[Lustre-discuss] Seeking LNET router recomendations

[Hayes, Bob]

Are there any recommendations or guidelines for sizing a LNET routing facility.

~400 nodes, 8 OSS (dual socket E5 w/48GB RAM), 24 OST (10spindle RAID6 over SRP), 1 MGS/MDT

How much load does LNET routing put on a system?

If I make the 8 OSS systems do double duty as IB to IPoIB routers, will it have much impact on performance?

 

Bob Hayes

HPC Sys. Admin.

Intel Corp               Software & Services Group/DRD/CRT-DC           

DP3-307-H7            Tel:  (253)371-3040                                         

2800 N Center Dr    Fax: (253)371-4647                

DuPont WA 98327   bob....@intel.com

 

[Cliff White]

- An OSS really can't be a router, an OSS is an endpoint.  Topologically, it shouldn't work, you should re-think network layout.

- routing does place a load on the system, nodes doing routing should be dedicated to routing. 

- Load depends on traffic, basically you would have two hardware network interfaces, and ideally would

be sending max traffic through both. Impact would depend on hardware types, etc. 

WIth ~400 nodes, you would want a 'pool' of routers, size of pool would depend on your usage. 

cliffw

_______________________________________________
Lustre-discuss mailing list
Lustre-...@lists.lustre.org
http://lists.lustre.org/mailman/listinfo/lustre-discuss

--
cliffw

Support Guy

WhamCloud, Inc. 

www.whamcloud.com

[Cliff White]

Or to put it another way, if your OSS systems can already 'see' both IB and IPoIB networks the most cost

effective, high performance solution would be to add the necessary interface and put your MDS/MGS on both networks also.

No need for routers, no performance impact. 

cliffw

On Tue, Mar 13, 2012 at 11:25 AM, Hayes, Bob <bob....@intel.com> wrote:

_______________________________________________
Lustre-discuss mailing list
Lustre-...@lists.lustre.org
http://lists.lustre.org/mailman/listinfo/lustre-discuss

[Hayes, Bob]

When we added ‘options lnet networks=o2ib(ib0),tcp1(ib0)’ to the MDS and the OSS’s, communications from the nodes using tcp1 would not be returned by the OSS’s. We need to use two protocols over the same interface. Is this possible?

 

Bob Hayes

HPC Sys. Admin.

Intel Corp               Software & Services Group/DRD/CRT-DC           

DP3-307-H7            Tel:  (253)371-3040                                         

2800 N Center Dr    Fax: (253)371-4647                

DuPont WA 98327   bob....@intel.com

 

[Cliff White]

I don't think so, because any time two NIDs map to the same node, LNET will pick a 'best' interface (based on hop count and other things) and always use that interface.  In the normal case, you would subnet to separate the interfaces and use both, but you can't in this case as ib0 is the same IP for boh.  Really would be best to have a second IP for TCP.

cliffw