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[kolla][nova][neutron] Access to VMs is slow when running on a remote compute host


Hi Alex,
yeah, it was the first suspect also based on the various research on
internet.
I currently have the "useDNS" set to no but still the issue persists.

/G

On Mon, 15 Jul 2019 at 18:46, Alex Schultz <aschultz at redhat.com> wrote:

>
> On Mon, Jul 15, 2019 at 10:40 AM Giuseppe Sannino <
> km.giuseppesannino at gmail.com> wrote:
>
>> Hi Sean,
>> the ssh to localhost is slow as well.
>> "telnet localhost" is also slow.
>>
>>
> Are you having dns issues? Historically if you have UseDNS set to true and
> your dns servers are bad it can just be slow to connect as it tries to do
> the reverse lookup.
>
>
>> /Giuseppe
>>
>> On Mon, 15 Jul 2019 at 18:18, Sean Mooney <smooney at redhat.com> wrote:
>>
>>> On Mon, 2019-07-15 at 16:29 +0200, Giuseppe Sannino wrote:
>>> > Hi!
>>> > first of all, thanks for the fast replies. I do appreciate that.
>>> >
>>> > I did some more test trying to figure out the issue.
>>> > - Set UseDNS to "no" in sshd_config  => Issue persists
>>> > - Installed and configured Telnet => Telnet login is slow as well
>>> >
>>> > From the "top" or "auth.log"nothing specific popped up. I can sshd
>>> taking
>>> > some cpu for a short while but nothing more than that.
>>> >
>>> > Once logged in the VM is not too slow. CLI doesn't get stuck or
>>> similar.
>>> > One thing worthwhile to mention, it seems like the writing throughput
>>> on
>>> > the disk is a bit slow: 67MB/s  wrt around 318MB/s of another VM
>>> running on
>>> > a "datacenter" Openstack installation.
>>> unless you see iowait in the guest its likely not related to the disk
>>> speed.
>>> you might be able to improve the disk performace by changeing the chache
>>> mode
>>> but unless you are seeing io wait that is just an optimisation to try
>>> later.
>>>
>>> when you are logged into the vm have you tried ssh again via localhost to
>>> determin if the long login time is related to the network or the vm.
>>>
>>> if its related to the network it will be fast over localhost
>>> if its related to the vm, e.g. because of disk, cpu load, memory load or
>>> ssh server configuration
>>> then the local ssh will be slow.
>>>
>>> >
>>> > The Cinder Volume docker is running on the Compute Host and Cinder is
>>> using
>>> > the filesystem as backend.
>>> >
>>> > BR
>>> > /Giuseppe
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> >
>>> > On Fri, 12 Jul 2019 at 17:41, Slawek Kaplonski <skaplons at redhat.com>
>>> wrote:
>>> >
>>> > > Hi,
>>> > >
>>> > > I suspect some problems with names resolving. Can You check if You
>>> have
>>> > > also such delay when doing e.g. â??sudoâ?? commands after You ssh to the
>>> > > instance?
>>> > >
>>> > > > On 12 Jul 2019, at 16:23, Brian Haley <haleyb.dev at gmail.com>
>>> wrote:
>>> > > >
>>> > > >
>>> > > >
>>> > > > On 7/12/19 9:57 AM, Giuseppe Sannino wrote:
>>> > > > > Hi community,
>>> > > > > I need your help ,tips, advices.
>>> > > > > *> Environment <*
>>> > > > > I have deployed Openstack "Stein" using the latest kolla-ansible
>>> on the
>>> > >
>>> > > following deployment topology:
>>> > > > > 1) OS Controller running as VM on a "cloud" location
>>> > > > > 2) OS Compute running on a baremetal server remotely (wrt OS
>>> > >
>>> > > Controller) location
>>> > > > > 3) Network node running on the Compute host
>>> > > > > As per the above info, Controller and compute run on two
>>> different
>>> > >
>>> > > networks.
>>> > > > > Kolla-Ansible is not really designed for such scenario but after
>>> > >
>>> > > manipulating the globals.yml and the inventory files (basically I
>>> had to
>>> > > move node specific network settings from the globals to the inventory
>>> > > file), eventually the deployment works fine.
>>> > > > > *> Problem <*
>>> > > > > I have no specific issue working with this deployment except the
>>> > >
>>> > > following:
>>> > > > > "SSH connection to the VM is quite slow".
>>> > > > > It takes around 20 seconds for me to log into the VM (Ubuntu,
>>> CentOS,
>>> > >
>>> > > whatever).
>>> > > >
>>> > > > But once logged-in things are OK?  For example, an scp stalls the
>>> same
>>> > >
>>> > > way, but the transfer is fast?
>>> > > >
>>> > > > > *> Observations <*
>>> > > > >  * Except for the slowness during the SSH login, I don't have any
>>> > > > >    further specific issue working with this envirorment
>>> > > > >  * With the Network on the Compute I can turn the OS controller
>>> off
>>> > > > >    with no impact on the VM. Still the connection is slow
>>> > > > >  * I tried different type of images (Ubuntu, CentOS, Windows)
>>> always
>>> > > > >    with the same result.
>>> > > > >  * SSH connection is slow even if I try to login into the VM
>>> within the
>>> > > > >    IP Namespace
>>> > > > > From the ssh -vvv, I can see that the authentication gets stuck
>>> here:
>>> > > > > debug1: Authentication succeeded (publickey).
>>> > > > > Authenticated to *****
>>> > > > > debug1: channel 0: new [client-session]
>>> > > > > debug3: ssh_session2_open: channel_new: 0
>>> > > > > debug2: channel 0: send open
>>> > > > > debug3: send packet: type 90
>>> > > > > debug1: Requesting no-more-sessions at openssh.com <mailto:
>>> > >
>>> > > no-more-sessions at openssh.com>
>>> > > > > debug3: send packet: type 80
>>> > > > > debug1: Entering interactive session.
>>> > > > > debug1: pledge: network
>>> > > > > > > > > > 10 to 15 seconds later
>>> > > >
>>> > > > What is sshd doing at this time?  Have you tried enabling debug or
>>> > >
>>> > > running tcpdump when a new connection is attempted?  At first glance
>>> I'd
>>> > > say it's a DNS issue since it eventually succeeds, the logs would
>>> help to
>>> > > point in a direction.
>>> > > >
>>> > > > -Brian
>>> > > >
>>> > > >
>>> > > > > debug3: receive packet: type 80
>>> > > > > debug1: client_input_global_request: rtype
>>> hostkeys-00 at openssh.com
>>> > >
>>> > > <mailto:hostkeys-00 at openssh.com> want_reply 0
>>> > > > > debug3: receive packet: type 91
>>> > > > > debug2: callback start
>>> > > > > debug2: fd 3 setting TCP_NODELAY
>>> > > > > debug3: ssh_packet_set_tos: set IP_TOS 0x10
>>> > > > > debug2: client_session2_setup: id 0
>>> > > > > debug2: channel 0: request pty-req confirm 1
>>> > > > > Have you ever experienced such issue ?
>>> > > > > Any suggestion?
>>> > > > > Many thanks
>>> > > > > /Giuseppe
>>> > >
>>> > > â??
>>> > > Slawek Kaplonski
>>> > > Senior software engineer
>>> > > Red Hat
>>> > >
>>> > >
>>>
>>>
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