	Test using iperf3.
*	Don't try to use jumbos on networks where you don't have complete
control over every host. This usually includes the main ceph network.
It's just too much grief. You can consider using it for limited-access
networks (e.g. ceph cluster network, hypervisor migration network, etc)
where you know every switch & host is tuned correctly. (This works even
when those nets share a vlan trunk with non-jumbo vlans - just set the
max value on the trunk itself, and individual values on each vlan.)
*	If you are pinging make sure it doesn't fragment otherwise you
will get misleading results: e.g. ping -M do -s 9000 x.x.x.x
*	Do not assume that 9000 is the best value. It depends on your
NICs, your switch, kernel/device parameters, etc. Try different values
(using iperf3). As an example the results below are using a small cheap
Mikrotek 10G switch and HPE 10G NICs. It highlights how in this
configuration 9000 is worse than 1500, but that 5139 is optimal yet 5140
is worst. The same pattern (obviously with different values) was
apparent when multiple tests were run concurrently. Always test your own
network in a controlled manner. And of course if you introduce anything
different later on, test again. With enterprise-grade kit this might not
be so common, but always test if you fiddle.
MTU  Gbps  (actual data transfer values using iperf3)  - one particular
configuration only
9600 8.91 (max value)
9000 8.91
8000 8.91
7000 8.91
6000 8.91
5500 8.17
5200 7.71
5150 7.64
5140 7.62
5139 9.81 (optimal)
5138 9.81
5137 9.81
5135 9.81
5130 9.81
5120 9.81
5100 9.81
5000 9.81
4000 9.76
3000 9.68
2000 9.28
1500 9.37 (default)
Whether any of this will make a tangible difference for ceph is moot. I
just spend a little time getting the network stack correct as above,
then leave it. That way I know I am probably getting some benefit, and
not doing any harm. If you blindly change things you may well do harm
that can manifest itself in all sorts of ways outside of Ceph. Getting
some test results for this using Ceph will be easy; getting MEANINGFUL
results that way will be hard.
Chris
On 27/05/2020 09:25, Marc Roos wrote:
I would not call a ceph page, a random tuning tip. At least I hope
they
  are not. NVMe-only with 100Gbit is not really a standard setup. I
assume
  with such setup you have the luxury to not notice many
optimizations.
What I mostly read is that changing to mtu 9000 will allow you to
better
  saturate the 10Gbit adapter, and I expect this to show on a low end
busy
  cluster. Don't you have any test results of such a setup?
-----Original Message-----
Subject: Re: [ceph-users] Re: [External Email] Re: Ceph Nautius not
working after setting MTU 9000
Don't optimize stuff without benchmarking *before and after*, don't
apply random tuning tipps from the Internet without benchmarking
them.
My experience with Jumbo frames: 3% performance. On a NVMe-only
setup
  with 100 Gbit/s network.
Paul
--
  Paul Emmerich
Looking for help with your Ceph cluster? Contact us at
https://croit.io
croit GmbH
  Freseniusstr. 31h
  81247 München
  www.croit.io
  Tel: +49 89 1896585 90
On Tue, May 26, 2020 at 7:02 PM Marc Roos
<M.Roos@f1-outsourcing.eu> <mailto:M.Roos@f1-outsourcing.eu>
  wrote:
Look what I have found!!! :)
      https://ceph.com/geen-categorie/ceph-loves-jumbo-frames/
-----Original Message-----
      From: Anthony D'Atri [mailto:anthony.datri@gmail.com]
      Sent: maandag 25 mei 2020 22:12
      To: Marc Roos
      Cc: kdhall; martin.verges; sstkadu; amudhan83; ceph-users;
doustar
      Subject: Re: [ceph-users] Re: [External Email] Re: Ceph
Nautius not
working after setting MTU 9000
Quick and easy depends on your network infrastructure.
Sometimes
  it is
      difficult or impossible to retrofit a live cluster without
  disruption.
> On May 25, 2020, at 1:03 AM, Marc Roos
<M.Roos@f1-outsourcing.eu> <mailto:M.Roos@f1-outsourcing.eu>
wrote:
      >
      > 
      > I am interested. I am always setting mtu to 9000. To be
honest I
      > cannot imagine there is no optimization since you have less
  interrupt
      > requests, and you are able x times as much data. Every time
there
> something written about optimizing the first thing mention
is
  changing
> to the mtu 9000. Because it is quick and easy win.
      >
      >
      >
      >
      > -----Original Message-----
      > From: Dave Hall [mailto:kdhall@binghamton.edu]
      > Sent: maandag 25 mei 2020 5:11
      > To: Martin Verges; Suresh Rama
      > Cc: Amudhan P; Khodayar Doustar; ceph-users
      > Subject: [ceph-users] Re: [External Email] Re: Ceph Nautius
