[Lustre-discuss] Same performance Infiniband and Ethernet

Hammitt, Charles Allen chammitt at email.unc.edu
Mon May 19 04:24:31 PDT 2014


Two things:

1)  Linux write cache is likely getting in the way; you'd be better off trying to write directly forgoing cache
2)  you need to write a much bigger file than 1GB; try 50GB


Then as the previous poster said, maybe your disks aren't up to snuff or are misconfigured.  
Also, very interesting, and impossible, to get 154MB/s out of a Single GbE link [128MB/s].  Should be more like 100-115.  Less this is 10/40GbE...if so... again, start at #1 and #2.




Regards,

Charles




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Charles Hammitt
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-----Original Message-----
From: lustre-discuss-bounces at lists.lustre.org [mailto:lustre-discuss-bounces at lists.lustre.org] On Behalf Of Vsevolod Nikonorov
Sent: Monday, May 19, 2014 6:54 AM
To: lustre-discuss at lists.lustre.org
Subject: Re: [Lustre-discuss] Same performance Infiniband and Ethernet

What disks do your OSTs have? Maybe you have reached your disk performance limit, so Infiniband gives some speedup, but very small. Did you try to enable striping on your Lustre filesystem? For instance, you can type something like this: "lfs setstripe -c <count of stripes> /mnt/lustre/somefolder" and than copy a file into that folder.

Also, there's an opinion that sequence of zeros is not a good way to test a performance, so maybe you should try using /dev/urandom (which is rather slow, so it's better to have a pre-generated "urandom" file in /ram, or /dev/shm, or where your memory space is mounted to, and copy that file to Lustre filesystem as a test).



Pardo Diaz, Alfonso писал 2014-05-19 14:33:
> Hi,
> 
> I have migrated my Lustre 2.2 to 2.5.1 and I have equipped my OSS/MDS 
> and clients with Infiniband QDR interfaces.
> I have compile lustre with OFED 3.2 and I have configured lnet module
> with:
> 
> options lent networks=“o2ib(ib0),tcp(eth0)”
> 
> 
> But when I try to compare the lustre performance across Infiniband 
> (o2ib), I get the same performance than across ethernet (tcp):
> 
> INFINIBAND TEST:
> dd if=/dev/zero of=test.dat bs=1M count=1000
> 1000+0 records in
> 1000+0 records out
> 1048576000 bytes (1,0 GB) copied, 5,88433 s, 178 MB/s
> 
> ETHERNET TEST:
> dd if=/dev/zero of=test.dat bs=1M count=1000
> 1000+0 records in
> 1000+0 records out
> 1048576000 bytes (1,0 GB) copied, 5,97423 s, 154 MB/s
> 
> 
> And this is my scenario:
> 
> - 1 MDs with SSD RAID10 MDT
> - 10 OSS with 2 OST per OSS
> - Infiniband interface in connected mode
> - Centos 6.5
> - Lustre 2.5.1
> - Striped filesystem “lfs setstripe -s 1M -c 10"
> 
> 
> I know my infiniband running correctly, because if I use IPERF3 
> between client and servers I got 40Gb/s by infiniband and 1Gb/s by 
> ethernet connections.
> 
> 
> 
> Could you help me?
> 

> 
> Regards,
> 
> 
> 
> 
> 
> Alfonso Pardo Diaz
> System Administrator / Researcher
> c/ Sola nº 1; 10200 Trujillo, ESPAÑA
> Tel: +34 927 65 93 17 Fax: +34 927 32 32 37
> 
> 
> 
> 
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