[Beowulf] What are people seeing performance-wise for NFS over 10GbE

Jan Heichler jan.heichler at gmx.net
Thu Feb 28 13:05:13 PST 2008

Hallo Joe,

Donnerstag, 28. Februar 2008, meintest Du:

>> The best i saw for NFS over 10 GE was about 350-400 MB/s write and about 450 MB/s read.
>> Single server to 8 simultaneous accessing clients (aggregated performance). 

The clients had a 1 gig uplink...  

JL> Hi Jan:

JL>    Ok. Thanks.  This is quite helpful.

>> On the blockdevice i got 550 MB/s write and 1.1 GB/s read performance. 

JL> Using iSCSI?  To real disks or ramdisk/nullio? Most of the benchmarks I
JL> have seen online have been to nullio or ramdisks.  We are going to real
JL> disks.

Real disks. 16 SAS 15k Disks on a LSI 8888 Controller in RAID-5. Connected through a x4 SAS connection on a backplane. Because of the x4 SAS connection the read rate is limited to 1.1 gig/s - with discrete connections to the drives the read speed should be 50% higher. 

I couldn't get a tmpfs exported over NFS - but i did not try very hard on that because it does not make any sense for practical usage - just to find out if NFS itself is the bottleneck.

I tried several configs including software raid-0. The performance was a disaster compared to theoretical values. 

>> JL> kernel on both sides, jumbo frames enabled. No switch, just
>> JL> a CX4 cable.

>> rsize/wsize are set to? 

JL> I tried a range: 8k through 64k

Okay. That was the most important improvement i could do. The first kernel i used did not allow to go over 8k - with 32k if was much faster. 

>> NFS3 or NFS4? 

JL> 3.

I saw no performance improve with NFS4 i have to say. Everybody i talked to pointed at the bad NFS performance of linux (and many said: use solaris - it is much faster ;-) )

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