not
      > working after setting MTU 9000
      >
      > All,
      >
      > Regarding Martin's observations about Jumbo Frames....
      >
      > I have recently been gathering some notes from various
internet
      > sources regarding Linux network performance, and Linux
  performance in
      > general, to be applied to a Ceph cluster I manage but also
to the
  rest
> of the Linux server farm I'm responsible for.
      >
      > In short, enabling Jumbo Frames without also tuning a number
of
  other
      > kernel and NIC attributes will not provide the performance
  increases
      > we'd like to see.  I have not yet had a chance to go through
the
  rest
      > of the testing I'd like to do, but  I can confirm (via
iperf3)
  that
      > only enabling Jumbo Frames didn't make a significant
difference.
      >
      > Some of the other attributes I'm referring to are incoming
and
      > outgoing buffer sizes at the NIC, IP, and TCP levels,
interrupt
      > coalescing, NIC offload functions that should or shouldn't
be
  turned
      > on, packet queuing disciplines (tc), the best choice of TCP
  slow-start
> algorithms, and other TCP features and attributes.
      >
      > The most off-beat item I saw was something about adding
IPTABLES
  rules
> to bypass CONNTRACK table lookups.
      >
      > In order to do anything meaningful to assess the effect of
all of
> these settings I'd like to figure out how to set them all
via
  Ansible
      > - so more to learn before I can give opinions.
      >
      > -->  If anybody has added this type of configuration to Ceph
Ansible,
      > I'd be glad for some pointers.
      >
      > I have started to compile a document containing my notes.
It's
  rough,
> but I'd be glad to share if anybody is interested.
      >
      > -Dave
      >
      > Dave Hall
      > Binghamton University
      >
      >> On 5/24/2020 12:29 PM, Martin Verges wrote:
      >>
      >> Just save yourself the trouble. You won't have any real
benefit
  from
      > MTU
      >> 9000. It has some smallish, but it is not worth the effort,
problems,
      > and
      >> loss of reliability for most environments.
      >> Try it yourself and do some benchmarks, especially with
your
  regular
      >> workload on the cluster (not the maximum peak performance),
then
  drop
      > the
      >> MTU to default ;).
      >>
      >> Please if anyone has other real world benchmarks showing
huge
      > differences
      >> in regular Ceph clusters, please feel free to post it here.
      >>
      >> --
      >> Martin Verges
      >> Managing director
      >>
      >> Mobile: +49 174 9335695
      >> E-Mail: martin.verges@croit.io
      >> Chat: https://t.me/MartinVerges
      >>
      >> croit GmbH, Freseniusstr. 31h, 81247 Munich
      >> CEO: Martin Verges - VAT-ID: DE310638492 Com. register:
  Amtsgericht
      >> Munich HRB 231263
      >>
      >> Web: https://croit.io
      >> YouTube: https://goo.gl/PGE1Bx
      >>
      >>
      >>> Am So., 24. Mai 2020 um 15:54 Uhr schrieb Suresh Rama
      >> <sstkadu@gmail.com> <mailto:sstkadu@gmail.com> :
      >>
      >>> Ping with 9000 MTU won't get response as I said and it
should
  be
      > 8972. Glad
      >>> it is working but you should know what happened to avoid
this
  issue
      > later.
      >>>
      >>>> On Sun, May 24, 2020, 3:04 AM Amudhan P
<amudhan83@gmail.com> <mailto:amudhan83@gmail.com>
      wrote:
      >>>
      >>>> No, ping with MTU size 9000 didn't work.
      >>>>
      >>>> On Sun, May 24, 2020 at 12:26 PM Khodayar Doustar
      > <doustar@rayanexon.ir> <mailto:doustar@rayanexon.ir>
      >>>> wrote:
      >>>>
      >>>>> Does your ping work or not?
      >>>>>
      >>>>>
      >>>>> On Sun, May 24, 2020 at 6:53 AM Amudhan P
  <amudhan83@gmail.com> <mailto:amudhan83@gmail.com>
      > wrote:
      >>>>>
      >>>>>> Yes, I have set setting on the switch side also.
      >>>>>>
      >>>>>> On Sat 23 May, 2020, 6:47 PM Khodayar Doustar,
      > <doustar@rayanexon.ir> <mailto:doustar@rayanexon.ir>
      >>>>>> wrote:
      >>>>>>
      >>>>>>> Problem should be with network. When you change MTU it
should be
      >>>> changed
      >>>>>>> all over the network, any single hup on your network
should
>>>>>>> speak
      > and
      >>>>>>> accept 9000 MTU packets. you can check it on your
hosts
  with
      >>> "ifconfig"
      >>>>>>> command and there is also equivalent commands for
other
      >>>> network/security
      >>>>>>> devices.
      >>>>>>>
