[kolla][nova][neutron] Access to VMs is slow when running on a remote compute host
haleyb.dev at gmail.com
Fri Jul 12 14:23:18 UTC 2019
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)
> 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,
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.
> 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
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