Network speed drops after few seconds from 465MB/s to 100MB/s on 10Gb/s LAN

[Nik]

Hi all,

I just upgraded my NAS with 10GbE cards and have decent speed on small files but with big files (like 40GB) the speed drops after a few seconds from 465MB/s to around 100MB/s.
What can be the reason for this behaviour?

Freenas (see details in the signature) - Chelsio S320E-LP with a Finisar and a Cisco SFP+

Two Clients:
1. Windows 8.1 with a Intel 10GbE XR SR with Finisar SFP+ using CIFS
2. Macbook Pro 2011 with Maverick, Sonnet Thunderbold extension Chassis with Solarflare SFN5122F 10GbE with a Finisar SFP+ using AFP

Both clients show the same problem.

With dd on my Mac I don't over 250MB/s writing and 210MB/s reading speeds.

Code:

dd if=/dev/zero of=/Volumes/cloud/testfile bs=2048k count=2k
2048+0 records in
2048+0 records out
4294967296 bytes transferred in 16.910207 secs (253986681 bytes/sec)
 
dd if=/Volumes/cloud/testfile of=/dev/zero bs=2048k count=2k
2048+0 records in
2048+0 records out
4294967296 bytes transferred in 20.494372 secs (209568135 bytes/sec)

Any idea what can be the problem?

- Nik

 

[cyberjock]

Sorry but we don't provide support for FreeNAS in a VM. There are complexities involved that you may or may not be aware of, and as we have already been around and around with data being lost we do not answer questions related to FreeNAS in a VM. We do not want to give the impression that it is a good idea or we endorse it.

Sorry.