Network Performance Questions

[kjparenteau]

I have FreeNAS 8.0.4 working for the most part, and still working on tweaking a bit. Everything seems to be working the way it should with the exception of network performance and I am unsure if this is normal behavior or not and cannot find much in terms of what is actually wrong. Granted this may not be the biggest deal in the world, but I would think that I could get better performance out of this thing.

I have a noticeably faster write speed to the NAS, however reading/copying the same exact files from the NAS to my local drive is slower. Also, the write speed being fast is great, but it jumps very high and drops down very low and is inconsistent almost the entire time. The copy back to my local HDD seems to be much more steady and consistent, just at a slower pace. To my understanding and experience with other NAS's such as Buffalo Linkstation etc., I would expect the write speed to be slightly slower, and the read speed to be much faster, and either way the network performance to maintain some level of consistency.

Also for reference, here's my setup for hardware / setup in case that might explain things. I know it's not premium stuff or server grade so I'm not expecting crazy things, but I would think it's decent enough to get some more consistent numbers where the read/write performance is concerned. :) Here's some specs and screenshots of the numbers I am seeing while copying a couple of very large files to and from FreeNAS.

FreeNAS-8.0.4-RELEASE-p3-x64
Optiplex 745
PendiumD Dual Core 3.0ghz
8GB DDR2 (4x2GB)

1x 2TB
1x 1TB
4x 500GB

ZFS - Striped and it is seeing a total of 4.5TB


[size=+1]Copy from local HDD to FreeNAS[/size]

[size=+1]Copy from FreeNAS to local HDD[/size]

 

[kjparenteau]

I may have found something, but some input would be great. I read that ZFS does something with the cache which might be causing some of those inconsistencies, but not sure. Also still haven't found an explanation as to why the write speed is actually faster than the read speed. That definitely doesn't make sense to me...

 

[Mati2580]

I thought only I have this problem, please let me know if you find some solution for this case.

dd test says I can write on freenas zfs about 90 MB/s.

http://img10.imageshack.us/img10/9497/cifswindows2freenasspee.jpg

regards
Mati

 

[kjparenteau]

Still have not found a solution to this issue... I would really like to see the performance smoothed out soon, but not sure where else to look. I'm definitely a noob when it comes CLI outside of the Windows environment, but if someone can point me in the right direction towards a solution, I'm sure I can pick up some CLI knowledge in this pretty quick. Thank you in advance for your patience and support.

 

[cyberjock]

I may be wrong, but with 6 drives I'd expect MUCH more than 90MB/sec. I'd expect at a minimum 200MB/sec. You have a bottleneck somewhere. Are your hard drives hooked up to a PCI card? It could also be your different sized drives or your CPU. 8GB of RAM should be good "enough". Although the recommendation is 1GB per TB of hard disk space.

Being that your network load fluctuates during wrotes to the FreeNAS server, that's indicative of your server not able to keep up with those rates. There's some tweaking you could do, but I wouldn't expect tweaks to help you at all if you have a zpool that only performs at 90MB/sec. Any tweaks would like give you a slower average performance without the pauses in writes. Your reads will likely be unchanged(or hardly changed). Most people have trouble getting high NIC utilization and not with hard drive writes. My 8 drive zpool RAIDZ2 does almost 400MB/sec. My NIC is by far the most limiting point for networking.

 

[paleoN]

Granted this may not be the biggest deal in the world, but I would think that I could get better performance out of this thing.

Is this a CIFs share? If so I wish I had your performance. What were you expecting, line speed?

To my understanding and experience with other NAS's such as Buffalo Linkstation etc., I would expect the write speed to be slightly slower, and the read speed to be much faster, and either way the network performance to maintain some level of consistency.

How fast is your client disk? What else are you doing at the same time? What's your clients CPU Usuage?

The problem you are experiencing is known as ZFS Breathing. I just so happened to do a [thread=7473]write-up[/thread] on it a few months ago. I wouldn't be surprised if your final number comes out differently to mine.

 

[kjparenteau]

paleoN - Yes this is a CIFS share. Not so much of an expectation as simply trying to understand why there were dips in speed over the network link.

I wasn't doing anything at the same time and client CPU / HDD is way faster than the FreeNAS setup anyway. The same client connecting to a fast Windows 2008 Server share hits 98%ish gigabit usage and stays steady the entire time until the file is done. There are no major dips in the network link at all. What is now FreeNAS, the same hardware used to be running a Windows 2008 Server install and got 90-95% gigabit usage and stayed steady like my faster Server 2008 does just slightly slower. Not sure why FreeNAS is so up and down when sending a file to it via CIFS.

What you pointed out with ZFS Breathing seems to make sense. I will read more on your write-up and see what happens from there.

What is the best way to monitor the actual CPU/RAM/Bandwidth of FreeNAS in realtime vs the hourly graphs on the admin panel?