Transmission chokes up the whole system

[iks]

I am running Transmission 2.77 (14031) in Jail and when it is downloading something near full speed (100MB/s), the whole FreeNAS box becomes unresponsive. It struggles to show me CIFS folders and when I click something either windows Explorer stops responding or media files fail to start playing... Even WEB interface is somehow slow...

I have 1GB network:
em0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu 1500
options=98<VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
ether 00:0c:...
inet 192.... netmask 0xffffff00 broadcast 192.168.0.255
media: Ethernet autoselect (1000baseT <full-duplex>)
status: active

And transmission settings reasonably relaxed.
TOP on FreeNAS box shows that transmission-daemon is using 10-15% of CPU time.

So, CPU is not fully used, I have more than enough network bandwidth still available, disk read/write is not pushed to the max - then what is causing this extreme lag?
And I am coming from custom debian box that had the same settings and everything was working fine... So I winder what is happening here...

My specs:

Hostname ...
Build FreeNAS-8.3.1-RELEASE-x64 (r13452)
Platform Intel(R) Core(TM) i3 CPU 540 @ 3.07GHz
Memory 2032MB
System Time Thu May 02 13:38:59 CEST 2013
Uptime 1:38PM up 11:38, 1 user
Load Average 0.00, 0.03, 0.04
Connected through ...

 

[cyberjock]

Well, 100MB/sec is a damn good speed. You're probably seeing 2 things. One, if you are using ZFS, you can expect poor performance.. you don't have then 6GB minimum recommended RAM. Two, with 100MB/sec going to your hard drive in random writes you can expect the system to be darn near unresponsive. That's alot of data to be writing, especially for random writes!

 

[iks]

Hi cyberjock,

Thanks for your answer. Yes I am using ZFS, so it must be it. And I also forgot to mention that this is my home server and when that that problem occurs, all the reads/writes are happening on poor WD Green HDD. I'll change it for two reds in raid in the future, but now it is like this... Well I'll assign some more RAM to the machine as it is VM and I'll report back with the results...