Hi,
Have you run ibdiagnet to verify that your link width and speed is what you expect on all links? Thanks Rupert Dance Software Forge From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Monday, October 17, 2011 3:22 AM To: [email protected] Subject: [ewg] 200m cable results in slower rdma read performance? [ CC Anti-Virus checked ] Hi, In my test setup I have 3 servers of which 2 are residing in Datacenter1 and the other in Datacenter2. If I do a rdma test between datacenters, I get a much lower performance than if I would do the test between servers residing in the same datacenter. DC1: gpfsprod1n1, gpfsprod1n3 DC2: gpfsprod1n2 08:54:48|root@gpfsprod1n1:~ 0 # qperf -t 5 cic-gpfsprod1n2 rc_rdma_write_bw rc_rdma_write_bw: bw = 1.9 GB/sec 08:54:59|root@gpfsprod1n1:~ 0 # qperf -t 5 cic-gpfsprod1n3 rc_rdma_write_bw rc_rdma_write_bw: bw = 3.39 GB/sec The setup contains two pairs of edge switches (on each datacenter one pair) and two spine switches (each datacenter one), configured as a non blocking fat tree. So: The servers are connected to the edge switches. The spine switches are connected to all edge switches. These are the cables we are using: . Length 5m Vendor Name: WLGORE Code: QSFP+ Vendor PN: 498385-B24 Vendor Rev: D Vendor SN xxxx . Length 200m Vendor Name: MOLEX Code: QSFP+ Vendor PN: 106410-1200 Vendor Rev: A Vendor SN xxxx Can someone tell me why this is so? And maybe how I can solve this? Best regards, Koen Segers Enterprise Consultant Computacenter Services & Solutions Ikaroslaan 31 B-1930 Zaventem Belgium Tel: +32 2 704 94 67 Fax: +32 2 704 95 95 Mob: +32 497 909353 <mailto:[email protected]> [email protected] <http://www.computacenter.com/benelux> www.computacenter.com/benelux Visit us at http://www.computacenter.com/ Computacenter: Transforming IT service delivery. ========================== Disclaimer ================================== The information in this email is confidential, and is intended solely for the addressee(s). If you are not the intended recipient of this email please let us know by reply and then delete it from your system; you should not copy this message or disclose its contents to anyone. Due to the integrity risk of sending emails over the Internet, Computacenter will accept no liability for any comments and / or attachments contained within this email. ========================== Disclaimer ==================================
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