[Lustre-discuss] Lustre over two TCP interfaces

White, Cliff cliff.white at intel.com
Tue Jun 25 11:24:30 PDT 2013

From: Alfonso Pardo <alfonso.pardo at ciemat.es<mailto:alfonso.pardo at ciemat.es>>
Date: Tuesday, June 25, 2013 5:22 AM
To: Michael Shuey <shuey at purdue.edu<mailto:shuey at purdue.edu>>
Cc: WC-Discuss <WC-Discuss.Migration at intel.com<mailto:WC-Discuss.Migration at intel.com>>, "lustre-discuss at lists.lustre.org<mailto:lustre-discuss at lists.lustre.org>" <lustre-discuss at lists.lustre.org<mailto:lustre-discuss at lists.lustre.org>>
Subject: Re: [Lustre-discuss] Lustre over two TCP interfaces

thank Michael,

This is my second step, I will change the lnet with “options lnet networks=tcp0(bond0,bond1)” because my machines has 4 nics. I have a bond0 and bond1 with LACP. I need to comunicate the clients with two network for HA network.

If the bond0 network is down, the clients can reach the OSS by the second network bond1.

If I change the modprobe with “options lnet networks=tcp0(bond0),tcp1(bond1)”, how the clients mount the filesystem to reach the OSS by two network?

The issue here is not Lustre, but TCP/IP routing. If you have two IP address on a single node, and another machine can see both addresses, typically one interface is picked as 'closer' and traffic flows through one interface only.  This is outside of Lustre, and will happen with any application.

The client mount address is still the address exported by the MGS. That does not change with bonding, except you use the bond IP instead of the individual IPs.  When you configure multiple address and.or networks for a server node (MGS,MDS, OSS) the clients are given the list at mount time, and will independently  try each address in the list until they connect.  Again, the start with the 'closest' address by hop rules.

From: Michael Shuey<mailto:shuey at purdue.edu>
Sent: Tuesday, June 25, 2013 2:14 PM
To: Alfonso Pardo<mailto:alfonso.pardo at ciemat.es>
Cc: lustre-discuss at lists.lustre.org<mailto:lustre-discuss at lists.lustre.org> ; WC-Discuss<mailto:WC-Discuss.Migration at intel.com>
Subject: Re: [Lustre-discuss] Lustre over two TCP interfaces

Different interfaces need to be declared with different LNET networks - something like "networks=tcp0(eth0),tcp1(eth1)".  Of course, that assumes your clients are configured to use a mix of tcp0 and tcp1 for connections (with each client only using one of the two).  This is really only useful in corner cases, when you're doing something strange; if eth0 and eth1 are in the same subnet (as in your example), this is almost certainly not productive.

A better bet might be to use a single LNET, and bond the two interfaces together - either as an active/passive pair, or active/active (e.g., LACP).  Then you'd declare networks=tcp0(bond0), give the bond a single IP address, and client traffic would be split across the two members in the bond more like you probably expect (given the limits of the bond protocol you're using).

Mike Shuey

On Tue, Jun 25, 2013 at 8:06 AM, Alfonso Pardo <alfonso.pardo at ciemat.es<mailto:alfonso.pardo at ciemat.es>> wrote:
hello friends,

I need to comunicate my OSS by two ethernet TCP interfaces: eth0 and eth1.

I have configured this feature in my modprobe.d with:

“options lnet networks=tcp0(eth0,eth1)”

And I can see two interfaces with:

lctl --net tcp interface_list
sa-d4-01.ceta-ciemat.es<http://sa-d4-01.ceta-ciemat.es>: (<>) npeer 0 nroute 2
sa-d4-01.ceta-ciemat.es<http://sa-d4-01.ceta-ciemat.es>: (<>) npeer 0 nroute 0

But, the clients only can communicate with the first interface:

lctl ping
12345-0 at lo
12345- at tcp
lctl ping
failed to ping at tcp: Input/output error

Any suggestions how to “enable” the second interface?

thank in advance

Alfonso Pardo Diaz
System Administrator / Researcher
c/ Sola nº 1; 10200 TRUJILLO, SPAIN
Tel: +34 927 65 93 17<tel:%2B34%20927%2065%2093%2017> Fax: +34 927 32 32 37

[CETA-Ciemat logo]<http://www.ceta-ciemat.es/>

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