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<div class="moz-cite-prefix">On 16/06/13 18:47, Luca Fornasari
wrote:<br>
</div>
<blockquote
cite="mid:CALEH7n_Yg=vWGsW8vprGk-sKx6sQV+i_rnHL9ZieA3j+wHBdZw@mail.gmail.com"
type="cite">
<div dir="ltr">
<div>On Sun, Jun 16, 2013 at 6:44 AM, cesar <span dir="ltr"><<a
moz-do-not-send="true" href="mailto:brain@click.com.py"
target="_blank">brain@click.com.py</a>></span> wrote:<br>
</div>
<div class="gmail_extra">
<div class="gmail_quote"> <br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">And
about DRBD over a direct connection in mode round robin,
can you give me<br>
links or comments about this case? (This is very important
for me because I<br>
will lose connection speed if I change of balance-rr to
active-backup).<br>
</blockquote>
<div><br>
</div>
<div><a moz-do-not-send="true"
href="https://www.kernel.org/doc/Documentation/networking/bonding.txt"
target="_blank">https://www.kernel.org/doc/Documentation/networking/bonding.txt</a><br>
</div>
<div>
<pre style="white-space:pre-wrap;word-wrap:break-word">balance-rr: This mode is the only mode that will permit a single
TCP/IP connection to stripe traffic across multiple
interfaces. It is therefore the only mode that will allow a
single TCP/IP stream to utilize more than one interface's
worth of throughput. This comes at a cost, however: the
striping generally results in peer systems receiving packets out
of order, causing TCP/IP's congestion control system to kick
in, often by retransmitting segments.</pre>
</div>
<div>The problem is you have out of order packets and it
doesn't help if you start to play around with <span
style="white-space:pre-wrap">net.ipv4.tcp_reordering
sysctl parameter</span> </div>
<div>because there will always be a chance to have out of
order packets. Ordered packets are indeed fundamental to
DRBD.</div>
<div>In DRBD world the bonding driver is used to achieve HA
using active/backup or 802.3ad. Neither of which will
boost your performance (802.3ad can improve performance if
and only if you have a great number of TCP connections but
that's not the case with your DRBD scenario).</div>
<br>
</div>
</div>
</div>
</blockquote>
Hi,<br>
<br>
It was my understanding that this was only the case if switches were
involved, and especially different switches. When you have 2 (or
more ports) on one machine connected via crossover cables to another
server with an equal number of ports (obviously), and you configure
both sides with RR, then all packets should arrive in order. <br>
<br>
Since packet 1 is sent on eth0, and packet 2 on eth1 from server 1<br>
Server 2 will receive packet 1 on eth0 and packet 2 on eth1 in the
same order.<br>
<br>
If you had switch1 between the two machines on eth0, and switch2
between the machines on eth1, then it is very possible the switch
will introduce different amounts of delay, therefore causing out of
order packets.<br>
<br>
At least, this was my understanding after some recent detailed
reading/research into these matters. If this is still wrong, even
for a set of direct cross over connections, please educate both me
and the OP.<br>
<br>
Regards,<br>
Adam<br>
<br>
<pre class="moz-signature" cols="72">--
Adam Goryachev
Website Managers
<a class="moz-txt-link-abbreviated" href="http://www.websitemanagers.com.au">www.websitemanagers.com.au</a>
</pre>
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