NFS ridiculous speed

[Memorist]

Hi Guys

I've just built my 2nd NAS in the space of 2 weeks, i'm experiencing similar problems on both setups
Lets focus on this one.

Intel(R) Core(TM)2 Quad CPU Q9550 @ 2.83GHz
8G Ram

[root@freenas ~]# dd if=/dev/random of=/dev/null bs=1024 count=20k
20480+0 records in
20480+0 records out
20971520 bytes transferred in 0.290153 secs (72277447 bytes/sec)

Surely something is wrong here?

 

[cyberjock]

Yes there is something wrong. You have no idea what you are doing with the dd command. Look at your command closely(namely your if, your of, and your total bytes transferred in relation to your total system RAM). Your dd command isn't doing what you think is doing and I can't even figure out what you are trying to test. The only thing you are doing is testing non-physical devices.

 

[Memorist]

So is this better

dd if=/dev/zero of=(mnt location)tmp.dat bs=2048k count=50k
this will test my write speed to my device right?

what is the difference of /dev/zero and /dev/null?

does one just use 0's and the other ASCII character?

root@freenas ~]# dd if=/dev/zero of=/mnt/Volume1/Software/tmp.dat bs=2048 count
=50k
51200+0 records in
51200+0 records out
104857600 bytes transferred in 1.706191 secs (61457127 bytes/sec)

does this look better?

 

[cyberjock]

/dev/zero is a 0 generator(very fast too). /dev/null basically takes whatever input it has and sends the data to oblivion.

So what you were doing was generating 72MB/sec worth of zeros and outputting them to nothingness. Not a very useful test unless you want to know how fast your computer can make and destroy binary zeros.

If you look at the stickies.. (http://forums.freenas.org/showthread.php?981-Notes-on-Performance-Benchmarks-and-Cache) you'd see what is a good dd command to run for benchmarks.

 

[jgreco]

Actually his original test was using /dev/random, which is excruciatingly slow in comparison. Even a slow CPU ought to be able to do gigabytes per second - a busy N36L here gives me 3GBytes/sec while also handling backup loads. An unbusy E3-2609 shovels it around at 18GB/sec. It's actually fun to play with because you can see the effect of L2 cache by altering the block size, 1048576 works very well but a cache-busting 16777216 is much slower.

But to add a little more detail to Cyberjock's note, /dev/null is intended as an output channel - taking input from it results in End-Of-File.

 

[cyberjock]

You're right. I stand corrected. I had the whole /dev/zero stuck in my head and forgot he used /dev/random.

 

[Memorist]

Thanks guys.

Could i ask for a little guidance because i'm struggling to find posts to solve this.
The reason i'm checking my benchmarks is that when ever i try to wirelessly copy to my NAS finder (Cause i'm using a mac) hangs it is accessible then shows the progress of the copy taking 30mins to do a 300M file.

If i try to stream to my laptop video hang too. my router has a wifi ability to do 300m/sec

what should i be looking at?

 

[cyberjock]

Wifi is unstable, performance is typically not fast enough for video streaming except low quality youtube stuff. Troubleshooting wifi is something you'll have to fix on your own. Not to mention the 300Mb/sec is theoretical. Typical speeds are 1/10th that if you are lucky and are in the same room.

 

[paleoN]

what should i be looking at?

Typically, troubleshoot with a wired connection first. If that works than it's a wireless problem.