CentOS - Jan 2015 - C6 server responding extremely slow on ssh interactive

I have a C6 server acting as a kvm-host.

When connecting with ssh the console is extremely slow and hangs for minutes at
a time. Connecting to this server is not the problem.

If I use: ssh root at host "whatever" I got immediate response even
when interactive consoles opened with ssh are hanging.

    Linux [...] 2.6.32-504.3.3.el6.x86_64 #1 SMP Wed Dec 17 01:55:02 UTC 2014
x86_64 x86_64 x86_64 GNU/Linux

                  total       used       free     shared buffers     cached
    Mem:            47         35         11 0          0          0
    -/+ buffers/cache:         35         11
    Swap:            7          0          7

    Filesystem            Size  Used Avail Use% Mounted on
    /dev/mapper/vg-lv_root
                            50G  6,4G   41G  14% /
    tmpfs                  24G     0   24G   0% /dev/shm
    /dev/sda1             477M  123M  329M  28% /boot

      13:33:34 up 1 day, 18:30,  2 users,  load average: 3.39, 2.53, 2.36

(it's an 8-core)

Nothing particular in log/messages.

The vm's are running normally and they are not showing the same behaviour.

Can anybody give me a pointer?

Thanks
Patrick

On 28-01-2015 11:15, Patrick Bervoets wrote:
> I have a C6 server acting as a kvm-host.
>
> When connecting with ssh the console is extremely slow and hangs for
> minutes at a time. Connecting to this server is not the problem.
>
> If I use: ssh root at host "whatever" I got immediate response
even when
> interactive consoles opened with ssh are hanging.
Sorry, is it hanging during the session or while attempting to establish 
a new one? If this last, it may be dns and ssh -v may help. The former 
is weird, I don't think I ever saw it.

   Marcelo

Op 28-01-15 om 17:20 schreef Marcelo Ricardo Leitner:
> On 28-01-2015 11:15, Patrick Bervoets wrote:
>> I have a C6 server acting as a kvm-host.
>>
>> When connecting with ssh the console is extremely slow and hangs for
>> minutes at a time. Connecting to this server is not the problem.
>>
>> If I use: ssh root at host "whatever" I got immediate
response even when
>> interactive consoles opened with ssh are hanging.
>
> Sorry, is it hanging during the session or while attempting to establish a
new one? If this last, it may be dns and ssh -v may help. The former is weird, I
don't think I ever saw it.
>
>   Marcelo
>
Marcelo,

It hangs during the session. Once I'm logged in and beginning to type it
displays 3-5 chars and then hangs for up to 15 minutes, a few more chars, wait,
and so on.
Checked my resolv.conf; added 'options single-request-reopen' though I
don't know if that is helping.

Yes it is weird; even more that individual commands sent with ssh gives
immediate respons.

Thanks
Patrick

On 01/28/2015 05:15 AM, Patrick Bervoets wrote:
>
> When connecting with ssh the console is extremely slow and hangs for
> minutes at a time
Check for IP address conflicts in the server's network.

For IPv4:
# arping -D -I <interface> <address>

Op 28-01-15 om 20:17 schreef Gordon Messmer:
> On 01/28/2015 05:15 AM, Patrick Bervoets wrote:
>>
>> When connecting with ssh the console is extremely slow and hangs for
>> minutes at a time
>
> Check for IP address conflicts in the server's network.
>
> For IPv4:
> # arping -D -I <interface> <address>
>
ARPING 192.168.1.15 from 0.0.0.0 br0
Unicast reply from 192.168.1.15 [AC:16:2D:72:67:D4]  0.723ms
Sent 1 probes (1 broadcast(s))
Received 1 response(s)

Thanks anyway
Patrick