On Saturday, March 12, 2016 at 7:16:21 PM UTC-6, William Hermans wrote:

> *You might want to look at the NFS docs a bit more.  NFS has used UDP 
>> forever, TCP was only added in version 4 if memory serves, and it had to be 
>> specifically enabled.*
>>
>
> I do not really care what transport NFS uses at the lower level. NFS in 
> previous kernels was pretty much the fastest network storage protocol( on 
> this hardware ). I've tested many in the last 3 years or so on this 
> hardware. But here look . . .
>
> *dd to ramdisk* just to show how fast dd from /dev/zero can be on this 
> hardware
> william@beaglebone:~$ df -h ramfs/
> Filesystem      Size  Used Avail Use% Mounted on
> tmpfs           256M     0  256M   0% /home/william/ramfs
> william@beaglebone:~$ dd if=/dev/zero bs=1M count=200 
> of=/home/william/ramfs/test.log
> 200+0 records in
> 200+0 records out
> 209715200 bytes (210 MB) copied, 1.00041 s, 
>
> *210 MB/s*
> *dd to NFS share*
> william@beaglebone:~$ df -h ti/
> Filesystem                           Size  Used Avail Use% Mounted on
> 192.168.254.162:/home/william/share  136G   41G   88G  32% /home/william/ti
> william@beaglebone:~$ dd if=/dev/zero bs=1M count=1000 
> of=/home/william/ti/test.log
> 1000+0 records in
> 1000+0 records out
> 1048576000 bytes (1.0 GB) copied, 108.343 s, *9.7 MB/s*
>
> So  something to note here. Apparently in this test, TCP is faster than 
> UDP, since I'm using NFS v3 on the server side. Then since netcat is TCP . 
> . . but these are also really basic "tests", that may give a decent 
> indication of what is fastest, but may not be entirely accurate for 
> different situations.
>


See my comment about re-inventing TCP poorly when error 
detection/correction and re-transmission are added to something built on 
UDP.  As I said NFS has a lot of baggage along with some nice features, its 
all about using what's appropriate to the application and the target 
environment.   I've pretty much always been in  mixed Windows/Linux 
environments (with Windows machines dominant, so any compatibility stuff 
had to be on the Linux side by default from the system 
administration overhead alone) so SAMBA has made more sensed to me than NFS.

As to ramdisks, if the communicating processes are on the same machine, its 
hard to beat shared memory and semaphores for IPC.

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