      >>>>>>> If you have just one node which it not correctly
configured
  for
      > MTU
      >>>> 9000
      >>>>>>> it wouldn't work.
      >>>>>>>
      >>>>>>> On Sat, May 23, 2020 at 2:30 PM sinan@turka.nl
  <sinan@turka.nl> <mailto:sinan@turka.nl>
      >>> wrote:
      >>>>>>>> Can the servers/nodes ping eachother using large
packet
  sizes?
      >>>>>>>> I
      >>> guess
      >>>>>>>> not.
      >>>>>>>>
      >>>>>>>> Sinan Polat
      >>>>>>>>
      >>>>>>>>> Op 23 mei 2020 om 14:21 heeft Amudhan P
  <amudhan83@gmail.com> <mailto:amudhan83@gmail.com>
      > het
      >>>>>>>> volgende geschreven:
      >>>>>>>>> In OSD logs "heartbeat_check: no reply from OSD"
      >>>>>>>>>
      >>>>>>>>>> On Sat, May 23, 2020 at 5:44 PM Amudhan P
      > <amudhan83@gmail.com> <mailto:amudhan83@gmail.com>
      >>>>>>>> wrote:
      >>>>>>>>>> Hi,
      >>>>>>>>>>
      >>>>>>>>>> I have set Network switch with MTU size 9000 and
also in
  my
      >>> netplan
      >>>>>>>>>> configuration.
      >>>>>>>>>>
      >>>>>>>>>> What else needs to be checked?
      >>>>>>>>>>
      >>>>>>>>>>
      >>>>>>>>>>> On Sat, May 23, 2020 at 3:39 PM Wido den Hollander
<
      >>> wido@42on.com
      >>>>>>>> wrote:
      >>>>>>>>>>>
      >>>>>>>>>>>
      >>>>>>>>>>>> On 5/23/20 12:02 PM, Amudhan P wrote:
      >>>>>>>>>>>> Hi,
      >>>>>>>>>>>>
      >>>>>>>>>>>> I am using ceph Nautilus in Ubuntu 18.04 working
fine
  wit
      > MTU
      >>>> size
      >>>>>>>> 1500
      >>>>>>>>>>>> (default) recently i tried to update MTU size to
9000.
      >>>>>>>>>>>> After setting Jumbo frame running ceph -s is
timing
  out.
      >>>>>>>>>>> Ceph can run just fine with an MTU of 9000. But
there
  is
      >>> probably
      >>>>>>>>>>> something else wrong on the network which is
causing
  this.
      >>>>>>>>>>>
      >>>>>>>>>>> Check the Jumbo Frames settings on all the
switches as
  well
      > to
      >>>> make
      >>>>>>>> sure
      >>>>>>>>>>> they forward all the packets.
      >>>>>>>>>>>
      >>>>>>>>>>> This is definitely not a Ceph issue.
      >>>>>>>>>>>
      >>>>>>>>>>> Wido
      >>>>>>>>>>>
      >>>>>>>>>>>> regards
      >>>>>>>>>>>> Amudhan P
      >>>>>>>>>>>> _______________________________________________
      >>>>>>>>>>>> ceph-users mailing list -- ceph-users@ceph.io To
      >>>>>>>>>>>> unsubscribe send an email to
ceph-users-leave@ceph.io
      >>>>>>>>>>>>
      >>>>>>>>>>> _______________________________________________
      >>>>>>>>>>> ceph-users mailing list -- ceph-users@ceph.io To
  unsubscribe
>>>>>>>>>>> send an email to ceph-users-leave@ceph.io
      >>>>>>>>>>>
      >>>>>>>>> _______________________________________________
      >>>>>>>>> ceph-users mailing list -- ceph-users@ceph.io To
  unsubscribe
      >>>>>>>>> send an email to ceph-users-leave@ceph.io
      >>>>>>>> _______________________________________________
      >>>>>>>> ceph-users mailing list -- ceph-users@ceph.io To
  unsubscribe
      >>>>>>>> send an email to ceph-users-leave@ceph.io
      >>>>>>>>
      >>>> _______________________________________________
      >>>> ceph-users mailing list -- ceph-users@ceph.io To
unsubscribe
  send
      >>>> an email to ceph-users-leave@ceph.io
      >>>>
      >>> _______________________________________________
      >>> ceph-users mailing list -- ceph-users@ceph.io To
unsubscribe
  send an
>>> email to ceph-users-leave@ceph.io
      >>>
      >> _______________________________________________
      >> ceph-users mailing list -- ceph-users@ceph.io To
unsubscribe
  send an
      >> email to ceph-users-leave@ceph.io
      > _______________________________________________
      > ceph-users mailing list -- ceph-users@ceph.io To unsubscribe
send
  an
      > email to ceph-users-leave@ceph.io
      >
      > _______________________________________________
      > ceph-users mailing list -- ceph-users@ceph.io To unsubscribe
send
  an
      > email to ceph-users-leave@ceph.io
_______________________________________________
      ceph-users mailing list -- ceph-users@ceph.io
      To unsubscribe send an email to ceph-users-leave@ceph.io
_______________________________________________
  ceph-users mailing list -- ceph-users@ceph.io
  To unsubscribe send an email to ceph-users-leave@ceph.io
_______________________________________________
ceph-users mailing list -- ceph-users@ceph.io
To unsubscribe send an email to ceph-users-leave@ceph.io

Re: [ceph-users]: Ceph Nautius not working after setting MTU 9000

Dave Hall

Paul Emmerich

Dave Hall

Anthony D'Atri

Dave Hall

tags

participants (3)