FreeNAS unequal transfer speed

[Grinchy]

Hello,

with my FreeNAS System I've got the problem, that the Transfer Speed is quite unequal. It changes between ~300MB/s (sometimes even down to ~100MB/s) and 800MB/s while transferring ~1gb Files. It goes up to 800MB/s, 2secs later it is back to 300MB/s and 2sec more it's back to about 800MB/s. First i thought it could be the lack of RAM, but even after upgrading from 16GB to 48GB the transfer Speed remains the same.

I'm using 7x WD80EZAZ in Raid Z2 in combination with (now) 48GB Ram and an ConnectX 2 10Gbit Card.

Tested my ConnectX 2 with iperf and it worked flawless at about 9.5Gbit/s for 180sec.

Is there a way to fix this?

Thank you!

 

[wblock]

If iperf shows no problem, the problem is the client. The numbers could indicate that the client gets an initial burst copying data to buffers (RAM), then has to flush that data to disk.

 

[Ericloewe]

I'll point out that your pool is barely able to saturate a 10GbE link under optimum conditions. The behavior you're seeing doesn't seem too far from what I'd expect from your pool.